Image analysis – Histogram processing – With a gray-level transformation
Patent
1993-10-07
1995-09-12
Razavi, Michael T.
Image analysis
Histogram processing
With a gray-level transformation
382274, 358522, 358447, G06T 540
Patent
active
054505020
ABSTRACT:
A method of improving the contrast in a natural scene image, in which the image is converted from an original set of color coordinates to an expression where one term has a relationship to overall image intensity. A global histogram of the image is derived for that term, which plots the populations of pixels at each possible level of intensity in the image. The signal describing the histogram is operated on with a filter having the characteristic of weakening strong peaks and valleys in the function, but not effecting flat portions of the signal. The filtered histogram signal is used for controlling the TRC mapping in a device at which the image is to be printed. Contrast is improved in areas likely to have the most image information, using the method described above, and further, dividing the image into a number of segments, each describable by a local histogram signal for that image segment. Each local histogram signal is compared to the global histogram, to determine which signals are flatter. If any of the local histograms have signals flatter than the global histogram, the signals are summed into a relevant histogram signal and directed to the flattening filter in its place.
REFERENCES:
patent: 3979555 (1976-09-01), Opittek et al.
patent: 3983320 (1976-09-01), Ketcham et al.
patent: 4805016 (1989-02-01), Kato
patent: 5150421 (1992-09-01), Morishita et al.
patent: 5164993 (1992-11-01), Capozzi et al.
patent: 5278641 (1994-01-01), Sekizawa et al.
R. C. Gonzlas and B. A. Fittes, "Gray level transformation for interactive image enhancement," Proc. Second Conference on Remotely Manned Systems, 1975.
E. L. Hall, "Almost uniform distributions for computer image enhancement," IEEE Trans. Comput. C-23, 207-208, 1974.
W. K. Pratt, Digital Image Processing, Wiley, N.Y., 1978.
M. P. Ekstrom, Digital Image Processing Techniques, Academic Press, Orlando, 1984 (J. S. Lim).
J. C. Russ, The Image Processing Handbook, CRC Press Boca Raton, 1992.
Pizer et al., "Adaptive Histogram Equalization and its Variations", Computer Vision, Graphics, and Image Processing, 39, 355-368 (1987), pp. 355-369.
"Xerox Color Encoding Standard," XNSS 289005, 1989.
Eschbach Reiner
Fuss William A.
Waldron Brian L.
Chang Jon
Costello Mark
Razavi Michael T.
Xerox Corporation
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