A novel technique for the scanned color image descreening

A quality of scanned color image is often hampered due the way images are printed. Usually electrophotographic printer prints the images by using halftoning technique wherein images are printed as a matrix of dots. This gives the illusion as images are printed as a perfect picture but behind the scene they are actually matrix of dots. So there is no problem as far as printed copies are considered, the real problem arise when such copies undergo scanning process. Scanned copies thus are affected by screen like artifacts and moiré patterns. The technique when applied on such images will produce clear scanned images. Technique consists of first separating the color image planes and then applying image redundancy based denoising algorithm to remove printing noise and to attenuate distortions. Then features such as screen frequency and local gradient are extracted to filter the image. This will remove halftone patterns in the scanned image. Finally edge preserving filtering is done to improve the sharpness of edges. Thus quality of resulting image will be better than the original image.