United States Patent [m
[i l] Patent Number:  Date of Patent:
 METHOD AND APPARATUS FOR
RECONSTRUCTING MISSING COLOR
 Inventor: William T. Freeman, Brookline, Mass.
 Assignee: Polaroid Corporation, Cambridge, Mass.
 Appl.No.: 88,801
 Filed: Aug. 24, 1987
 Int. CU H04N9/04
 U.S. CI 358/41; 358/36
 Field of Search 358/41, 43, 44, 36;
 References Cited
U.S. PATENT DOCUMENTS
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4,605,956 8/1986 Cole 358/44
4,613,986 9/1986 Ataman et al 382/54
4,630,307 12/1986 Cole 382/54 X
4,663,655 5/1987 Freeman 358/41
4,682,230 7/1987 Perlman et al 358/36 X
"An Image Processing System for Enhancement and Deblurring of Photographs", by Dr. A. F. Lehar, Dr. F. H. Preston and Dr. T. M. Cannon, International Conference on Electronic Image Processing, Institute
of Electrical Engineers, Conference Publication No. 214, Jul. 1982, pp. 174-178.
"One-Dimensional Processing for Adaptive Image Restoration", by P. Chan & J. Lim, ICASSP 84 Proceedings, IEEE International Conference on Acoustics, Speech and Signal Processing, San Diego, Mar. 1984, Paper 37.3.
"A Separable Median Filter for Image Noise Smoothing", by P. Narendra, IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. PAMI-3, No. 1, Jan. 1981, pp. 20-29.
Primary Examiner—James J. Groody
Assistant Examiner—E. Anne Faris
Attorney, Agent, or Firm—Edward S. Roman
An improved method and apparatus is provided for sensing scene light and providing sampled image data in three colors in response thereto. The sampled image data is subsequently interpolated for the non-sampled colors and thereafter subtracted to provide two color difference signals. The two color difference signals, in turn, are each median filtered and subsequently reconstructed in conjunction with the originally sampled image data to provide an image of the subject with substantially reduced color fringing. The median filter preferably filters color difference signals corresponding to a select number of image sensing elements separated with respect to each other by non-select image sensing elements.
21 Claims, 3 Drawing Sheets