Patent ID: 7295349

Claim:
A method for compensating for white space defects in a printed image, comprising: inputting image data usable to form the printed image; modifying the image data of at least one relatively lighter density region in the input image data to form modified image data, the modified image data compensated for a white space defect that would occur in that at least one region without compensation, the white space defect representing a diminished toner density region wherein modifying the input image data of at least one relatively lighter density region in the input image data comprises: (a) selecting a first scan line of the input image data as the current scan line; (b) identifying the current scan line as an historical scan line, the image value of each pixel of the current scan line defining an historical state value for that pixel, and storing the current scan line as a portion of the modified image data; (c) selecting a next scan line of the input image data as the current scan line; (d) selecting a first pixel in the current scan line as a current pixel; (e) determining a compensated image value for the current pixel based on an historical state value for that pixel and a current image value of that pixel; (f) determining an updated historical state value of the current pixel, the updated historical state value to be used as the historical state value for a corresponding pixel of a subsequent scan line; (g) storing the compensated input image value for the current pixel into the modified image data; (h) repeating steps (d)-(g) for each other pixel, in turn, of the current scan line until steps (d)-(g) have been repeated for a last pixel of the current scan line; and (i) repeating steps (c)-(h) for each subsequent scan line, in turn, of the input image data until steps (c)-(h) have been repeated for a last scan line of the input image data.