Block-based image compression method and apparatus

Abstract

A block-based image compression method and encoder/decoder circuit compress a plurality of pixels in a block where each pixel includes a corresponding color value and a corresponding luminance value. The encoder circuit includes a luminance-level-based representative color generator to generate representative color values for each of a plurality of luminance levels to produce at least a high color value and a low color value. In response to generating the representative color values, the luminance-level-based representative color generator associates each of the pixels in the block with one of the plurality of representative color values to produce corresponding bitmap values. The encoder circuit further includes a color type block generator to perform at least one of: (a) generate block color data indicating a regular/alternate color block type and (b) representing a block color type by ordering the representative color values that are to be sent to a decoder. The alternate color type block data is generated based on at least comparing the representative low color value to a first brightness threshold and comparing the high color value to a second brightness threshold.