Pixel Based

File Formats

Advantages Other Features Non-Lossy Compression?
gif Browser Readable only 256 colors, smaller file sizes, (proprietary) YES
jpg Browser Readable Lossy Compression no
png Browser Readable patent-free replacement for GIF and can also replace many common uses of TIFF. Indexed-color, grayscale, and truecolor images are supported, plus an optional alpha channel for transparency. Not support by older browsers. YES
tif Can include layers non-proprietary, good non-lossy compression YES
psd Can include layers Photoshop Only (proprietary) NA
xcf Can include layers GIMP Only NA
bmp Used by many Windows applications. can include layers Uncompressed, large file sizes Not compressed
       

Some Basic Guidelines

Use GIF or PNG for line art type images (mono chromatic poster type images)
reduce colors where possible using Mode command

Use JPG for web or powerpoint presentations when continuous color tone is desired.
Try to keep images less than 100k for web.

Use TIF for final (flattened) printwork (300 DPI is usually sufficient for most 8"x10" work)

Use xcd format (GIMP) while under construction