The simple answer is that the two systems handle colors in different ways. Although they both use a 256 color palette, the palettes do not include the same colors.
The Window's system palette reserves 20 colors for its use, and Netscape reserves 13 additional colors for its use.
Because these colors are being reserved for other uses, your system makes up the colors it can't use by dithering. To help reduce the problem, a 6 x 6 x 6 palette with the 216 colors common to the platforms has been made .
While the 216 palette is not a good choice for every image whose palette you reduce for the GIF format (especially photos and paintings) it can be very useful in many instances. For instance, when choosing background or font color tags in HTML, or when creating simple graphics like bullets, arrows, buttons, and text-based graphics.
Two places Web site that have created the 216 color palette in swatch form for use in PhotoShop. These can be downloaded from either:http://webreference.com/dev/graphics/palette.html or http://www.homepage.co.uk/webcolour/.
These helpful pages also include instructions for using the palette's and very detailed Web color information.
Below is a color chart of the 216 palette which includes the RGB values and the HEX code for each color.
| RGB 0, 0, 0 HEX 000000 |
RGB 0, 0, 51 HEX 000033 |
RGB 0, 0, 102 HEX 000066 |
RGB 0, 0, 153 HEX 000099 |
RGB 0, 0, 204 HEX 0000CC |
RGB 0, 0, 255 HEX 0000FF |
| RGB 0, 51, 0 HEX 003300 |
RGB 0, 51, 51 HEX 003333 |
RGB 0, 51, 102 HEX 003366 |
RGB 0, 51, 153 HEX 003399 |
RGB 0, 51, 204 HEX 0033CC |
RGB 0, 51, 255 HEX 0033FF |
| RGB 0, 102, 0 HEX 006600 |
RGB 0, 102, 51 HEX 006633 |
RGB 0, 102, 102 HEX 006666 |
RGB 0, 102, 153 HEX 006699 |
RGB 0, 102, 204 HEX 0066CC |
RGB 0, 102, 255 HEX 0066FF |
| RGB 0, 153, 0 HEX 009900 |
RGB 0, 153, 51 HEX 009933 |
RGB 0, 153, 102 HEX 009966 |
RGB 0, 153, 153 HEX 009999 |
RGB 0, 153, 204 HEX 0099CC |
RGB 0, 153, 255 HEX 0099FF |
| RGB 0, 204, 0 HEX 00CC00 |
RGB 0, 204, 51 HEX 00CC33 |
RGB 0, 204, 102 HEX 00CC66 |
RGB 0, 204, 153 HEX 00CC99 |
RGB 0, 204, 204 HEX 00CCCC |
RGB 0, 204, 255 HEX 00CCFF |
| RGB 0, 255, 0 HEX 00FF00 |
RGB 0, 255, 51 HEX 00FF33 |
RGB 0, 255, 102 HEX 00FF66 |
RGB 0, 255, 153 HEX 00FF99 |
RGB 0, 255, 204 HEX 00FFCC |
RGB 0, 255, 255 HEX 00FFFF |
| RGB 51, 0, 0 HEX 330000 |
RGB 51, 0, 51 HEX 330033 |
RGB 51, 0, 102 HEX 330066 |
RGB 51, 0, 153 HEX 330099 |
RGB 51, 0, 204 HEX 3300CC |
RGB 51, 0, 255 HEX 3300FF |
| RGB 51, 51, 0 HEX 333300 |
RGB 51, 51, 51 HEX 333333 |
RGB 51, 51, 102 HEX 333366 |
RGB 51, 51, 153 HEX 333399 |
RGB 51, 51, 204 HEX 3333CC |
RGB 51, 51, 255 HEX 3333FF |
| RGB 51, 102, 0 HEX 336600 |
