![]() ![]() Dithering often causes a visible and objectionable dotted or Palette, then dots of other palette colors are mixed to simulate the color. If the one exact shade of pink is not in the Representing a color by combinations of dots of other colors. Or show colors not in that limited palette. Two choices are required, to specify a palette of colors, and also a choice how to dither There are several ways to convert to indexed color. This palette choice affects the image greatly. There are various ways to create the palette, toĬhoose the possible color choices that it will contain. Image programs will show the palette for indexed images, and can modify palette colors. So, GIF would not be used for color photo images today. But JPG compression can reduce this file size substantially, and 24-bit RGB can show 16.7 million colors, instead of only 256 colors. ![]() In comparison, a 24-bit RGB image would store 24 bits RGB for each pixel (3x more size than 8 bit indexed), but without the 256-color 24-bit palette (only 768 bytes). Each pixel only stores either a 4 bit or 8 bit index to So indexed files have 24 bits stored for each palette color, but not for each pixel. The first RGB color in the table is index 0, the second RGB color is index 1, etc. ![]() The file also contains the palette too, which is the table of the selected 24 bit colors, or 3 bytes of RGB overhead for each color in the So if you count four colors, assume 8 or 16 colors will make it look a little better. Not that the graphics may appear to have only say four colors, but any sharp edges (like say on text characters) are aliased, adding a few new intermediate shades of the colors, blending the edges so that the jaggies don't show. The 8 bit size for the index for each pixel. The size of many graphics files can be limited to use 16 colors, which only uses 4 bit indexes, making the file smaller yet, half But an 8 bit number can only contain a numerical value of 0 to 255, so only 256 colors can be in the palette of The index might be a 4 bit value (16 colors in palette) or a 8 bit value (256 colors in palette) for each pixel, the idea being that this is much smaller than The palette is stored in the file with the image.īits in index Colors in Palette 1 2 Line artĢ 4 3 8 4 16 5 32 6 64 7 128 8 256 Or 8 bit grayscale We have to go to the palette to see what color is there. Number that specifies one of the palette colors, like maybe "color number 82", where 82 is the index into the palette, the 82nd color Images areĬalled indexed color because the actual image data for each pixel is the index into this palette. Each color used is a 24 bit RGB value.Įach such image file contains its own color palette, which is a list of the selected 256 colors (or fewer colors in a smaller palette). Indexed Color is limited to 256 colors, which can be any 256 colors from the set of 16.7 million 24 bit colors. ![]()
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