Circuit for sharpening of edges of a pixel image in a color copier

U.S. Patent Number: 5862266

Abstract: A circuit for sharpening a pixel image includes M accumulators which provide a rolling sum for each of a sequence of image pixel values. Each rolling sum comprises the sum of pixel values in the accumulator, all pixel values resident in the M accumulators comprising an array of pixel values, with one such accumulator including a central array pixel value. M inputs apply a sequence of at least N image pixel values to each of the M accumulators. Each sequence of N image pixel values is logically arrayed along a first dimension of the image and each sequence changes as each new image pixel value is input and an oldest image pixel value is removed. Each time a new image pixel is input to an accumulator, the accumulator outputs a new rolling sum of the image pixel values present therein. An arithmetic circuit determines from each set of M rolling sums, an average pixel value of the array of image pixel values, and then derives a difference between the central image pixel value and the average image pixel value. This arithmetic action arrives at a filtered central image pixel value which is substituted for the central image pixel value, thereby achieving a high boost filtering of the pixel image.

Inventors: Hunter; Paul E. (San Diego, CA)

Assignee: Hewlett-Packard Company (Palo Alto, CA)

Application Number: 08/659,814

Issued: 1999-01-19

Expired: 2007-01-19

Classes: 382/266 ; 382/205; 382/254

Field of search: 382/254,260,263,266,205 358/517,532 364/724.12

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