| Many people have asked me questions regarding color and the Internet, so I have made this section to help others understand how it works. If you have a graphics card with more than 2 meg of memory, then this section doesn't apply to you much. This is more for people with their monitors set to 256 colors.
Any color monitor is capable of viewing millions & billions of colors. The hardware that limits the number of colors you can view, is your graphics card.
Most new computers now come with graphics cards capable of viewing at least 16 millions colors, but if you buy a used computer or have an older one, you may only be able to have a total of 256 colors on the screen at a time. They can be any combination of colors, but only 256 colors can be displayed at one time. You will sometimes notice a flicker of weird colors when switching from one program to another.
To avoid this color swapping while surfing the net, Netscape & Internet Explorer have created a 216 color palette for their browsers. This default color palette was calculated mathematically and supposedly contains the 216 most common colors used on the net. Each image that is viewed on your screen is dithered to this default 216 color palette (both .gif or .jpg).
This means that if you have one gif image that was saved with 256 colors (default) and you view it in Netscape with a 256 color graphics card, at least 40 colors will be dropped from the image to make the 216. This is sometimes why your images will look much better in your paint program then in your web browser…you are dropping colors.
Once you create an image, there are two ways to save it: Adaptive palette & a specific palette.
Adaptive Palette - If you save an image as an 8-bit gif (default), The graphics program will analyze the image and pick the most frequent 256 colors that show up in the image. A 7-bit gif has only 128 colors, etc. For more information on gif bit depth, see this page. This is the best way to save a .GIF file if you want the most color out of it, but remember that if the person viewing this image on the net has a 256 color graphics card your image will be re-mapped to a 216 color palette and every computer will produce different results when viewed. To avoid this inconsistency, you can save your image with a specific palette.
Specific Palette - This is where you have an image and you save it to a specific color palette. In this case, Netscape’s or Microsoft's. You will need an .act .pal or .asf file to do this. These files are tiny in size and just store a list of 256 or less exact colors. You can do this with most programs. To do this in Photoshop, follow these steps:
1) Download this .zip file that contains the 4 different .pal files that you see to the left and place them on your hard drive.
2) Create your color image in RGB mode.
3) Go to IMAGE...MODE...INDEX COLOR (In Photoshop 4.0)
4) Select Custom... from the Palette drop down list, select your dither option and hit OK.
5) Click on the LOAD button from the Color Table and find the .ACT .ACO or .PAL file from your hard drive. Click OK.
6) Now save the .GIF file.
Your images won't have as many colors as a 256 color gif, but the image will look the same on all computers. There will be no guess work.
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