GS6

Weak noisy image compression. Works well for a smaller palette of colors or sparsely-populated noise. Two examples in the program show densly-packed, 8-color pixel noise (128x64 px) compressing to around 3.8k, while sparsely-packed (of same color & dimensions) pixel noise compresses to around 2k. The second listed value is the number of bytes needed to represent the image as a 4-bit-per-pixel bitmap, and the third listed value is the number of bytes needed for an equivalent GSAVE of the image. Fourth value is the fraction of bytes reduced by the compression, compared to the 4bpp bitmap. (Truncating the colors of the full sprite page to a palette size of 8 and compressing yields ~80k bytes.)

Instructions:

GS6 offsetX,offsetY,width,height,pixels_per_block,color_palette[]

GL6 offsetX,offsetY,inage_data[],copy_mode

Explanation and how-to-use in the program.