Free graphic viewer and photo viewer. Supports more than 200 graphics formats, and runs on many platforms. It has the features :

Import about 400 graphic file formats, Export about 50 graphic file formats
Multipage TIFF, Animated GIF, Animated ICO support
Image IPTC, EXIF metadata support
EXIF auto rotation support
IPTC editing, Resize, rotate, crop support
Lossless rotate & crop (jpeg) support
Adjust brightness, contrast...
Auto levels, contrast, Modify number of colors
Apply filters (blur, average, emboss, ...)
Apply effects (lens, wave, ...)
Fullscreen mode. Slide show with effects
Batch convert, batch rename
Create WEB page easily, Screen capture
Create contact Sheet, create or edit Multi-page file (TIFF, DCX, LDF)
TWAIN & WIA support (Windows only), Print support (Windows only)
Drag & Drop support (Windows only), Compare image side by side
Filmstrip layout, 44 languages support (Windows only)
And many many other things...