Before you look any further, make sure that you are running the latest version of PTGui. The current version is 8.0.2. See the version history for possible bugs that have been fixed in recent versions. If you are a registered user, you can upgrade at a reduced price, or free of charge, depending on the date of your original order.

Tutorials

The Quick Tour on this site should help you get started using PTGui. The Links page contains links to more tutorials, written by users of PTGui. Tutorials for advanced usage of PTGui and PTGui Pro can be found on the Tutorials page.

Getting support

If you have a question or problem please first check the list of frequently asked questions below. The answer to your question may already be listed there.

If this does not solve the problem you can get support as follows:

Technical support forums

Please post your technical support questions to the PTGui Group. This is the place to talk about PTGui with several hundreds of other users and get technical support directly from the PTGui authors. This forum is hosted at Google; you need to login with your Google Account, or follow the instructions to create a new account.

The PanoToolsNG Group is an active community dedicated to panoramic imaging, not specific to PTGui. This is a good place to discuss technique and equipment for panoramic photography.

Contact us

If you are unable to solve a technical problem, or for non-technical questions (e.g. related to purchasing, registration keys, downloading) please contact us directly at .

Frequently asked questions

1.1. I lost my registration code
1.2. I tried to enter my registration code, but it doesn't work
1.3. I purchased PTGui or PTGui Pro and I still haven't heard from you after a day!
1.4. I have purchased a PTGui license a couple of years ago. How can I upgrade to the latest version?
1.5. I am a licensed user of PTGui; can I upgrade to PTGui Pro?
1.6. What's the difference between PTGui and PTGui Pro?

2.1. Does PTGui require Adobe Photoshop?
2.2. Does PTGui require Panorama Tools?
2.3. Est-ce-que il y a un manuel français pour PTGui?
2.4. Gibt's ein deutsches Handbuch für PTGui?
2.5. My lens database is empty, is that normal?
2.6. Can PTGui work with 16-bit images from start to finish (ie, no 8-bit conversion)?
2.7. Can PTGui create virtual tours?
2.8. When I change the image orientation (landscape vs. portrait) or the focal length multiplier, the focal length value changes. Why?
2.9. Sensor sizes: millimeters vs inches?
2.10. When I crop an image (using the Crop Tab in PTGui), the image appears to be enlarged in the Panorama Editor. Why?
2.11. My images were taken with a (e.g.) 28mm lens, but after optimization, PTGui reports it as a 31.5mm lens
2.12. Can I mix images in portrait and landscape orientation in one panorama?
2.13. Can PTGui read RAW/DNG files?
2.14. What does 'Apply Template' do?
2.15. Does PTGui support multiple processors?
2.16. What kind of computer hardware do you recommend for use with PTGui?
2.17. A PTGui tutorial instructs me to enable the 'Show Script' checkbox, but I cannot find it.
2.18. In the Task manager I see that PTGui only uses xx MB of memory. How can I optimize it to use all available memory?
2.19. Does PTGui preserve the EXIF data of my images?
2.20. Can I stitch images from a shift lens with PTGui?
2.21. Does PTGui run on Windows Vista?
2.22. Where does PTGui store its settings?
2.23. PTGui doesn't fully use my computer's processor(s); the CPU load is less than 100% during stitching
2.24. After optimizing, PTGui shows me the average control point distance. What distance should I aim for?
2.25. I have tried the Panorama Tools optimizer and it gives me lower control point distances. Why?
2.26. Is there a 64 bit version of PTGui?
2.27. Where has the 'low priority' button gone in PTGui 8?

3.1. Error: 'SetMakeParams: Unsupported input image projection'
3.2. Error 'ShellExecute failed' when doing a preview

4.1. After aligning the images, the preview in the Panorama Editor looks completely garbled
4.2. I am trying to edit the seams of a layered panorama in Photoshop, but I only see the bottom layer with the merged panorama; the other layers are transparent.
4.3. I'm having trouble stitching images taken with the Sigma 10-20mm lens in PTGui
4.4. When I create a panorama, the result is blurry or out of focus!
4.5. After optimization, the 'distance' column in the Control Points table is empty for one or more control points
4.6. PTGui fails to install or run on OS X 10.3.9
4.7. Another application crashes when opening TIFF files generated by PTGui, or it displays garbled images.
4.8. PTGui continuously locks up for a few seconds and then becomes responsive again.
4.9. Drag and drop doesn't work with PTGui on Windows Vista

5.1. The horizon of my panorama is curved instead of straight
5.2. I get color/brightness differences between the images in my panorama
5.3. How can I change the resolution (ppi or dpi value) of the generated panorama?
5.4. I see misalignments in the stitched panorama. What can I do to improve the result?

6.1. How do I get straight lines to be straight in the panorama?
6.2. How to create cubic QTVR (Quicktime VR) panoramas
6.3. How do I use the Horizontal line and Vertical line control points?
6.4. How can I calibrate my lens parameters?
6.5. Does PTgui allow stitching of photos that have the camera in different locations?
6.6. How can I stitch mosaics, like partial scans from a flatbad scanner of a large image?
6.7. My panorama was taken with the camera tilted up or down. Now there's a lot of unnecessary black space above/below the panorama, increasing the size of the output. Can it be cropped away before stitching?
6.8. How can I have better control of the overlap area (i.e. the location of the seams)?
6.9. How can I create a vertical panorama? PTGui rotates my panorama 90 degrees!
6.10. I want to cover the tripod in my (360x180 degree) spherical panorama. How do I add a nadir cap?
6.11. How can I change the default settings for new panoramas?
6.12. How can I stitch extremely large panoramas?
6.13. How can I align a set of images, all taken in the same direction (not a panorama)?
6.14. How can I use exactly the same stitching settings for different sets of images?
6.15. How can I stitch images taken with different lenses or different zoom settings in one project?
6.16. How can I correct a single image for lens distortion?
6.17. How can I show a 360 degree panorama on my website?
6.18. How can I show a high resolution panorama on my website?
6.19. How do I level/straighten a panorama using horizontal / vertical line control points?
6.20. How can I correct a single image for vignetting in PTGui Pro?
6.21. How can I retouch the nadir or zenith of a stitched panorama?
6.22. I would like to create a QTVR in PTGui, but it needs some retouching in (e.g.) Photoshop. How can I do this?

7.1. Command line parameters for Autopano don't work!
7.2. Autopano does not find any control points!

8.1. 'Please tell me where the PTStitcher application is! Select Options in the Tools menu of PTGUI'; 'You have configured a PTStitcher application different from PTStitcher.exe' (Windows only)
8.2. No output is generated when creating the panorama using Panorama Tools (PTStitcher), though the Panorama Editor window works fine
8.3. What does the Morph-to-fit feature do?

9.1. What is the best way to take images for HDR stitching in PTGui Pro?
9.2. My images don't contain EXIF exposure information. Can I still use them to stitch HDR panoramas?
9.3. PTGui Pro doesn't recognized my bracketed exposures!
9.4. The stitched HDR panorama looks like it was not blended at all. I'm seeing hard edges between overlapping images.
9.5. So I forgot to switch my camera to M mode; my bracketed images are taken in auto exposure mode. Can I still stitch them to HDR in PTGui Pro?
9.6. Why should I use manual exposure mode? Isn't it much better to use automatic exposure, so that every image is optimally exposed?
9.7. PTGui Pro displays the wrong EV values! My images were taken at -2, 0, +2. This is confirmed by the EXIF data but PTGui shows something else in the Image Parameters tab.
9.8. What's the deal with linked images?
9.9. Should I link my bracketed exposures or not?
9.10. Can I retouch an HDR panorama, e.g. to remove ghost images of moving people?
9.11. I would like to stitch my panorama in PTGui Pro, but use another application (e.g. Photomatix or Photoshop) to create the HDR.
9.12. I've chosen a 16 bit file format for my HDR output and the generated output is very dark. Why?

No problem; we can resend your registration key to you. The registration key is quite long and it is easy to make mistakes when trying to manually type it. Instead it's much easier to copy the registration code from your order confirmation e-mail by selecting the code and pressing CTRL+C, and paste it into PTGui using CTRL+V (Mac users use Command+C and Command+V instead).

The registration key and registration name are linked to each other. Be sure to enter the same registration name that is listed in your order confirmation email.

If you don't have the registration key anymore, we can resend it to you. We send you your registration key as soon as possible after receipt of your payment, though this may take up to 24 hours. If you still haven't heard from us after that time this means that our email has not reached you, likely because it was misqualified as spam or junk mail by your mail program or by your ISP.

