An image signal processor is described. The image signal processor includes a block checking circuit. The block checking circuit comprises comparison circuitry to compare a block of luminous pixel values against respective blocks of luminous pixel values that are processed by the image signal processor after the block of luminous pixel values. The block checking circuitry further comprises circuitry to record an entry in a table if one of the blocks of respective luminous pixel values match the block of luminous pixel values. The image signal processor is to store an image signal processing resultant of the block of luminous pixel values and present the stored resultant as a respective resultant for the one of the blocks of respective luminous pixel values if the one of the blocks of respective luminous pixel values matches the block of pixel values.