Production of an image model and inspection of a pixel representation of an image

摘要

A method of inspecting a pixel for tolerable variation from a corresponding selected pixel in a master image comprises establishing a data word of which the bits each indicate whether or not all the master image pixels in the neighborhood of the selected pixel all have values (i.e. brightness values) within a respective range. A data word representing the value of the inspected pixel is compared simultaneously with the ranges of values associated with the bits of the data word, which provides gating for the comparisons.