Patent ID: 7333672

Claim:
A method of image processing comprising (a) receiving image data; (b) processing the received image data to identify one or more significant regions having a higher high spatial frequency content than does the remainder of the image; and then (c) performing a subsequent recognition process upon the image data received in step (a), the subsequent recognition process being limited to said identified regions; wherein step (b) comprises: creating measures of high spatial frequency activity as a function of position with the image, comparing the measures with a threshold value, and signalling as significant regions those parts of the image having values of the measure which is indicative of greater high spatial frequency activity than the threshold value; wherein the measures are created by applying a high-pass spatial filtering operation to the image in two different directions to produce first and second measures; combining the first and second measures to produce a third measure; and applying a low-pass spatial filtering operation to the third measure; and wherein applying the low-pass spatial filtering operation merges neighboring areas of high spatial frequency activity.