Gimp
The GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. It works on many operating systems, in many languages.
The GIMP is designed to provide an intuitive graphical interface to a variety of image editing operations.
Here is a list of the GIMP's major features:
- Supports 8, 15, 16 and 24 bit color.
- Ordered and Floyd-Steinberg dithering for 8 bit displays
- View images as rgb color, grayscale or indexed color.
- Simultaneously edit multiple images.
- Zoom and pan in real-time.
- GIF, JPEG, PNG, TIFF XPM, etc … support.
- Image editing
- Selection tools including rectangle, ellipse, free, fuzzy, bezier and intelligent.
- Transformation tools including rotate, scale, shear and flip.
- Painting tools including bucket, brush, airbrush, clone, convolve, blend and text.
- Effects filters (such as blur, edge detect).
- Channel & color operations (such as add, composite, decompose).
- Plug-ins which allow for the easy addition of new file formats and new effect filters.
- Multiple undo-redo.