Restoration and enhancement of scanned document images
AssigneeHewlett-Packard Development Company, L.P.
InventorRon P. Maurer
Life of this patent
Estimating the term…
Abstract
Processing of a pixel in a digital image includes performing inverse halftoning on the pixel with respect to a local pixel neighborhood; and performing selective sharpening on the inverse halftoned pixel with respect to the local pixel neighborhood.
Claims19
A method of processing a pixel of a digital image, the method comprising:
- performing inverse halftoning on the pixel with respect to a local pixel neighborhood;
- and
- performing selective sharpening on the inverse halftoned pixel with respect to the local pixel neighborhood.
A method of processing a plurality of pixels of a digital image, the method comprising:
- determining local contrast information for the pixel;
- and
- performing inverse halftoning and variable contrast stretching on the pixel using the same local contrast information.
A method of processing a pixel of a digital image, the method comprising:
- performing inverse halftoning on the pixel;
- performing variable contrast mapping on the inverse halftoned pixel;
- and
- performing selective smoothing on the mapped pixel;
- the inverse halftoning, contrast mapping and selective smoothing performing complementary functions.
A system comprising:
- means for generating a scanned digital image, the scanned image including a plurality of pixel values;
- means for performing inverse halftoning on each pixel value of the plurality with respect to a local pixel neighborhood;
- and
- means for performing selective sharpening of the inverse halftoned pixel values by mapping the inverse halftone pixel values with respect to the same local pixel neighborhoods used during the inverse halftoning.
Apparatus for processing a pixel of a digital image, the apparatus comprising a processor for performing inverse halftoning on the pixel with respect to a local pixel neighborhood;
- and performing selective sharpening on the inverse halftoned pixel with respect to the local pixel neighborhood.
An article for instructing a processor to process a plurality of pixels of a digital image, the article comprising computer memory encoded with a program for instructing the processor to perform inverse halftoning on each pixel value of the plurality with respect to a local pixel neighborhood, and perform selective sharpening of the inverse halftoned pixel values by mapping the inverse halftone pixel values with respect to their local pixel neighborhoods.
Dependencies are inferred from the claim text.