The image data compression method involves the performing of steps: a block dividing step for dividing a computer processor pipeline statistic image to be displayed into a plurality of blocks with predetermined block width and block height; a block list creating step for creating a block list for indexed blocks containing meaningful pixels in the divided blocks such that the indexed blocks are associated with each other, wherein the meaningful pixels are pixels corresponding to the computer processor pipeline raw trace data; and a pixel information compressing step for compressing original pixel information on the meaningful pixels in the indexed blocks and storing it in the block list. Apparatus for performing the method is also provided.