GIF stands for Graphics Interchange Format, a file format developed by Unisys. It is one of the main graphic formats displayed by Web browsers. GIFs store bitmaps in patterns of indexed color (256 colors or less) using a special algorithm called Lempel-Ziv-Welch (LZW). Using this algorithm, a GIF compresses the raw bitmaps into smaller file sizes. Because of their limited color depth, GIFs are better suited for images made up from solid colors such as logos, icons, and buttons. For photos, JPEG is a better choice.
If the file you are trying to save has more than 256 colors (like a True Color JPEG), FotoFinish will prompt you to convert your file to an optimized palette. The optimized palette is the minimum number of colors (up to 256) needed to preserve the original look of the image.
GIF conversion prompt
Choose Continue on the GIF Options dialog and FotoFinish will automatically save your image using a diffusion dithering pattern and an optimal color palette selected to suit your particular image. To manually convert your image to the appropriate color depth, click on Convert to choose your own dithering pattern and color settings in the Change Number of Colors dialog. (For more on dithering see the Understanding Color chapter.)
Manually converting GIF dithering and color settings
When saving a file as a GIF, you also have the option to set the background color as transparent. The background color refers to the current Background Color specified in the Tool Settings Panel, not necessarily the actual background color visible in your image. To set the current background color to transparent, check the box next to Save as Transparent in the Save as dialog.
Save a GIF with a transparent background color