Image Processing Reference
GIF: Graphics Interchange Format
Unlike other file formats, the GIF format requires a color palette. This means
that a maximum of 256 colors can be saved in conjunction with an image.
GIMP can create these color palettes automatically, but there is a major
drawback to doing so. Converting images with an original color depth of 24
bits (or more) to GIF will usually produce an unsatisfactory result.
However, if you save an image with 256 or fewer colors (such as a simple
logo) to GIF, the GIF compression is lossless. In addition, GIF files allow you to
save one transparent color as well as simple animations ( animated GIF ).
The GIF format is often used to upload images to the Internet
• 2 to 256 colors, 8-bit color depth (at least one, possibly transparent, color)
• Lossless compression for images containing up to 256 colors
• Suitable for use on the Internet
• One color can be transparent
• Interlaced (immediate display, layered refresh rate in web pages)
• Animated GIF available
BMP: Windows Bitmap
Microsoft developed BMP, therefore it is supported by most Windows image
editing programs and is a suitable format for image sharing between different
programs. BMP has a color depth of 24 bits and the image resolution remains
unchanged when exporting. However, because the size of BMP files is normally
quite large, the format is not particularly suitable for the Internet.
• 16.78 million colors, 24-bit color depth
• Rather unsuitable for use on the Internet (for Microsoft Internet Explorer