1. A computer-implemented method of compressing a block of graphics image data into a compressed block, the block having a plurality of lines, each line having a plurality of columns, each column including a pixel, each pixel having a color represented by red, green, blue, and intensity values, the computer-implemented method comprising the steps of: (A) building an array of color ordinal numbers by identifying all colors present in the pixels of the block, each color ordinal number representing one of the colors, the array of color ordinal numbers comprising one of the color ordinal numbers corresponding to the color of a pixel for each pixel in the block; (B) storing the red, green, blue, and intensity values for a selected one of the colors in the compressed block; (C) building a first set of flags indicating lines in the block having pixels of the selected color according to the array of color ordinal numbers; (D) storing the first set of flags in the compressed block; (E) building at least one second set of flags indicating columns having pixels of the selected color within lines in the block having pixels of the selected color according to the array of color ordinal numbers, each line having pixels of the selected color being represented by one of the second set of flags; (F) storing the at least one second set of flags in the compressed block; and (G) repeating steps (B) through (F) for all colors in the block.