If your mailbox has a Junk Mail folder, look for mail from PTGui Support <support@ptgui.com>. Many junk mail filters have a white list feature (often called 'trusted senders'). After adding our address to the white list, go to this page to have the registration key and invoice sent to you again. You should receive a mail from us within a few minutes.

If you still do not receive anything, please send us an email, but be sure to use a different email account otherwise our reply may not reach you either. Every PTGui and PTGui Pro license comes with one year of free upgrades. After that year you can purchase an upgrade license at a discounted price, which includes another year of free upgrades. See Order upgrade for more information. Yes, you can upgrade from PTGui to PTGui Pro at a discounted price. See Order upgrade for more information. See Features of PTGui and PTGui Pro.
No. Although Photoshop users can benefit from the layered Photoshop output of Panorama Tools, it is not required to run PTGui. Since version 5, PTGui does not require Panorama Tools anymore. However, Panorama Tools is still supported; Panorama Tools can be used as a stitching and optimization engine in PTGui.

PTGui handles nearly all functionality of Panorama Tools natively, but Panorama Tools is still required in the following cases:

• 'line' type control points
• 'morph to fit'

The latter two can be considered advanced/experimental use, and are not used in normal stitching projects.

In PTGui, you can choose to use Panorama Tools for stitching in the Advanced section of the Create Panorama tab. The Advanced section is visible only if you click 'Advanced' in the Project Assistant. Panorama Tools can be used from PTGui in two ways:

• 'Stitch using Panorama Tools (PTStitcher)': the complete stitching process is done by the stitcher (PTStitcher) of Panorama Tools. In this mode, certain output formats of PTGui are not supported (such as 16 bit layered Photoshop files). Further, PTStitcher has a limited output size: problems can occur if the width or height is greater than 20000 pixels.
• 'Stitch using PTGui (but warp using Panorama Tools)': PTGui will call Panorama Tools to transform ('warp') the images, but the final output files are assembled by PTGui. PTGui will automatically fall back to this method if it encounters a lens type not supported natively. In this mode, all PTGui-specific output formats are still supported and very large panoramas can be created using the .psb output format.

Similarly, you can choose which optimization engine to use at the bottom of the Optimizer tab (visible only in Advanced mode). The PTGui optimizer can handle all regular panoramas. You still need the Panorama Tools optimizer if your project contains 'line type' control points; also, Panorama Tools may give better results for 'horizontal line' and 'vertical line' control points. On the other hand, the PTGui optimizer may be able to optimize the field of view for non-360 degree panoramas, where the Panorama Tools optimizer may fail. The reported control points distances after optimization for the two optimizers should not be compared, since they are measured in different ways.

Panorama Tools can be downloaded here. The manual for PTGui is in english only, but Adrien Bonnat wrote a tutorial en français / in french There's no German manual, but Bernhard Vogl wrote a tutorial auf deutsch / in german. Yes, it is. You can use it to store your optimized lens data. Yes, PTGui performs all image processing in 16 bit if a 16 bit output format is selected on the Create Panorama tab. To avoid confusion, the term 'virtual tour' commonly refers to a presentation (a website or a CDROM) consisting of multiple interactive panoramas where the user can navigate between panoramas by clicking on hotspots in the panorama, or by clicking on a map or floor plan.

PTGui can create interactive panoramas (just choose QuickTime VR output in the Create Panorama tab), but if you would like to combine multiple such panoramas into a true virtual tour, you need third party software. See Q6.17 for recommendations.

Most of the panorama viewers mentioned in Q6.17 can create virtual tours by linking the panoramas using hotspots. In Pano2VR and Flashificator authoring is done in a graphical user interface, while for the other viewers knowledge of XML and/or JavaScript is required. Internally in Panorama Tools and PTGui, lenses are characterized by their horizontal field of view, not by the focal length. If you replace a portrait image by a landscape image, still the same horizontal field of view is used, but because the aspect ratio has changed, the same field of view corresponds to a different focal length. In that case simply re-enter the right focal length. The same applies when you change the value of the multiplier. In the EXIF window, PTGui will show you the size of the optical sensor in millimeters (if the data or your camera is available). Most manufactures however will state the sensor size in fractions of an inch (e.g. 1/2.5"). The inch-designation dates back to TV camera tubes in the 50s and it does not appear to be mathematically related to the actual sensor size. For more information, read Sensor Sizes at DPReview.com When the Crop Tab is used to crop an image, the field of view value (on the Lens Parameters tab) is the field of view of the cropped portion of the image (and not the field of view of the original image). Since cropping does not alter the field of view of the visible part of the image, the cropped portion of the image will take the same space in the panorama as would the uncropped image. So cropping effectively zooms into part of the image.

The Crop Tab is intended to be used for lenses that use only part of the film/ccd plane, or for scanned images, where the scanned area is larger than the actual image. Generally, all images in a project should have the same crop size, unless individual lens parameters are used for the cropped image(s).

If your goal is to exclude certain unwanted parts of a source image from the panorama, don't use the Crop Tab. Instead, stitch the panorama to a layered format, and use an image editing program such as Photoshop to hide the unwanted parts, after stitching. Or, alternatively, remove the unwanted parts from the image prior to stitching, by making the area in the source image transparent. This requires source images in TIFF or PNG format, which support transparency. The optimizer adjusts your project in such a way that the lowest control point distance is obtained. This may include modifying the field of view / focal length of the lens (if selected for optimization). There can be several reasons for the difference:

• If you have cropped your images in PTGui, the field of view applies to the cropped part of the image
• The value reported in the EXIF data is not very accurate. For example, certain zoom lenses encode the focal length in only 16 steps.
• The lens correction parameters (a/b/c) influence the field of view, so the difference in fov may partially compensated by the lens correction parameters.

Since the optimized value corresponds to the lowest control point distance, the value determined by the optimizer will generally result in the best alignment of the images. This is not recommended, since the Project Assistant of PTGui expects all images to have the same aspect ratio (and hence the same orientation). This is due to the fact that lenses are characterized in Panorama Tools (and PTGui) by the horizontal field of view, and the Project Assistant attempts to optimize the horizontal field of view of all source images to a single value.

Therefore, if you want to mix portrait and landscape images, you currently need to rotate all landscape images or all portrait images in a graphics editing program, prior to loading in PTGui, so that all images in the project have the same orientation. The Project Assistant will be able to determine the original rotation of the images and rotate those images back to their original orientation in the panorama.

[actually it is possible to stitch mixed portrait and landscape images in PTGui without rotating images first, by using 'individual lens parameters'. However, this is considered advanced use, and is not supported by the Project Assistant] No, currently this is not supported.

If you need the image quality of RAW files, you can do a batch conversion of your files into 16 bit TIFF files and stitch these with PTGui. A 16 bit TIFF file has more dynamic range than raw files, which typically contain only 12 or 14 bits per pixel, so the image quality is preserved. This copies the settings of another project to the current project, except for the images and the control points. This function is accessible both from the 'Apply Template' item in the File menu, and from the toolbar in PTGui. A template can be any PTGui project. In Tools/Options/Folders&Files, a folder can be configured where you store your templates (on Mac go to the PTGui menu, Preferences, Folders&Files). Then, the template selection dialog will by default open in this folder. There's a little triangle button next to the 'Apply Template' button on the toolbar, which shows a drop down list of all templates in the configured template directory, for quick access.

Templates can be useful for a quick initialization of a project (lens settings, rough alignment of images), although this is usually not necessary anymore, now that the Project Assistant in PTGui 5.0 and later automatically initializes the project.

Another use for templates is when you have an exact reproducable setup (high quality panoramic head with fixed angles). In this case you could copy all settings of a previous project and there would be no need for placing control points and optimizing. Yes, as of version 7.3 PTGui supports computers with multiple processors (also called multi-core systems). During stitching and control point generation work is split into multiple parallel running tasks. On multi-core systems, each of these tasks is run simultaneously on a separate processor, thus increasing speed. But keep in mind that the processor is not the only speed limiting factor. Stitching requires a lot of disk I/O and memory access. Therefore, doubling the number of processors will not actually double the speed. PTGui will run fine on an old computer with 256 MB of RAM, and it is even possible to stitch very large panoramas on such a system. The only things you really need for large panoramas is patience, and lots of free hard disk space for temporary storage. You can see how much temporary disk space is required for a project by choosing 'Calculate required temporary disk space' in the Project menu of PTGui. For large panoramas, this can be several gigabytes.

