Mark Grundland: Color Histogram Specification by Histogram Warping

Color Histogram Specification by Histogram Warping

Web: www.Eyemaginary.com Email: Mark@Eyemaginary.com

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Citation:

Color Histogram Specification by Histogram Warping
Mark Grundland and Neil A. Dodgson
Proceedings of SPIE, vol. 5667, pp. 610-621, SPIE, (2005). ISBN 0819456403.
Presented as a poster at the Electronic Imaging Symposium, Color Imaging X: Processing, Hardcopy, and Applications (San Jose, USA, 17-20 January 2005).

Abstract:

Histogram warping is a novel histogram specification technique for use in color image processing. As a general purpose tool for color correction, our technique constructs a global color mapping function in order to transform the colors of a source image to match a target color distribution to any desired degree of accuracy. To reduce the risk of color distortion, the transformation takes place in an image dependent color space, featuring perceptually uniform color axes with statistically independent chromatic components. Eliminating the coherence between the color axes enables the transformation to operate independently on each color axis. Deforming the source color distribution to reproduce the dominant color features of the target distribution, the histogram warping process is controlled by designating the color shifts and contrast adjustments for a set of key colors. Assisted by mode detection, matching quantiles establish the correspondence between the color distributions. Interpolation by monotonic splines serves to extend the mapping over the entire dynamic range without introducing artificial discontinuities into the resulting color density. We show how our method can be applied to color histogram equalization as well as color transfer from an example image or a color palette.

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Examples:

Prevention of False Halo Artifacts

Problem: The ordering of colors is not preserved.

Solution: Apply monotonic interpolating splines.

Standard Mapping by Cubic Splines

Our Histogram Warping Technique

Prevention of False Contour Artifacts

Problem: The contrast changes too abruptly.

Solution: Apply continuously differentiable splines.

Standard Mapping by Linear Splines

Our Histogram Warping Technique

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Original Image 1	Original Image 2


Color Transfer from Image 2 to Image 1	Color Transfer from Image 1 to Image 2

Prevention of False Halo Artifacts
Problem: The ordering of colors is not preserved.	Solution: Apply monotonic interpolating splines.


Standard Mapping by Cubic Splines	Our Histogram Warping Technique

Prevention of False Contour Artifacts
Problem: The contrast changes too abruptly.	Solution: Apply continuously differentiable splines.


Standard Mapping by Linear Splines	Our Histogram Warping Technique