1. A method of inspection of an article comprising the steps of (a) digitizing the image of an article to be inspected to provide a first image array of first data values, each first data value being a digital representation of the intensity of the respective pixel of the image (b) transforming the first image array to a second image array of second data values, each second data value indicating the direction of the intensity gradient for each respective first data value (c) for each second data value of the second image array, determining a single third data value, each third data value being related to a respective second data value and responsive to the variability of the second data values within the neighborhood of that respective second data value, each neighborhood of each second data value being no more than a 3.times.3 neighborhood and being chosen so that each second data value has the same relative neighborhood location as each other respective second data value has to its neighborhood location, whereby the second image array is transformed into a third image array, and (d) characterizing the article being inspected utilizing, at least in part, the third data values.