PTGui will at first attempt to use physical RAM memory for temporary storage. Once all available RAM is exhausted, temporary data will be written to disk. Since hard disk access is much slower than RAM access, stitching speed will benefit from the availability of enough RAM. Due to operating system limitations, the regular 32 bit Windows versions and all Mac versions can only access 2 Gigabytes of RAM. Only the 64 bit Windows version of PTGui Pro is currently able to access more than 2 GB of RAM.

For the best performance we therefore recommend a 64 bit Windows system with as much as possible RAM and the 64 bit version of PTGui Pro. If you intend to stitch very large panoramas (requiring more temporary storage than available RAM), use a fast hard disk (10,000 rpm disks or RAID arrays) for temporary storage. Internal SATA harddisks are usually much faster than external disks. Configure the temporary disk to use in Options/Preferences (in the Folders & Files tab).

Finnally a faster processor will of course result in faster stitching. PTGui is designed for multi core processors: a stitching job is split into multiple tasks running concurrently on multiple processors. But often the processor is not the bottleneck; if you have the choice, get extra RAM instead of a faster processor.

There are no video card requirements; PTGui does not use graphics acceleration. Before version 5.0, PTGui relied on Panorama Tools for stitching and optimization. Panorama Tools is controlled by script files and it is possible to make small modifications to the script files before sending them to the stitcher or to the optimizer. Since version 5.0, PTGui includes its own stitcher and optimizer, which don't use script files anymore. However, the Panorama Tools stitcher and optimizer can still be used. To do so, select 'Optimize using: Panorama Tools' on the Optimizer tab, or 'Stitch using: Panorama Tools (PTStitcher)' on the Create Panorama tab (to change these settings, PTGui should be switched to 'Advanced' mode). In both cases a 'Show script' checkbox will become visible. Actually PTGui will use all available memory to speed up the stitching, through the filesystem caching mechanism of the operating system, but this does not show in the Task manager. However, once the panorama exceeds a certain size, it does no longer fit in RAM and stitching must be done directly to disk. For such large panoramas, the disk speed becomes the limiting factor, and using more RAM would not speed up the stitching. Currently, the following metadata is copied to the generated panorama:

• Original date and shooting date of the first image in the panorama
• Camera make and model (only if identical for all source images)
• Exposure data: exposure time, aperture and ISO sensitivity (only if identical for all source images)
• ICC Color Profile (only if identical for all images)

For rectilinear panos, PTGui also adds the FocalLength and FocalLengthIn35mm tag.

For HDR panoramas in PTGui Pro, the 'blend planes' output contains the exposure/iso/aperture of that particular exposure, for merging in external software.

Other EXIF data is currently not copied to the output file. Metadata is only written to JPEG and TIFF images, not to Photoshop files. First of all, you don't need a shift lens if you have PTGui! Shift lenses are often used for architectural photographs: photographing a building from ground level, while tilting the camera upwards, normally results in converging vertical lines. Shift lenses compensate for this effect by shifting the optical axis of the lens relative to the center of the image plane. The result is a photograph where parallel lines remain parallel.

The same effect can be achieved in PTGui: open the Panorama Editor window, press Ctrl-P to switch to 'Panorama Edit' mode. Now drag the panorama upwards or downwards until parallel lines in the scene are parallel in the panorama. You may need to increase the vertical field of view (using the slider to the right of the panorama).

If you do want to stitch images taken with a shift lens in PTGui, change the following parameters:

• Switch to Advanced mode by pressing the Advanced button in the Project Assistant
• In the Lens Settings tab, select 'Individual Shift Parameters' for all images for which the lens was shifted
• Run the optimizer by pressing F5

Regardless whether a shift lens is used, or the panorama was shifted in the Panorama Editor, you will end up with some black space below or above the panorama. Currently this cannot be prevented; you can crop the black space from the final panorama after stitching in a graphics editing program. Yes, the latest version of PTGui runs fine on Vista, there are no known issues. Windows: Most settings are stored in the registry, in
\HKEY_CURRENT_USER\Software\NewHouse\PTGui.
Additionally, the lens database and the default project settings are stored in
C:\Documents and Settings\[your user name]\Application Data\PTGui or in
C:\Documents and Settings\[your user name]\Application Data\PTGui Pro for the Pro version.

Mac: Most settings are stored in
/Home/[your user name]/Library/Preferences/PTGui Preferences.
The lens database and the default project settings are stored in
/Home/[your user name]/Library/Application Support/PTGui or in
/Home/[your user name]/Library/Application Support/PTGui Pro for the Pro version. Stitching and blending requires a lot of disk and memory access. In particular for large panoramas, or on multicore computers, not the processor but the hard disk is the speed limiting factor. The stitching speed can be increased by installing a faster hard disk or a RAID array of multiple hard disks. The control point distance indicates how well a control point pair aligns in the panorama. When the distance is zero, the two points of a control point pair overlap exactly.

One should aim for the lowest control point distance possible, but the actual lowest distance that can be achieved depends on many factors. In general if your images were shot properly using a tripod with calibrated panorama head, a control point distance well below 5 should be achievable. Most remaining misalignments can usually be masked by the blender. An average distance higher than 5 usually indicates a problem, see Q5.4 for solutions.

It's particularly important to look at 'outliers': if a control point has a distance of 20 while the average is below 5, this control point might have been placed on a moving object, or on a similar feature close to the proper location. Use the 'Delete worst control points' function (in the Control Points menu) to remove such outlying control points. Both optimizers work in much the same way and they adjust the same set of parameters. However, different optimization criteria are used. The Panorama Tools optimizer minimizes the distance of the control point pair in the panorama: the two points of a control point pair are projected into the panorama and the distance is measured. The PTGui optimizer minimizes the distance of the control point pair in the source image space: the first point of a control point pair is projected into the second image and the distance (in source image pixels) is measured.

Due to the different criteria, the numerical results are different, but the actual quality of optimization is nearly identical in most cases.

By optimizing the distance in the source images (instead of in the panorama), the PTGui optizer is better able to do a stable optimizion of the field of view in partial panoramas. Additionally, the PTGui optimizer can optimize very large panoramas (say 100 source images or more) much more efficiently than the Panorama Tools optimizer and it supports viewpoint optimization (Pro version only). PTGui Pro for Windows is available as a native 64 bit application. The non-Pro version is 32 bits only, but runs fine on 64 bit Windows. A 64 bit Mac version is not available currently due to the fact that Apple has not ported all OS X libraries to 64 bit.

PTGui has been optimized to create very large panoramas even on systems with little memory, therefore a 64 bit version is not required to create large panoramas. But it does run somewhat faster. Previous versions of PTGui contained a 'low priority' button in the Batch Stitcher. Pressing this button reduced the batch stitcher's process priority so that the batch stitcher would not slow down the computer too much while running in the background. Due to several changes since PTGui 7.3, often CPU usage is no longer the limiting factor. As a result, reducing the process priority would have no effect, since the computer may still slow down due to heavy disk and memory access. Thus a true low priority mode should limit the batch stitcher's disk and memory access as well. Therefore we have decided to remove the low priority setting entirely for now; we may come with a better solution in a future version.
This error is generated by Panorama Tools (pano12.dll), not PTGui. As it says, your lens type is not supported by your version of Panorama Tools. If no preview application has been configured (in Options/Preferences, in the Folders&Files tab), PTGui will ask Windows to open the generated panorama using the default application for viewing JPEG files. Normally, Windows is configured to use the built in image viewer application to open JPEG files, but an installed application can modify this setting so that it becomes the default application for opening JPEG files. A misbehaving application, or an application that was not uninstalled properly, can cause Windows to fail opening JPEG files, resulting in the above error.

To solve the problem:

• Start Windows Explorer and browse to any folder on your PC containing JPEG images
• Right-click on an JPEG file and choose 'Open With...'. In Windows Vista, additionally click on 'Choose Default Program...'.
• Select the default program you want to use to view JPEG images, and enable 'Always use the selected program to open this kind of file.

Now Windows should be able to open the preview file generated by PTGui.

Alternatively, you can configure a specific preview application in PTGui: Go to Tools/Options (or PTGui/Preferences on Mac). In the Folders&Files tab, configure the application you want to use for previewing. Different preview applications can be configured for each panorama projection. PTGui will launch the thus configured application for previewing instead of relying on Windows to open the JPEG file using the configured default viewer.
If this happens, it is usually caused by the control point generator adding control points between unrelated images. This can happen in particular with panoramas taken in a completely symmetrical room. Although PTGui can handle images with repeating or identical structures, if your images contain large areas with identical contents on different sides of the panorama, the control point generator may get confused, and add control points between unrelated images, for example between opposite walls.

