Patent ID: 7453938

Claim:
A quantizer selection method, comprising: calculating a normalized average activity level of a picture from on image information of the picture, adjusting a base quantizer value according to the picture's normalized average activity level, and selecting a quantizer value for the picture based on the adjusted quantizer value, wherein the calculating comprises: for a plurality of macroblocks in the picture, calculating variances of image data for a plurality of blocks therein, from minimum variance levels of the macroblocks, calculating minimum activity levels of the macroblocks, wherein the minimum activity of each macroblock is calculated as: actmin=1+min(blkvar1, blkvar2, blkvar3, blkvar4), where blkvar represents the variances of 8×8 blocks within a respective macroblock, and normalizing the minimum activity levels of the macroblocks, wherein the normalized minimum activity per macroblock is calculated as: actnorm = ( 2 × act ⁢ ⁢ min ) + act ⁢ ⁢ min ⁢ ⁢ avg act ⁢ ⁢ min + ( 2 × act ⁢ ⁢ min ⁢ ⁢ 8 ⁢ ⁢ avg ) where actminavg is a sum of actmin values for all macroblocks in a previously processed picture and the actnorm values for all macroblocks in the picture are averaged to obtain the normalized average activity level of the picture.