Color Cell Compression

It is closely related to Block Truncation Coding,[4] another lossy image compression algorithm, which predates Color Cell Compression, in that it uses the dominant luminance of a block of pixels to partition said pixels into two representative colors.

Depending on whether an element of the bitmap is 1 or 0, one of the two 8-bit indices into the lookup table is selected and then dereferenced and the corresponding 24-bit per pixel color value is retrieved.

In spite of its very simple mechanism, the algorithm yields surprisingly good results on photographic images,[1][2][3] and it has the advantage of being very fast to decode with limited hardware.

Apple Video (RPZA) and S3 Texture Compression employ the same principle of encoding 4×4-pixel blocks based on two representative colors.

They refine CCC by expanding each entry in the luminance bitmap to two bits, where the additional two values represent a weighted average: one-third of one color and two-thirds of the other.