The solution is to manually review the control points. This can be a tedious process, especially if the panorama consists of many images. Go to the Control Points tab. Select the first image (image 0) in the left pane. The numbered tabs in the right pane will be shown in a bold font if there are control points between the image selected in the left pane and the image in the right pane. In the right pane, go through all the tabs with bold numbers, and check whether the two images really overlap. If the images are unrelated, delete all control points for those two images. This can easily be done by selecting all control points in the table at the bottom of the Control Points tab, and pressing the Delete key. Repeat this process by selecting the second image in the left pane, and so on.

Reset the lens parameters to their default values. This can be done by unchecking the 'Automatic' checkbox in the Project Assistant, and checking it again. The lens parameters are now reset to the values found in the EXIF data.

Finally press F5 to run the optimizer. If you have deleted all faulty control points, the optimization result should be 'good' or 'not bad'. This is by design, please see the post processing tutorial.

The long answer:

This question is sometimes asked by users upgrading from PTGui 4 to PTGui 5. PTGui 4 and earlier versions relied completely on Panorama Tools for stitching. Panorama Tools has two layered output formats: 'Photoshop without feather' and 'Photoshop with feather'. Both formats generate a multi layered Photoshop file, where the contents of each layer are revealed by the layer mask. In Photoshop, this can be seen in the layers palette: the layer mask thumbnail contains white (opaque) inside the warped image, and black (transparent) outside. You could change the location of the seam by painting the layer mask with a black or white brush.

Since version 5, PTGui has its own stitching and blending engine. One of the new features is the 'blended+layers' output format. In this format, the bottommost layer contains the blended image, and above that are the individual warped source images. The blended image is created using a multi band blending process. Multi band blending is more intelligent than the alpha mask blending that is used by Panorama Tools, in the sense that it distinguishes between slow changing contents in the image (like a gradual change of blue in the sky) and fast changing contents (like leaves in a tree). Slow changing contents are merged over a broad transition area, while fast changing contents are merged with a relatively sharp seam. The result is a much better blend than what can be achieved using simple alpha blending. The drawback however is that editing the seams is more difficult, since the blending process cannot be represented by a simple alpha mask that can be edited.

In order to allow editing the seams, while still benefiting from the quality of multi band blending, a new layer configuration is used. The bottom layer contains the blended image, and the layers above contain the individual warped source images. The layer masks of the individual warped images are transparent by default, so the layers are invisible. You can paint with a white brush in the layer mask to make parts of the layer visible, and thus overlay the contents of that source image over the blended result. The process is explained in the post processing tutorial. The best results are obtained when the 'color correct source images' checkbox is enabled: this reduces any color differences between the source images, so that the seam becomes less noticable.

If you still prefer to use the original Panorama Tools layer configuration, you have two choices: you can choose 'Stitch using: Panorama Tools (PTStitcher)' in the Advanced section of the Create Panorama tab (this setting is only visible if you press Advanced in the Project Assistant). Or you can choose 'Layers: Individual layers only', which gives a result similar to the 'Photoshop without feather' format of Panorama Tools. When starting a new project, PTGui initializes the lens parameters based on the EXIF data that is embedded in images from most current digital cameras. The EXIF data contains information about the focal length of the lens and the size of the sensor in the camera. Besides this data, PTGui also needs to know the projection of your lens. Most SLR lenses and all consumer cameras have rectilinear ('flat') projection, but some wide angle lenses have a fisheye projection.

Unfortunately, the EXIF data does not tell which projection the lens has. PTGui guesses the projection based on the focal length of the lens: SLR lenses with a focal length below 15mm are assumed to be fisheye lenses; higher focal lengths are assumed to have rectilinear projection. This is a good assumption in general, but the Sigma 10-22mm lens is one of the few exceptions that generates a rectilinear image with a focal length below 15mm.

To stitch these images in PTGui, be sure to select the right lens type before running the control point generator, otherwise it will fail to find control points. In the Project Assistant, after loading the images, deselect the 'Automatic (use EXIF data from camera)' checkbox, and switch the Lens Type to Rectilinear. Then proceed to step 2 (Align Images) and continue the rest of the process as normal.

If you don't use fisheye lenses, you can configure PTGui to always assume rectilinear projection for your lens: go to Tools/Options (on Mac go to the PTGui menu, Preferences), EXIF tab and change the 15mm values to 9mm. Actually the result is not blurred; it's just that the generated panorama is very small. PTGui can generate a panorama at any size you desire. To do so, increase the width and/or height values in the Create Panorama tab before generating the stitched panorama. To get a panorama at the highest quality, press the 'Optimum Size' button and choose 'Maximum Size'. The resulting panorama will have approximately the same resolution (level of detail) as the original images.

The same applies to the Preview function: in the Preview tab, increase the width and/or height before generating the preview image. This has one of the following causes:

1. This particular control point was disabled for optimization. Enable it by right-clicking on the control point and enable the 'Optimize' checkbox.
2. All control points of a particular image were disabled for optimization, using the 'use control points of' list in the Optimizer tab.
3. This particular control point was placed between two linked images in a HDR panorama. If two images are linked, they will be overlaid exactly and control points between the two images are ignored by the optimizer.
4. This particular control point is a horizontal / vertical line control point. The PTGui optimizer only reports control point distance for normal control points.

Applications developed with recent versions of Apple's software development kit no longer appear to support OSX 10.3.9. The latest versions compatible with OSX 10.3.9 are PTGui and PTGui Pro 7.3 (download available for licensed users only). We recommend you upgrade your mac to OS X 10.4 (Tiger) or 10.5 (Leopard). TIFF is a container format which can contain many different types of image data; almost no application supports all possible TIFF formats. PTGui can create 16 or 32 bit TIFF files and TIFF files with an alpha channel but these features are not supported by many applications. If you need create a compatible TIFF file, press the 'Settings' button in the Create Panorama tab, and choose: 8 bits, no alpha channel and no compression. The resulting file can be opened in nearly every application that supports TIFF files. This is a known problem with the McAfee version 8 virus scanner; possibly this applies to other virus scanners too. PTGui stores image data in temporary files; these files are accessed continuously, for example when scrolling an image in the Control Points tab. Some virus scanners feature 'on access scanning', where every file is scanned when an application attempts to access it. Scanning large files may take several seconds and the virus scanner suspends the application until scanning has finished. Therefore using on access scanning on PTGui's temporary will cause intermittent lockups.

If you see intermittent lockups in PTGui we therefore recommend to disable on access scanning for PTGui's temp files; please consult the manual of your virus scanner for more information. This problem may occur if you run PTGui as Administrator. Vista's security policy in such a case does not allow drag and drop. If you have just installed PTGui and chose 'Launch PTGui now' at the end of the installation, PTGui will run with administrator privileges (since the installer runs with administrator privileges). Exiting PTGui and launching it again from the Start menu should solve the problem.
See Tutorial: straightening a panorama Always make sure to lock the exposure and white balance of your camera. Color differences can be corrected to a certain amount by the blending process, but you will get the best results by locking the color balance and exposure when shooting the images. This can be done in the Create Panorama tab, Advanced section. Switch PTGui to Advanced mode to make this section visible.

Be aware though that the resolution of an image has nothing to do with image quality, or print quality. The ppi/dpi value of an image file is just a number embedded in the header of the file, suggesting the number of pixels to be printed in one inch. The number of pixels is what really matters: if you need a more detailed output image, increase the width and height of the output image instead (on the Create Panorama tab). Click the 'Set optimum size' button in PTGui and choose 'Maximum size' to achieve the highest quality. Increasing the output size beyond the optimum size is possible but will only increase the file size, not the amount of visible detail, since the latter is limited by the (angular) resolution of the source images.

See also: The Myth of DPI. First of all, make sure that the photographs are taken properly: for panoramas, all images should be taken from exactly the same viewpoint. If the camera was not rotated around the nodal point of the lens between shots, the panorama will suffer from parallax errors: foreground and background objects are shifted in relation to each other. Correcting for parallax errors in stitching software would be physically impossible; the only remedy is to mask the parallax problem by placing the seams appropriately (see our post processing tutorial). Parallax problems often result in high control point distances: if you have several control points with an optimized distance of 20 or more (see below), this is usually indicative of a parallax problem.

