Abstract: A frame of digitized video data is compressed by dividing the frame into a plurality of rectangular blocks each typically measuring 4 pixels by 4 pixels. The entropy of each block is determined by measuring the difference between a maximum luminance of any pixel in the block and the minimum luminance of any pixel in the block. Those blocks which have a luminance value above a predetermined threshold (such as the average luminance for the block) are then subdivided into four blocks each including four pixels. Then, for each sub-block of 4 pixels a conventional video color compression technique is applied. For the non-subdivided blocks i.e., where the maximum luminance difference is below the threshold, the entire block is video compressed into a high color value and a low color value which are typically averages of the higher luminance and lower luminance group pixels respectively.

Abstract: An anti-clipping mixer circuit is provided within an integrated circuit. The mixer circuit allows for the independent level control of each input signal, thereby allowing the optimization of the signal-to-noise ratio. A master level control is provided to limit the overall combined output signal to a level below the operational amplifier's maximum voltage level. A control circuit may be used to automatically adjust the input signal levels as well as the combined output signal level.