Abstract
The problem of registration of four-color half tone separations for color printing is addressed. We present a method to performautomatically registration of color separation films, a step currently performed manually by highly skilled professionals in the graphic arts printing industry.
An operator manually selects from the reference negative (generally CYAN) two windows with a digitizing cursor, and each window covering approximately 6 mm2 (0.25 in2) is digitized into a 640 × 640 array. On each negative and for each window, we extract the macro edges and approximate the contours by line segments. The segments from corresponding windows on different negatives are then matched with the reference ones to provide an estimate of the translation between them. The two translations (from the two windows) provide the parameters of the rigid planar transform between negatives (rotation and translation) and permit the punching of registration holes into the pictures for each negative.
The system has been implemented in the RegiStar® machine 1 built to perform the mechanical tasks associated with the algorithm. It is able to handle a set of fourcolor separations in about 5 minutes, from image acquisition to the punching of registration holes in the films maintaining an accuracy of 12μ (0.5 mil) for binary patterns and 25μ (1 mil) for true halftones. This speed is obtained by using an off-the-shelf Mercury array processor attached to an IBM personal computer.
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References
Ballard D, Brown C (1982) Computer Vision. Prentice-Hall, Englewood Cliffs, NJ
Canny J (1986) A computational approach to edge detection. IEEE Transactions on Pattern Analysis and Machine Intelligence 8(6): 679–698, (November)
Chen J, Huertas A, Medioni G (1987) Fast convolution with Laplacian-of-Gaussian masks. IEEE Transactions on Pattern Analysis and Machine Intelligence 9(4): 584–590, July
Clark JJ (1987) Singularities of contrast functions in scale space. In Proceedings of the 1st International Conference on Computer Vision. London, England, June, pp 491–495
Gazit S, Medioni G (1989) Accurate detection and linking of zero-crossings. Technical Report USC-IRIS 252, University of Southern California, Los Angeles, (April)
Haralick R (1984) Digital step edge from zero crossing of second directional derivatives. IEEE Transactions on Pattern Analysis and Machine Intelligence 6(1):58–68, January
Hough PVC (1962) Method and means for recognizing complex patterns. U.S. Patent 3069654, December 18
Huertas A, Medioni G (1986) Detection of intensity changes with subpixel accuracy using Laplacian-Gaussian masks. IEEE Transactions on Pattern Analysis and Machine Intelligence (5):651–664, (September)
Marr D, Hildreth E (1980) Theory of edge detection. In: Proceedings of the Royal Society of London. Vol. B207, pp 187–217
Medioni G (1983) Matching images using linear features. PhD Thesis Report USCISG 103 University of Southern California, Los Angeles, (August)
Nevatia R, Babu R (1980) Linear feature extraction and description. Journal of Computer Graphics and Image Processing 13:257–269
Pavlidis T (1982) Algorithms for graphics and image processing. Computer Science Press
Torre V, Poggio TA (1986) On edge detection. IEEE Transactions on Pattern Analysis and Machine Intelligence 8(8): 147–163, (March)
Ulupinar F, Medioni G (1988) Refining edges detected by a LoG operator. In: Proceedings of the Computer Vision and Pattern Recognition Conference. June, Ann Arbor, MI pp 202–207
Wilson M (1986) Machine vision in the graphics arts: Digital registration of four color halftone separations. In: Proceedings of the Technical Association of the Graphic Arts, pp 525–536
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Medioni, G., Huertas, A. & Wilson, M. Automatic registration of color separation films. Machine Vis. Apps. 4, 33–51 (1991). https://doi.org/10.1007/BF01240389
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DOI: https://doi.org/10.1007/BF01240389