If you use a tripod to shoot panoramas, you need a panoramic head: it positions the camera on the tripod such, that it rotates around the nodal point of the lens. When shooting hand held, rotating the camera around the nodal point can be difficult, but it is possible, for example with the help of a 'Philopod'. Of course, if there are no objects near the camera, rotating around the nodal point is less important. But even with objects a few meters away, parallax errors of only a few centimeters will be noticable.

Misplaced control points can be another reason for misalignment. Especially if there are repeating structures in the images, the control point generator may occasionally misplace one or two control points. The same can happen if there are moving objects in the panorama: slowly moving clouds in the sky are notorious in particular. Finding these misplaced control points is easy: open the Control Point table (CTRL-B) and find the control points with the largest distance. This distance indicates the alignment error of the control point in the panorama. By default, the table is sorted in descending distance, so the worst aligned control points are in the top of the list. In general, a distance below 5 is sufficient, while higher values usually indicate a problem. Double click on a control point in the table to edit it, or delete it by pressing Del.

Misalignment in an area of a panorama can occur if there are no control points in that particular area. Go to the Control Points tab and add a few points in problem areas to improve the alignment there.

A common misconception is that using a wide angle lens would cause misalignments, due to the distortion inherent to wide lenses. This is not true however: PTGui can perfectly correct perspective distortion in wide angle lenses. A panorama from a wide angle lens will thus look exactly the same as the same scene taken with a long lens, apart from any differences in quality and resolution.

Another reason for stitching errors can be a misalignment of the center of the lens to the center of the image sensor in the camera: Ideally, the lens axis should be perpendicular to the sensor plane and point towards the center of the sensor, but in most cameras there is a small offset. By default, the warping and lens correction in PTGui is performed relative to the center of the image. This will result in less accurate image transformation when the lens is mounted off center. PTGui can correct for this using the 'shift parameters' (also called d and e), as follows:

• In the Project Assistant, press 'Advanced'
• Go to the Optimizer tab, and choose 'Minimize lens distortion: Heavy + lens shift'. If the optimizer is in advanced mode, enable the Horizontal shift and Vertical shift checkboxes.
• Press the 'Run Optimizer' button (or the F5 key)

This will shift the source images in such a way that the best optimization is achieved. However, we have not enabled the shift optimization in PTGui by default, since it may give unexpected results if the control points are not distributed evenly across an image. For example, if all control points are located in the bottom half of the panorama (which often is the case if the upper part consists of blue sky), the whole panorama may shift as a result. So it is important that the control points are distributed over the entire image for this optimization to work. Also, shift optimization often fails if there are parallax errors. If it doesn't work as expected, press Undo (Ctrl-Z) repeatedly until the project is restored to its original state.
Rectilinear projection is the only panoramic projection that preserves all straight lines. Equirectangular and cylindrical projection will bend straight lines, except for vertical lines and the horizon of the panorama. Press the 'rectilinear projection' button in the Panorama Editor to switch to rectilinear projection.

Beware that the limit of the horizontal field of view for a rectilinear projection is theoretically 180 degrees, and in practise edge distortion will become too apparent already at 120 degrees and wider. If your panorama is too wide, rectilinear projection cannot be used and so it is impossible to preserve straight lines. This is not a limitation of PTGui or Panorama Tools, but a physical limitation: it simply is physically impossible to project a wide scene onto a flat surface without curving at least some straight lines.

See also: Projections Since version 7, PTGui can create Quicktime VR panoramas directly. To create a QTVR movie, choose 'QTVR' as the file format. The panorama projection should be set to equirectangular, 360 x 180 degrees. This can be done by choosing 'Spherical' in the Panorama Editor Menu / Projections. The result is a cubic .mov file, which can be viewed in the QuickTime Player, or embedded in a web page. John Houghton wrote an excellent tutorial about this.
German readers see this page by Bernhard Vogl For panoramic stitching you don't need to know the lens parameters since PTGui calibrates your lens automatically for each panorama. But knowing the lens parameters can be useful if you (for example) would like to correct a single image for barrel distortion. The lens parameters can be calibrated accurately as follows:

1. Take enough images to build a 360 degree, single row panorama. Make sure the images overlap by at least 30%. Make sure that the camera is rotated around the nodal point of the lens, in order to avoid parallax errors.
2. Load the images into PTGui, and execute step 2 (Align Images) of the Project Assistant.
3. Switch to the Control Points tab and review all generated control points. Remove any misplaced control points, and any control points on moving objects (including clouds in the sky!). Also remove any control points on nearby objects, since these will suffer the most from any remaining parallax errors in your setup. Make sure that each pair of overlapping images has at least 4 control points (more is better). Ensure that there are some control points in the corners of the images as well, not just in the center.
4. Optimize the project using the Optimize button in the Project Assistant.
5. Open the Control Point table (Ctrl+B or Cmd+B). The control point distances should be small, generally less than 3. If you find control points with higher distances, correct or remove them by repeating the previous two steps.
6. Switch to Advanced mode by pressing the Advanced button in the Project Assistant.

Now the optimized lens parameters can be found as the a, b and c parameters on the Lens Settings tab. Use the Lens Database button to save the values for later use.

Please note that different orientations (landscape vs. portrait) and different focal lengths (in case of zoom lenses) will result in different correction values, so be sure to save separate entries in the lens database for each zoom setting and for landscape and portrait orientation. Even at the same zoom setting and orientation subsequent calibrations may result in significantly different a/b/c values. This is normal, since completely different a/b/c values may represent very similar lens correction curves. In general this is not possible. PTGui was designed for stitching true panoramas, by taking overlapping photos from a single camera viewpoint. If the camera is moved between shots, parallax errors will occur. Correcting for parallax errors in software is physically impossible so in general it is impossible to stitch such images without visible misalignments.

There is one exception: if the subject to be photographed is flat, like a wall or like aerial photographs (shot from some altitude and without high rise buildings), parallax faults will not be noticable. Such images can be stitched in PTGui if the following conditions are met:

• the subject should be flat, or if the subject is not completely flat, all control points should be placed on a flat surface only. When stitching aerial photographs, remove any control points that are not on the ground surface.
• the camera should be pointed exactly perpendicular to the subject's surface, i.e. for aerial images the camera should be pointed exactly vertically
• in all shots the camera is at exactly the same distance from the surface

Under these circumstances the photos can be stitched using the process for stitching mosaics, see the section directly below.

If the subject to be photographed is not too wide and the camera can be placed at sufficient distance, consider taking your photographs as a true panorama instead, from a single camera viewpoint. Choose a rectilinear panorama projection so that straight lines in the scene will remain straight in the panorama. The result will probably look better than when attempting to stitch images where the camera was moved between shots. PTGui was designed for stitching panoramas, from photographs taken from a single camera viewpoint. When stitching a panorama, images are warped to correct for perspective distortion so that a seamless overlap is achieved. For mosaic-style stitching on the other hand the images should only be shifted and rotated; any perspective warping is undesirable. PTGui can be tricked to do no warping by setting the field of view of the source images to a very small value, which corresponds to a tele lens with a long focal length.

To stitch mosaics, proceed as follows:

• Start a new project and load your source images
• Switch PTGui to Advanced mode using the Advanced... button on the Project Assistant
• Go to the Lens Settings tab and set the Lens type to Rectilinear. Set the Horizontal Field of View to 1 degree.
• In the Control Points menu choose 'Generate Control Points'
• Go to the Optimizer tab. Deselect the 'Optimize lens Field of View' checkbox. At 'Minimize lens distortion', choose 'Heavy'.
• Press the Run Optimizer button (at the bottom)
• Now go to the Panorama Editor window by pressing Ctrl+E (Windows) or Command+E (Mac). First press the Center Panorama button, then press the Fit Panorama button.

Your mosaic is now ready to be stitched at the Create Panorama tab. No, this is not possible. Panorama Tools and PTGui always stitch in such a way that the horizon is in the center of the panorama. If you need a higher field of view above the horizon, then the panorama will include the same field of view below the horizon. Of course the resulting panorama can easily be cropped afterwards in a graphics editing program. To get full control over the location of the seams in the stitched panorama, stitch to a layered output format. Choose Photoshop output format, and select 'Layers: individual and blended'. By editing the blend masks in an image editing program like Photoshop, you can determine which parts of which source images are used in the blended panorama.

See the Post processing tutorial.

