1. A method, comprising the steps of: applying, by the processor, a spatial filter to a portion of an image, the spatial filter comprising a plurality of test regions; calculating, by the processor, for each of the test regions within the portion of the image a metric as a function of intensity within the test region; determining, by the processor, for the portion of the image a filter value based on the metrics of each of the test regions; and comparing, by the processor, the filter value with a threshold to identify a subsequent process that can be skipped.