Web Design in a Nutshell, 3rd Edition

Work in RGB Mode

When you are creating graphics for the Web, it is important to work in the RGB color mode. CMYK mode, although common to the print world, is not appropriate for web graphics . JPEGs in CMYK mode may not display at all in some browsers.

If you work in Adobe Photoshop/ImageReady or Fireworks, it is easy to create and save an RGB original while merely exporting compressed JPEGs and indexed color GIFs or PNGs using the Save to Web or Export feature.

If you need to make an adjustment to an existing GIF, you should convert the color mode back to RGB before editing. This allows colors to be added from the full RGB spectrum to create blends and smooth text edges. If you work in index color mode, you will be limited to the colors in that GIF’s index color palette (which may only be a handful of pixel colors).

The only exceptions to this rule are black and white images , which you can edit in grayscale mode.