Alternatively you can make the unwanted parts of the source images transparent in a graphics editing program before stitching the images in PTGui. The PTGui blender recognizes the transparent areas and will place the seams around them. You need a graphics editing program to add a transparency mask to the image; in Photoshop you can do this as follows:

• Open the image in Photoshop
• Right-click on the 'Background' layer in the Layers palette and choose 'Layer from background'
• In the Layer menu choose 'Layer Mask -> Reveal All'
• In the Layers palette, click on the layer mask thumbnail (the white rectangle)
• Select a black brush in the toolbox and paint on the mask. The painted areas become transparent.
• When done editing, save the image as a TIFF file. Photoshop pops up a TIFF Options dialog; choose the following options:
  • Save image pyramid: No
  • Save Transparency: Yes
  • Layer compression: Discard layers and save a copy

Then go to the Source Images tab in PTGui, select the original image and press the Replace button at the bottom. Replace the image with the TIFF file you just saved. For single row panoramas, PTGui will always attempt to align the images in a horizontal row. This behaviour cannot be changed, but you can easily rotate the panorama: in the Panorama Editor, simply use the right mouse button and drag the panorama to the right orientation. After rotating, you may need to press 'Fit Panorama' in the Panorama Editor to resize the panorama area so that it fits.

Vertical panoramas usually look best in one of the Transverse projections. You can choose a suitable projection in the Projection submenu of the Panorama Editor menu. There are several options. Peter Nyfeler has created a Photoshop action for adding a mirror ball nadir cap.

Or you could use your own logo. The logo needs to be warped into the projection of the panorama, as follows:

• Start a new PTGui project
• Add your logo image to the project
• Switch PTGui to Advanced mode
• Go to Lens Parameters and select 'Rectilinear' and (e.g.) 60 degrees field of view. The value you enter here sets the size of the warped logo.
• Panorama Settings: Equirectangular, 360x180 field of view
• Image Parameters: set the Pitch angle of the image to -90 degrees
• It's not necessary to add control points or to optimize
• Create Panorama tab:
  Width/Height: same as your original spherical panorama
  Output format: .psd or .tif
  Layers: blended panorama only
• Then press 'Create Panorama'

The result is a warped version of your logo. Overlaying the logo has to be done manually in a graphics editing program. A quick way to do this in Photoshop is by selecting the entire logo image (Ctrl-A), copying it (Ctrl-C) and then pasting it into the panoramic image (Ctrl-V). This creates a new layer in the panorama with the logo. Choose 'Make Default' in the file menu to save the current settings as a starting point for new projects. This will save all settings, except for the images and control points.

Even though you changed the defaults, the Project Assistant will still override certain settings (such as the panorama projection) in order to ensure a good result. Your file format settings will not be overridden if you switch to Advanced mode before generating control points. If you really need full control over all settings, don't use the Project Assistant: if you instead choose 'generate control points' in the Control Points menu, PTGui will do only that and leave the other settings as they are. Be sure to select 'Stitch using: PTGui' on the Panorama Settings tab. If you do need to use PTStitcher, use only the 'Multi-image TIFF without feather' format. Other file formats are known to cause the Panorama Tools stitcher to crash on large output files.

The maximum output size in PTGui depends on the file format:

• JPEG: max 25,000 x 25,000 pixels
• TIFF: unlimited dimensions, but the TIFF specifications allow a maximum file size of 4 GB. Certain applications (including Photoshop CS2) fail to read TIFF files larger than 2 GB. Older Photoshop versions cannot read images wider or taller than 30,000 pixels.
• Photoshop .psd: max 30,000 x 30,000 pixels and a maximum file size of 4 GB (Photoshop CS2) or 2 GB (Photoshop CS)
• Photoshop .psb: max 300,000 x 300,000 pixels, no file size limitations

Clearly, the .psb format is the choice for large panoramas, but unfortunately this format is not widely supported (you need Photoshop CS or later).

Predicting the file size of a TIFF or .psd file is difficult, since this depends on the degree of compression that can be achieved. For large panoramas, you may find that the resulting file is larger than the 2 GB or 4 GB maximum and cannot be opened. You can keep TIFF files generated by PTGui as small as possible by choosing 8 bit output, LZW compression and 'no alpha channel' at the file format settings in the Create Panorama tab. This can be done using PTGui; it can be used for (e.g.) accurately aligning a set of images for manual HDR creation, for making a time lapse movie, or for extending depth of field by merging images taken at different focusing distance.

It requires a special workflow though. By default, PTGui expects that a project contains overlapping source images, taken from the same viewpoint, but in different directions. The perspective changes that occur when the camera is rotated allow PTGui to accurately calculate the focal length (or field of view) of the lens. When all images are taken in the same direction, this information is missing and PTGui may end up optimizing the lens parameters to wrong values. This can result in a very small field of view, or introduce barrel distortion.

If the images are taken in one direction, they can be aligned in the following way:

1. Load the source images in PTGui.
2. Switch to Advanced mode by pressing the Advanced button in the Project Assistant.
3. Go to Lens Settings and make sure that the correct focal length for your lens is configured. In most cases PTGui will have been able to determine this automatically, based on the EXIF data of your images.
4. Go to the Optimizer tab, uncheck 'Optimize lens Field of View' and choose 'Minimize lens distortion: No'.
5. In the menu bar, choose Control Points|Generate Control Points.
6. Press F5 to launch the optimizer. The images are now aligned properly.
7. In the Panorama Editor window, press the Fit Panorama button. Optionally adjust the field of view sliders if you want to crop away part of the output.
8. In the Create Panorama tab, choose 'Layers: individual layers only'.

If you select Photoshop output, a single Photoshop file is created, with each aligned source image in a separate layer. With jpeg or tiff output, separate files are generated for each source image. This can be useful for creating HDR panoramas, where the bracketed exposures have been taken in identical orientations, or for stitching panoramas that were taken with an exactly reproducible setup (using a panorama head with accurate click stops).

To stitch multiple panoramas with the same settings, the Apply Template function can be used (also see Q2.14). Create the first panorama in the regular way and save the project file. For the subsequent panoramas do the following:

• Start a new project
• Load the source images
• Switch to Advanced mode by pressing the Advanced button in the Project Assistant
• Choose 'Apply Template' from the File menu and browse to the project file saved earlier
• Go directly to Create Panorama to stitch the result. Don't add any control points and don't press Align Images

By default, PTGui assumes that all images have been taken with the same lens, at the same zoom setting. If multiple lenses or zoom settings have been used, do the following:

• Switch to Advanced mode by pressing the Advanced button in the Project Assistant
• Lens Settings tab: mark the Individual Lens Parameters checkboxes of the images that were taken with the different lens or zoom setting
• Image Parameters tab: Make sure that the correct lens type is chosen for the images. Set the focal length to a suitable initial value.

Please note that the control point generator currently assumes that all images were taken with the same lens, hence it may fail to find control points for all images. In that case, you will need to add a few control points by hand. See the notes in the Control Point Assistant window for guidance. Once the project contains sufficient control points, press F5 to run the Optimizer. To do this, you first need to get the calibrated parameters of your lens, as described in section 6.4. Save the calibrated values to the lens database in PTGui.

To correct a single image:

• Start a new PTGui project
• Load the image to be corrected
• Switch to Advanced mode by pressing the Advanced button in the Project Assistant
• Go to the Lens Settings tab
• Press the Lens database button and load the previously calibrated values
• Open the Panorama Editor (press Ctrl+E on Windows, or Command+E on Mac)
• Choose Rectilinear in the Projection menu in the Panorama Editor
• Choose Fit Panorama in the Edit menu in the Panorama Editor
• Optionally move the sliders to adjust the cropping area
• Go to the Create Panorama tab, press Optimum Size and choose Maximum Size
• Choose 'Layers: Blended panorama only'

After the above steps, the project can be saved as a template. For subsequent images, start a new project, load the image to be corrected, choose File | Apply Template, and pick the template project.

Since lenses are characterized in PTGui by their horizontal field of view, separate calibrations are required for landscape and portrait images. The easiest way to do this is by creating a QuickTime VR movie in PTGui. In the Create Panorama tab, choose 'File Format: QuickTime VR (.mov)'. To show the panorama on your website, download viewqtvr.zip. This zipfile contains the necessary files to include on your website; instructions are provided in readme.txt. To view QTVR panoramas visitors to your website need to have QuickTime installed. QuickTime is a product of Apple which is installed by default on Mac computers. QuickTime for Windows is included with iTunes or it can be downloaded from Apple.

