Pablo Picasso’s Lovers. a) Color image (courtesy of Artcyclopedia.com). b)–e) Grayscale images with
their per-pixel contrast RWMS error images (g)–(j), respectively. (b) Luminance image. (c) Grayscale image
produced by the Gooch et al. method using its default parameters. (d) A grayscale image produced by the
Rasche et al. approach. Note that it is hard to distinguish between the lady’s yellow skirt and the man’s
red clothes. (e) Grayscale image produced by our approach. (f) Error scale, where red indicates a larger error.
An Improved Contrast Enhancing Approach for Color-to-Grayscale Mappings
Giovane R. Kuhn
grkuhn@inf.ufrgs.br

Manuel M. Oliveira
oliveira@inf.ufrgs.br

Leandro A. F. Fernandes
laffernandes@inf.ufrgs.br

Instituto de Informática, UFRGS

Logo INFLogo UFRGS

The Visual Computer.
Volume 24, Numbers 7-9, July 2008, pp. 505-514. [DOI]


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Abstract Downloads Reference Acknowledgments

Abstract

Despite the widespread availability of color sensors for image capture, the printing of documents and books are still primarily done in black-and-white for economic reasons. In this case, the included illustrations and photographs are printed in grayscale, with the potential loss of important information encoded in the chrominance channels of these images. We present an efficient contrast enhancement algorithm for color-to-grayscale image conversion that uses both luminance and chrominance information. Our algorithm is about three orders of magnitude faster than previous optimization-based methods, while providing some guarantees on important image properties. More specifically, our approach preserves gray values present in the color image, ensures global consistency, and locally enforces luminance consistency. Our algorithm is completely automatic, scales well with the number of pixels in the image, and can be efficiently implemented on modern GPUs. We also introduce an error metric for evaluating the quality of color-to-grayscale transformations.

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Reference

Citation

Kuhn, Giovane R., Manuel M. Oliveira and Leandro A. F. Fernandes. "An improved contrast enhancing approach for color-to-grayscale mappings"The Visual Computer. Volume 24 (2008), Numbers 7-9,  pp. 505-514.

BibTeX

@article {springerlink:10.1007/s00371-008-0231-2,
   author = {Giovane R. Kuhn and Manuel M. Oliveira and Leandro A. F. Fernandes},
   title = {An improved contrast enhancing approach for color-to-grayscale mappings},
   journal = {The Visual Computer},
   pages = {505-514},
   volume = {24},
   issue = {7},
   year = {2008}
}

Keywords

Color reduction, Color-to-grayscale, Image processing, Error metric.

Acknowledgments

CNPq-Brazil fellowships and grants #305613/2007-3, 142627/2007-0.