Patent ID: 7502414

Claim:
A picture processing apparatus comprising: transforming means for performing a transforming process for picture data in the unit of a transforming block and outputting transformed coefficients as a result of the transforming process; sub block forming means for forming a sub block from the transforming block; activity detecting means for calculating an activity in the unit of a plurality of sub blocks contained in the transforming block of the picture data and outputting an activity of a block composed of the plurality of transforming blocks with the activity of each of the sub blocks; and quantizing means for deciding a quantizer scale of the block according to the activity output from the activity detecting means and quantizing the transformed coefficients output from the transforming means with the quantizer scale, wherein the activity detecting means comprises: means for obtaining an average value of levels of pixels for each sub block; means for obtaining an absolute value of a difference value between the level of the pixel and the average value for each pixel; means for obtaining an average difference value of the absolute values of the difference values for each sub block; and means for selecting a minimum value from the average difference values of the block and using the selected minimum value as the activity of the block.