Alternatively, panoramas can be displayed using the Flash plugin. Although the display quality is not as good as QuickTime or Java, Flash has the advantage of being included in nearly every web browser, so your visitors can view panoramas without installing any software. PTGui cannot create Flash output directly, but several third party Flash panorama players exist. All of them can handle output from PTGui:

• Pano2VR
• Flash Panorama Player
  graphical user interface for Flash Panorama Player: Flashificator
• krpano
• PanoSalado

Finally, panoramas can be displayed in Java using PTViewer. Extremely large panoramas (up to several gigapixels) can be shown in a website using Zoomify. A panorama is first cut into small tiles using the Zoomifyer application. This application can be downloaded from the Zoomify website, or you can use the Zoomify export built into recent versions of Adobe Photoshop. The Zoomify player is a Flash plugin, enabling zooming into the panorama at the full resolution. The PTGui Gallery includes several examples. Besides straightening a panorama manually in the Panorama Editor, it's also possible to level a panorama using 'horizontal line' and 'vertical line' control points. Such control points indicate points that should end up on a horizontal or a vertical line in the panorama. PTGui is able to modify the orientation of the panorama in such a way that the horizontal / vertical line control points are aligned on a horizontal or vertical line, respectively, in the panorama.

Vertical line control points can be placed on any vertical feature in the panorama, such as the side of a building. Horizontal line control points should only be placed on the horizon itself: in a spherical panorama, all horizontal lines are curved, except for the horizon itself. For most panoramas (in particular cityscapes) it's easiest to use only vertical line control points. One exception would be a panorama of a sea shore: here you could place horizontal line control points on the horizon.

To add horizontal / vertical line control points, switch PTGui to Advanced mode by pressing the Advanced button in the Project Assistant. While regular control points can only be placed between two different images, horizontal / vertical line control points can be placed within the same image. To do so, choose the same image in the left and the right pane in the Control Points tab. The 'CP type' listbox sets the type of control point that will be created next. Choose 'horizontal line' or 'vertical line'. Then click on two points (one in the left pane and one in the right pane) that should be aligned horizontally or vertically. Even if the two points are within the same image, place one point in the left pane and one point in the right pane.

For most panoramas it's sufficient to place two pairs of horizontal line or vertical line control points. The best results are achieved if the two pairs are at different sides of the panorama.

Now there are two ways to have PTGui align the panorama based on the horizontal / vertical line control points:

1. In the Panorama Editor menu bar, choose Edit | Level Panorama.
   
   PTGui will rotate and move the panorama in such a way that the horizontal / vertical line control points are aligned as much as possible. This is similar to dragging the panorama in the Panorama Editor in 'Panorama Edit' mode: since the panorama is moved as a whole, the alignment of individual images is not affected. Or:
    
2. Use the optimizer by pressing the 'Optimizer' or 'Run optimizer' buttons.
   
   PTGui will first optimize the alignment of the images based on the normal control points. The horizontal / vertical line control points are ignored in this step. In a second pass the optimizer levels the panorama as described above, using only the horizontal / vertical line control points.
   
   If you use the optimizer in Advanced mode (you have pressed the Advanced button in the Optimizer tab), be sure to give the optimizer enough freedom to modify the panorama orientation: The pitch and roll checkboxes for all images should be checked, and the yaw checkboxes for all images except one should be checked.
   
   If you use the optimizer in Simple mode (you will see the 'anchor image' listbox in the Optimizer tab) PTGui will use the correct settings automatically.

If you are used to using the Panorama Tools optimizer, note the different behaviour of the PTGui optimizer. The Panorama Tools optimizer optimizes the project in a single pass, attempting to find a best fit for both the normal and the horizontal / vertical line control points in one go. A drawback of this method is that in order to achieve alignment of the horizontal / vertical line control points, the optimizer may choose to allow slight misalignments between the individual images. With the PTGui optimizer, the alignment of individual images takes priority and is not affected by the horizontal / vertical line control points. Please note the requirement to enable pitch and roll optimization for all images. After using the PTGui optimizer, the 'distance' column in the Control Points table will be empty for the horizontal / vertical line control points, since the optimization criterium for leveling is not related to the alignment of individual images. First you need to determine the vignetting of your lens. To do so, take a small panorama (e.g. 3 images, each overlapping about 50%). The amount of vignetting depends on the aperture of the lens so this should be done for each aperture at which you intend to do vignetting correction. In this calibration project, go to the HDR/Exposure tab and press Optimize Now. Press the Save buttons below the vignetting curve and the camera response curve to save the curves to a file.

The actual vignetting correction can be done as follows:

• Start a new PTGui Project
• Load your source image. Note the lens projection that is chosen by PTGui (e.g. Rectilinear)
• Switch to Advanced mode
• Go to the HDR/Exposure tab and load the previously saved vignetting curve and camera curve.
• Go to the Panorama Editor. Set the panorama projection identical to the lens projection (e.g. Rectilinear or Fisheye).
• Press the Fit Panorama button
• Go to the Create Panorama tab, choose Set Optimum Size -> Maximum Size
• Choose the desired output format and press Create Panorama. PTGui may complain about missing control points; you can ignore this warning.

You can save the thus created project to a file and use it as a template for subsequent corrections: you will only need to start a new project, load the next source image and choose Apply Template.

It's possible to combine this process with barrel distortion correction, see Q6.16. It's often difficult to retouch the nadir and zenith of a panorama, due to the stretching that occurs at the bottom and top of the image. A solution is to reproject the panorama such that the nadir or zenith is in the middle:

• Start a new PTGui project
• Load your stitched panorama (a 360x180 degree equirectangular tiff or jpeg file) as a source image
• Set the Lens Parameters to Equirectangular, horizontal field of view of 360 degrees
• Switch PTGui to Advanced mode
• Go to the Panorama Editor. Switch to Equirectangular projection and press the Fit button
• Open Numerical Transform, enter a Pitch value of -90 and press Apply. The panorama is now reprojected with the nadir in the middle.
• Go to Create Panorama, choose Optimum Size -> Maximum Size and create the panorama

After retouching the nadir in the reprojected panorama, use the same process, but now with a pitch correction of +90 to reproject it back to the original orientation. Instead of creating a QTVR directly in PTGui, create the panorama in equirectangular format first. In the Create Panorama tab, choose 'File Format: Photoshop' and 'Layers: Blended and Layers'. The resuting file can be edited in Photoshop as described in the Post processing tutorial. When you are done editing, choose 'Flatten Image' in the drop down menu in the Layers palette in Photoshop and save the panorama in TIFF or JPEG format. Launch PTGui again and choose Utilities - QTVR converter to convert the panorama to QuickTime VR.
Be sure to use lower case characters and don't add any spaces in the parameters. E.g.: /size:800 Make sure you have the AutoPano plugin version 1.03 or newer. Further, Autopano is known to have problems with certain 16 bit images. As a workaround, replace the images with 8 bit versions while running Autopano.
PTStitcher is the stitcher application of Panorama Tools; if you want to stitch a panorama using Panorama Tools, PTGui needs to know where it can be found. If you installed the PTGui edition of Panorama Tools, this should have been configured automatically.

You can either:

• (re-)install Panorama Tools, or
• Go to Tools/Options/Directories and Files/PTStitcher Application and browse to PStitcher.exe (in the Helpers directory in the directory where you installed Panorama Tools)

This may be due to non-Latin characters in the output filename, such as russian, chinese or hebrew characters. Panorama Tools cannot handle these and may silently fail. To see if this is causing the problem, try to save to c:\panorama.jpg or similar and see if this works. In short: it is a feature of Panorama Tools that ensures that a control point pair will match exactly in the final panorama. Each control point that is selected for morph-to-fit is treated as the corner of a triangle; the triangle mesh is distorted such that the control point pair will match exactly.

In PTGui, morph-to-fit can be enabled on the Panorama Settings tab for all control points or for selected points only. In the latter case, individual points can be selected for morphing in the Control Points tab.

The project should be configured to stitch using Panorama Tools (PTStitcher). Since PTStitcher is not available for Mac OSX, Morph-to-fit can be used on Windows only.

Be aware that morphing will often introduce new unwanted distortion. It's definately not the magic solution to parallax problems, but it may help to correct minor misalignments.
Disable all automatic features of your camera, except for automatic bracketing. In particular:

• Set the camera to the 'M' mode (not the A, T or P mode)
• Lock the white balance
• Disable auto ISO adjustment (if your camera has this feature)
• Enable auto bracketing. Make sure that the camera brackets the exposure time, not the aperture or iso.
• Take a complete bracketed set of images in every direction

The 'M' mode is present on every (digital) SLR camera, but most compact cameras lack this mode, which makes them unsuitable for HDR stitching with PTGui Pro. Yes, just enter the exposure data in the Image Parameters tab. At least the exposure time should be filled in for each image; the aperture and iso fields can be left blank. Switch PTGui Pro to Advanced mode to make the Image Parameters tab visible. Most likely your camera was in automatic exposure mode when taking the images.

