Color caching method used in color matching processing has advantages and disadvantages,
and the processing efficiency depends upon an image to be processed. In view of
this, color matching calculation and caching for uniquely determining an output
color corresponding to an input color are employed to calculate a hit rate per
unit block at a checkpoint block when performing color matching processing in block
unit having a predetermined pixel size. Based on the calculated hit rate, a caching
method to be applied to a block subsequent to the checkpoint block is determined.