only slight fig3 shows a conceptual drawing of the encoding scheme illustrating a 4 color and 4 u00d7 4 matrix size combination which could be one of the switchable coder chips 14 39 fig1 the block size has been doubled over that of fig2 and the number of colors has been doubled the coding efficiency has been shown to remain constant as an example in the case of four colors per block there could be determined highest value of luminance the lowest value of luminance and the median 1 and median 2 values of luminance comparators then would be used to find and separate those pixels that are closest to the high value i e color d those that are closest to the low value color a and those that are closest to the median values colors b and c the bit map then would be a variable number of bits per pixel either 1 bit 2 bits or 3 bits as follows referring to fig4 there is shown a functional flow diagram of the decompressor decoder basically the flow is in reverse order from the encoder compressor the decompressor 21 involves reconstructing each frame from the frame bit map and placing it into frame memory 22 then block bit map is used to decode the color values with reference to.