If a color modes is a way of describing a digital image, a file format is a way of storing that information on a disk. There are a mid-numbing variety of file formats. The table below addresses a few of the most important for the aspiring Web author.
See also: GIF vs. JPEG
| Format | Web ready? | Bit-depth | Color modes | Compression | Transparency | Typical uses |
|---|---|---|---|---|---|---|
| GIF | Yes | Up to 8-bit | indexed, grayscale | Lossless | Simple | Cartoons, logos |
| JPEG | Yes | Up to 24-bit1 | RGB, grayscale, CMYK1 | Lossy | None | Photo- realistic images |
| PNG | Yes, but... | Up to 32-bit (24-bit plus alpha channel) | bitmap, grayscale, RGB | Lossless | Complex | ??? |
| Native | varies | |||||
| TIFF | No | Up to 32-bit (24-bit plus multiple masking channels) | bitmap, grayscale, indexed, RGB, CMYK, LAB | Optional, lossless | None | Inter- application exchange, archiving |
| PICT | No | Up to 32-bit (24-bit plus masking channel) | bitmap, grayscale, indexed, RGB | Optional, lossy | None | Macintosh exchange |
| BMP | No | up to 24-bit | bitmap, grayscale, indexed, RGB | Optional, lossless | None | PC exchange |
1 Caution: Some versions of the JPEG format can handle 32-bit, 4-channel (CMYK) color, but this is not compatible with the Web's RGB environment.