Method for quantizing intra-block DC transform coefficients using the human visual characteristics

A method for quantizing intra-block DC transform coefficients for use in a digitized video signal encoder which provides an encoded video signal for transmission from an input digital video signal comprised of a plurality of equal-sized blocks, each of the blocks being either an inter-mode or an intra-mode video signal, said method comprising the steps of:

• converting each of the plurality of blocks included in the input digital video signal into a set of inter-block or intra-block DC and AC transform coefficients;
• selecting an intra-block DC transform coefficient from said set of inter-block or intra-block DC and AC transform coefficients;
• determining an intra-block DC quantizer step size for each set of a predetermined number of selected intra-block DC transform coefficients based on the selected intra-block DC transform coefficients included therein;
• and
• generating a quantized intra-block DC transform coefficient from each of the transform coefficients included in each set of the selected intra-block DC transform coefficients through the use of said intra-block DC quantizer step size.