NConvert is a batch software for converting graphic files. The softwre is cross-platform and is able to handle more than 400 graphical file formats.

Features:

Import about 400 graphic file formats

Export about 40 graphic file formats

Multipage TIFF, Animated GIF, Animated ICO support

Resize

Adjust brightness, contrast...

Modify number of colors

Apply filters (blur, average, emboss, ...)

Apply effects (lens, wave, ...)

And many many other things...

Editor's note: This is a command line tool. Knowledge of using DOS (command prompt) is needed.