RGB 51, 102, 51 HEX 336633 |
RGB 51, 102, 102 HEX 336666 |
RGB 51, 102, 153 HEX 336699 |
RGB 51, 102, 204 HEX 3366CC |
RGB 51, 102, 255 HEX 3366FF |
| RGB 51, 153, 0 HEX 339900 |
RGB 51, 153, 51 HEX 339933 |
RGB 51, 153, 102 HEX 339966 |
RGB 51, 153, 153 HEX 339999 |
RGB 51, 153, 204 HEX 3399CC |
RGB 51, 153, 255 HEX 3399FF |
| RGB 51, 204, 0 HEX 33CC00 |
RGB 51, 204, 51 HEX 33CC33 |
RGB 51, 204, 102 HEX 33CC66 |
RGB 51, 204, 153 HEX 33CC99 |
RGB 51, 204, 204 HEX 33CCCC |
RGB 51, 204, 255 HEX 33CCFF |
| RGB 51, 255, 0 HEX 33FF00 |
RGB 51, 255, 51 HEX 33FF33 |
RGB 51, 255, 102 HEX 33FF66 |
RGB 51, 255, 153 HEX 33FF99 |
RGB 51, 255, 204 HEX 33FFCC |
RGB 51, 255, 255 HEX 33FFFF |
| RGB 102, 0, 0 HEX 660000 |
RGB 102, 0, 51 HEX 660033 |
RGB 102, 0, 102 HEX 660066 |
RGB 102, 0, 153 HEX 660099 |
RGB 102, 0, 204 HEX 6600CC |
RGB 102, 0, 255 HEX 6600FF |
| RGB 102, 51, 0 HEX 663300 |
RGB 102, 51, 51 HEX 663333 |
RGB 102, 51, 102 HEX 663366 |
RGB 102, 51, 153 HEX 663399 |
RGB 102, 51, 204 HEX 6633CC |
RGB 102, 51, 255 HEX 6633FF |
| RGB 102, 102, 0 HEX 666600 |
RGB 102, 102, 51 HEX 666633 |
RGB 102, 102, 102 HEX 666666 |
RGB 102, 102, 153 HEX 666699 |
RGB 102, 102, 204 HEX 6666CC |
RGB 102, 102, 255 HEX 6666FF |
| RGB 102, 153, 0 HEX 669900 |
RGB 102, 153, 51 HEX 669933 |
RGB 102, 153, 102 HEX 669966 |
RGB 102, 153, 153 HEX 669999 |
RGB 102, 153, 204 HEX 6699CC |
RGB 102, 153, 255 HEX 6699FF |
| RGB 102, 204, 0 HEX 66CC00 |
RGB 102, 204, 51 HEX 66CC33 |
RGB 102, 204, 102 HEX 66CC66 |
RGB 102, 204, 153 HEX 66CC99 |
RGB 102, 204, 204 HEX 66CCCC |
RGB 102, 204, 255 HEX 66CCFF |
| RGB 102, 255, 0 HEX 66FF00 |
RGB 102, 255, 51 HEX 66FF33 |
RGB 102, 255, 102 HEX 66FF66 |
RGB 102, 255, 153 HEX 66FF99 |
RGB 102, 255, 204 HEX 66FFCC |
RGB 102, 255, 255 HEX 66FFFF |
| RGB 153, 0, 0 HEX 990000 |
RGB 153, 0, 51 HEX 990033 |
RGB 153, 0, 102 HEX 990066 |
RGB 153, 0, 153 HEX 990099 |
RGB 153, 0, 204 HEX 9900CC |
RGB 153, 0, 255 HEX 9900FF |
| RGB 153, 51, 0 HEX 993300 |
RGB 153, 51, 51 HEX 993333 |
RGB 153, 51, 102 HEX 993366 |
RGB 153, 51, 153 HEX 993399 |
RGB 153, 51, 204 HEX 9933CC |
RGB 153, 51, 255 HEX 9933FF |
| RGB 151, 102, 0 HEX 996600 |
RGB 153, 102, 51 HEX 996633 |
RGB 153, 102, 102 HEX 996666 |
RGB 153, 102, 153 HEX 996699 |
RGB 153, 102, 204 HEX 9966CC |
RGB 153, 102, 255 HEX 9966FF |
| RGB 153, 153, 0 HEX 999900 |
RGB 153, 153, 51 HEX 999933 |
RGB 153, 153, 102 HEX 999966 |
RGB 153, 153, 153 HEX 999999 |
RGB 53, 153, 204 HEX 9999CC |
RGB 153,153, 255 HEX 9999FF |
| RGB 153, 204, 0 HEX 99CC00 |
RGB 153, 204, 51 HEX 99CC33 |
RGB 153, 204, 102 HEX 99CC66 |
RGB 153, 204, 153 HEX 99CC99 |
RGB 153, 204, 204 HEX 99CCCC |
