PTGui is a photo 
stiching application. Photo stiching
       involves perspectively
       correcting images, such that they can be assembled into panoramic images. A panoramic image consists of
       several images aligned such that they match exactly. It will look like an image shot with a wide angle
       lens.
       PTGui will seamlessly blend your images into a stitched panoramic photo. A free trial version is available,
       just click Download in the menu bar. PTGui runs on Windows and Mac OS X.
Features of PTGui:
- Create spherical, cylindrical or flat panoramas from any number of source images
 
- Supports jpeg, tiff, png and bmp source images
 
- WYSIWYG Panorama editor for interactive editing and realtime preview
 
- Stiching
 
- Supports many panoramic projections
 
- Create templates with frequently used settings
 
- Includes spherical panorama viewer and web publishing tool
 
PTGui originally started as a 
Graphical 
User 
Interface for Panorama Tools (hence the name). Over the years it has evolved into the most versatile stitching software. It easily gives you high quality stitched panoramas from overlapping images or photographs.
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Example

Stitched using PTGui:
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