Journal Article•
Automatic segmentation and descreening of scanned color documents
01 Jan 2001-Journal of Imaging Science and Technology (Society for Imaging Science and Technology)-Vol. 45, Iss: 5, pp 457-465
TL;DR: This technique speeds up the conversion process of books to digital form, and overcomes quality problems in the reproduction of halftoned images.
Abstract: Printing books-on-demand is a new technology that is revolutionizing the book printing and publishing industry. One of the biggest bottlenecks in this process is the conversion of existing books into digital form. This typically involves digitization of original books through scanning, which is a slow and labor-intensive process. Careful attention must be paid to maintain the quality of the reproduced books and in particular of the images they contain. Halftoned image areas in the original books cause the most reproduction problems, as there is the potential that moire patterns may form when these image areas are re-screened. In order to avoid these moire patterns, it is necessary to detect the image areas of the document and remove the screen pattern present in those areas. In the past, we have presented techniques to perform these operations in the case of grayscale images. In this article, we extend these techniques to handle color images. We present efficient and robust techniques to segment a color document into halftone image areas, detect the presence and frequency of screen patterns in halftone areas and suppress the detected screens. Halftoned image areas are segmented by using a measure of image activity; image activity is low in text areas and high in halftoned areas. We use 2-D Fourier spectral analysis to identify the screen frequencies present. The screens are then suppressed by low-pass filtering. Our technique speeds up the conversion process of books to digital form, and overcomes quality problems in the reproduction of halftoned images.
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12 May 2008
TL;DR: A scheme to automatically predict the presence of moire artifacts in the print-out before the actual printing take place and adaptive image processing can be applied to eliminate the potential artifact.
Abstract: With the introduction of the digital press in recent years, the cost of short-run printing jobs has decreased. The "print-on- the-fly" capability of these digital presses makes it possible to compose documents based on the contents extracted from various databases. The traditional proofing method in print shops focuses on human visual inspection of one hard copy among thousands of print-outs. However, in variable data printing (VDP), each instance of the same template could use different texts, fonts, and images obtained through various capturing devices. Visual inspection of every copy is not cost efficient in the VDP environment. In this paper, we present a scheme to automatically predict the presence of moire artifacts in the print-out before the actual printing take place. Only the images that may induce moire artifact with respect to the targeted press will be identified and adaptive image processing can be applied to eliminate the potential artifact.
Cites methods from "Automatic segmentation and descreen..."
...In order to distinguish strong periodic patterns from strong edges, we compute a measure of confidence [8] that describes the relative strength of theMIF in the power spectrum....
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