RGB 153, 204, 255 HEX 99CCFF |
| RGB 153, 255, 0 HEX 99FF00 |
RGB 153, 255, 51 HEX 99FF33 |
RGB 153, 255, 102 HEX 99FF66 |
RGB 153, 255, 153 HEX 99FF99 |
RGB 153, 255, 206 HEX 99FFCC |
RGB 155, 255, 255 HEX 99FFFF |
| RGB 204, 0, 0 HEX CC0000 |
RGB 204, 0, 51 HEX CC0033 |
RGB 204, 0, 102 HEX CC0066 |
RGB 204, 0, 153 HEX CC0099 |
RGB HEX CC00CC |
RGB 204, 0, 255 HEX CC00FF |
| RGB 204, 51, 0 HEX CC3300 |
RGB 204, 51, 102 HEX CC3333 |
RGB 204, 51, 152 HEX CC3366 |
RGB 204, 51, 153 HEX CC3399 |
RGB 204, 51, 204 HEX CC33CC |
RGB 204, 51, 255 HEX CC33FF |
| RGB 204, 102, 0 HEX CC6600 |
RGB 204, 102, 51 HEX CC6633 |
RGB 204, 102, 102 HEX CC6666 |
RGB 204, 102, 153 HEX CC6699 |
RGB 204, 102, 204 HEX CC66CC |
RGB 204, 102, 255 HEX CC66FF |
| RGB 204, 153, 0 HEX CC9900 |
RGB 204, 153, 51 HEX CC9933 |
RGB 204, 153, 102 HEX CC9966 |
RGB 204, 153, 153 HEX CC9999 |
RGB 204,153, 204 HEX CC99CC |
RGB 204, 153, 255 HEX CC99FF |
| RGB 204, 204, 0 HEX CCCC00 |
RGB 204, 204, 51 HEX CCCC33 |
RGB 204, 204, 102 HEX CCCC66 |
RGB 204, 204, 153 HEX CCCC99 |
RGB 204, 204, 204 HEX CCCCCC |
RGB 204, 204, 255 HEX CCCCFF |
| RGB 204, 255, 0 HEX CCFF00 |
RGB 204, 255, 51 HEX CCFF33 |
RGB 204, 255, 102 HEX CCFF66 |
RGB 204, 255, 153 HEX CCFF99 |
RGB 204, 255, 204 HEX CCFFCC |
RGB 204, 255, 255 HEX CCFFFF |
| RGB 255, 0, 0 HEX FF0000 |
RGB 255, 0, 51 HEX FF0033 |
RGB 255, 0, 102 HEX FF0066 |
RGB 255, 0, 153 HEX FF0099 |
RGB 255, 0, 204 HEX FF00CC |
RGB 255, 0, 255 HEX FF00FF |
| RGB 255, 51, 0 HEX FF3300 |
RGB 255, 51, 51 HEX FF3333 |
RGB 255, 51, 102 HEX FF3366 |
RGB 255, 51, 153 HEX FF3399 |
RGB 255, 51, 204 HEX FF33CC |
RGB HEX FF33FF |
| RGB 255, 102, 0 HEX FF6600 |
RGB 255, 102, 51 HEX FF6633 |
RGB 255, 102, 102 HEX FF6666 |
RGB 255, 102, 153 HEX FF6699 |
RGB 255, 102, 204 HEX FF66CC |
RGB 255, 102, 255 HEX FF66FF |
| RGB 255, 153, 0 HEX FF9900 |
RGB 255, 153, 51 HEX FF9933 |
RGB 255, 153, 102 HEX FF9966 |
RGB 255, 153, 153 HEX FF9999 |
RGB 255, 153, 204 HEX FF99CC |
RGB 255, 153, 255 HEX FF99FF |
| RGB 255, 204, 0 HEX FFCC00 |
RGB 255, 204, 51 HEX FFCC33 |
RGB 255, 204, 102 HEX FFCC66 |
RGB 255, 204, 153 HEX FFCC99 |
RGB 255, 204, 204 HEX FFCCCC |
HEX FFCCFF |
| RGB 255, 255, 0 HEX FFFF00 |
RGB 255, 255, 51 HEX FFFF33 |
RGB 255, 255, 102 HEX FFFF66 |
RGB 255, 255, 153 HEX FFFF99 |
RGB 255, 255, 206 HEX FFFFCC |
RGB 255, 255, 255 HEX FFFFFF |
| The Graphics Technology Cookbook text links |
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| Digital cameras desktop video and sound |
Web pages | Class handouts and PDF instructions |
Images scanning and printing |
Slides and presentations |
Multimedia and Authoring |
NewMedia User Web Site |