Please take a look at the actual exposure data (aperture, exposure time, iso) in the Image Parameters tab. Switch PTGui Pro to Advanced mode to make the Image Parameters tab visible.

For HDR, only the exposure time should be varied. The aperture and iso value of all images should be the same. Further, the exposure times of the images should follow a repeating sequence. For example: 1/25, 1/100, 1/400, 1/25, 1/100, 1/400, and so on.

If the exposure times do not follow such a repeating sequence, even though auto bracketing mode was enabled, this can only be caused by the camera being set to an automatic exposure mode. In automatic exposure mode, the camera adjusts the exposure between each set of bracketed images and as a result, the exposure times will be different in each set of bracketed images.

On SLRs, automatic exposure is enabled in the P, Av and Tv modes. Only in the M mode automatic exposure is disabled, hence the M mode is the only mode suitable for photographing HDR panoramas. Most digital compact cameras are not suitable for HDR panoramas due to the lack of a manual exposure mode. Most likely your camera was in automatic exposure mode; see Q9.3.

In general, the this problem is caused by the fact that the images do not cover the full panorama for every exposure time used. For example, if you took images at (e.g.) 1/25, 1/100 and 1/400s, then a full panorama should be taken at each of these three exposure times.

PTGui Pro groups the images by exposure time, and stitches and blends a complete panorama from each group. These blended panoramas are called 'blend planes'. Finally, the blend planes are merged to HDR and optionally tone mapped.

If an image is missing, e.g. you forgot to take one of the 1/100 images, then the resulting blend plane contains a gap. PTGui will attempt to merge the three blend planes into HDR, but the gap causes a hard edge in the result. HDR merging should not be compared with regular panoramic blending: it does not attempt to create a soft transition between overlapping images. Instead it picks the 'best' pixel data from each blend plane.

To verify that at each exposure time a full panorama is covered, enable the 'blend planes' output setting in the Create Panorama tab. Take a look at the resulting files to make sure that each blend planes covers the full panorama. You can trick PTGui into recognizing your images as bracketed exposures by modifying the exposure data in the Image Parameters tab. If you took sets of 3 bracketed exposures, copy the exposure times of the first three images into the remaining images. The result should be a repeating sequence, e.g. 1/25, 1/100, 1/400, 1/25, 1/100, 1/400, and so on. Switch PTGui Pro to Advanced mode to make the Image Parameters tab visible.

However, the result will not be perfect. The automatic exposure has caused brightness differences between neighbouring images. The blender is able to make gradual adjustments, but it does not actually correct the exposure differences. Therefore we recommend to go back and take the bracketed images in manual exposure mode. The nice thing about HDR is that you don't need to worry anymore about proper exposure! By taking bracketed exposures, everything will be exposed properly in at least one of the images (provided the bracketing range is sufficiently wide). During HDR merging, the best part of every image is used in the final merged result. Over and underexposed pixels are discarded automatically. The Exposure Value (EV) recorded in the EXIF data (in the Exif 'exposure bias' field) indicates the difference between the actual exposure and the optimum exposure as measured by the camera's light sensor. In other words, it's the exposure offset the camera was instructed to use. It is not an absolute value and does not tell the actual amount of light captured.

On the other hand, the EV shown in PTGui Pro (Image Parameters tab) is calculated from the actual exposure data (exposure time, aperture and iso). This is the data that is used when generating HDR. The EV is a relative value, which can have an arbitrary offset. PTGui Pro offsets the EV such that the lowest EV equals zero minus the highest EV (i.e.: low = -high).

A difference between the displayed EV and the recorded EV can have two reasons: If you used auto bracketing in auto exposure mode, the camera has likely adjusted the base exposure time between each set of bracketed shots. In that case the bracketed sets themselves have an exposure offset within the panorama. A second reason is the limited choices of exposure times. For a +1 EV offset from 1/15s, most cameras will use 1/8s instead of 1/7.5s. The actual offset in this case is +0.9 EV. PTGui Pro can link images. Linked images have the same yaw, pitch, roll and other parameters. When a parameter of one such image is changed, the same changes are applied to the linked images. The optimizer treats the linked images as a single image and combines all control points of the linked images.

The link status of individual images is shown in the Image Parameters tab (visible in Advanced mode only). When the 'Link' checkbox of a certain image is enabled, the image is linked to the image directly above it. Linking is reciprocal: changes to image A are applied to image B, and changes to B are applied to A.

PTGui Pro can detect bracketed sets of images, and automatically link the images in each bracketed set. This is done by choosing 'Link HDR Bracketed Exposures' in the Images menu. For this to work, the exposure times of the images must follow a strictly repeating sequence, e.g. 1/25, 1/100, 1/400, 1/25, 1/100, 1/400, and so on. In this case, PTGui would recognize the sequence of 3 bracketed exposures each, and link each group of 3 images. If PTGui Pro doesn't recognize your bracketed exposures, the exposure times do not follow such a sequence; see Q9.3 above. If your images were taken from a sturdy tripod, with absolutely no camera movement within each bracketed set, it's best to link the exposures. This way, the bracketed images are guaranteed to be aligned with pixel accuracy. Furthermore it would not be a problem if a certain image is lacking control points, as long as the other images in the bracketed sets are linked by control points.

However, it's not necessary at all to link bracketed images. Linking only locks the image positions, PTGui Pro doesn't need linked images to create HDR. For that it only needs to know the exposure data of each image.

If the images were taken handheld, or if the camera may have moved between shots, the images should not be linked. In this case, PTGui Pro will attempt to align the images using control points. This is possible, but you need an image editing program capable of handling layered HDR files. As far as we know this can currently only be done in Photoshop CS3 Extended. The regular edition of Photoshop CS3 or earlier versions do not support 32 bit layers.

Also, PTGui Pro currently does not create layered HDR files but you can assemble one manually as follows:

• In PTGui Pro, Create Panorama tab, enable the HDR Panorama output component
• Also enable either the Individual HDR Layers or the HDR Blend Planes output components. The latter is sufficient for removing 'ghost' images of objects which moved while the bracketed images; the Individual HDR Layers give even more control.
• Choose 'HDR file format: Photoshop', settings: 32 bit
• After stitching, open all resulting files in Photoshop.
• In Photoshop, activate the HDR Panorama (called xxxx_hdr.psd). Right click on the 'Background' layer in the Layers palette and choose 'Layer from background'.
• Activate one of the other output files, press Ctrl+A, Ctrl+C (Windows) or Command+A, Command+C (Mac) to copy it to the clipboard
• Go back to the HDR Panorama file, and press Ctrl+V (Windows) or Command+V (Mac) to paste into a new layer
• In the menu bar, Choose Layer | Layer Mask | Hide All
• Repeat the previous three steps for all output components

The result is a layered HDR file, which can be edited in Photoshop CS3 Extended as described in the Post Processing tutorial. It's not necessary to use external applications since PTGui Pro can create HDR files. But if you prefer to use an external tool for merging to HDR, there are two ways to do this:

• First merge your bracketed source images to HDR files (.hdr or .exr format) in your external HDR application. Then load the HDR source images in PTGui. Please note that the control point generator currently is less sensitive when HDR source images are used, therefore you may need to add some control points manually.
• Or load all bracketed source images in PTGui. On the Create Panorama tab, enable only the 'Blend planes' output component (not to be confused with the 'HDR blend planes', see the online help). The blend planes can be loaded in an external application and merged to HDR

True HDR file formats (like .exr and .hdr) have a virtually unlimited dynamic range, they don't have a maximum brightness value that can be represented. On the other hand, 8 bit and 16 bit file formats do have a maximum brightness value of 255 and 65535, respectively. Any pixel brighter than this maximum would be clipped to the maximum allowed brightness. Clipped pixels are lost forever, reducing the brightness afterwards would not recover them. To prevent clipping when HDR data is written to 16 bit files, PTGui Pro reduces the brightness of the images such that the brightest pixel in all images does not exceed the maximum value of 65535.

Note that the 16 bit HDR output should be regarded as 'pseudo HDR': it can be used to edit layered HDR files in any 16 bit capable application. But if post processing is done in an HDR capable application, it's better to choose a true 32 bit HDR output format such as .hdr or .exr.