EVALUATION OF COLOR-TO-GRAYSCALE CONVERSIONS

Chief investigator: Martin Čadík, email: cadikm@centrum.cz, homepage: http://cadik.posvete.cz/

Project web page: http://cadik.posvete.cz/color_to_gray_overview/

Project description:

The goal of the project is an overview and evaluation of state-of the art color-to-grayscale image conversions. We conduct both the subjective and objective comparisons of the methods using LDR and HDR benchmarks.

Black-and-white photography has not lost any of its artistic appeal despite the wide availability of color imaging processes. Accordingly, the conversion from color to grayscale is an important piece of the computational photography puzzle. Furthermore, color images often have to be converted to grayscale for reproduction, or for subsequent processing. To that end, color-to-grayscale conversions basically perform a reduction of the three dimensional color data into one dimension. The aim of color-to-grayscale conversions is usually to produce perceptually plausible grayscale results. Unfortunately, no analogous conversion is naturally present in the human visual system (HVS). However, one may measure perceptual differences between colors in subjective psychophysical experiments. Moreover, it is evident that some loss of information due to the conversion is inevitable. The other goal is therefore to reproduce maximum information from the original color image in the grayscale.

In conventional black-and-white photography, gray tones are determined by the spectral sensitivity of the emulsion, and can be modified in an active way by selecting different filters to enhance a specific part of the spectrum. This analog multispectral technique can now be emulated digitally, and this approach to the problem can be considered as a global color-to-gray conversion. Additionally, local approaches to color-to-grayscale conversion have been proposed. These are conceptually similar to local HDR tone mapping methods, because they aim at preserving color contrasts by introducing chrominance information locally into the luminance channel. Unfortunately, this may also lead to undesirable artifacts, and high computational complexity.


COLOR-TO-GRAYSCALE IMAGE CONVERSION

Color-to-grayscale Conversion


IMPLEMENTED CONVERSIONS

Original image Grayscale result Conversion description
   

CIE Y channel




   

Raja Bala, Reiner Eschbach

Spatial Color-to-Grayscale Transform Preserving Chrominance Edge Information

Spatial Color-to-Grayscale Transform Preserving Chrominance Edge Information


   

Amy A. Gooch, Sven C. Olsen, Jack Tumblin, Bruce Gooch

Color2Gray: Salience-Preserving Color Removal

Color2Gray: Salience-Preserving Color Removal


   

K. Rasche, R. Geist, J. Westall

Re-coloring Images for Gamuts of Lower Dimension

Detail Preserving Color Transformation


   

Mark Grundland, Neil A. Dodgson

Decolorize: Fast, Contrast Enhancing, Color to Grayscale Conversion

Decolorize: Fast, Contrast Enhancing,Color to Grayscale Conversion


   

Laszlo Neumann, Martin Cadik, Antal Nemcsics

An Efficient Perception-Based Adaptive Color to Gray Transformation

Perceptually-Plausible Conversion of Images to Grayscale


   

Kaleigh Smith, Pierre-Edouard Landes, Jöelle Thollot, Karol Myszkowski

Apparent Greyscale: A Simple and Fast Conversion to Perceptually Accurate Images and Video

Apparent Greyscale: A Simple and Fast Conversion to Perceptually Accurate Images and Video


   

Yongjin Kim, Cheolhun Jang, Julien Demouth, Seungyong Lee

Robust Color-to-gray via Nonlinear Global Mapping

Project webpage


   

Zhinan Xu, Julien Demouth, Seungyong Lee

Optimization-based Image Decolorization

Code on github


   

Soonmin Bae, Sylvain Paris, Fredo Durand Julien Demouth, Seungyong Lee

Two-scale Tone Management for Photographic Look

Project webpage


   

Cosmin Ancuti, Codruta O. Ancuti

Laplacian-guided image decolorization

Project webpage




METHODS TO IMPLEMENT (i.e. possible student projects/master's thesis topics)

   TODO  

David Hafner and Joachim Weickert

Variational Image Fusion with Optimal Local Contrast


http://www.mia.uni-saarland.de/Research/Image_Fusion/index.shtml
   TODO

Raja Bala, Karen M. Braun

Color-to-Grayscale Conversion to Maintain Discriminability

Color-to-Grayscale Conversion to Maintain Discriminability


   TODO

Baldrich, R., Vanrell, M., Benavente, R., Salvatella, A.

Color image enhancement based on perceptual sharpening

Color image enhancement based on perceptual sharpening


   TODO

de Queiroz, R.L.; Braun, K.M.

Color to gray and back: color embedding into textured gray images

Color to gray and back: color embedding into textured gray images


   TODO

Ali Alsam, Oyvind Kolas

Grey Colour Sharpening

Grey Colour Sharpening


   TODO

Drew, Mark S.; Connah, David; Finlayson, Graham D.; Bloj, Marina

Improved colour to greyscale via integrability correction

Paper


   TODO

Ali Alsam and Mark S. Drew

Fast Multispectral2Gray

Paper


   TODO

Zhang, Yi and Chen, Chun and Bu, Jiajun and Song, Mingli and Pang, Chen and Sun, Zhuo

A Kernel Based Algorithm for Fast Color-to-Gray Processing

Image and Signal Processing, 2008.


   TODO

Giovane R. Kuhn and Manuel M. Oliveira and Leandro A. F. Fernandes

An improved contrast enhancing approach for color-to-grayscale mappings

Paper


   TODO

Ming Cuiand Jiuxiang Hu and Anshuman Razdan and Peter Wonka

Color-to-gray conversion using ISOMAP

Paper


   TODO

Tae-Hee Lee, Byoung-Kwang Kim, Woo-Jin Song

Converting color images to grayscale images by reducing dimensions

Paper


   TODO

Luca Benedetti, Massimiliano Corsini, Paolo Cignoni, Marco Callieri, Roberto Scopigno

Color to gray conversions in the context of stereo matching algorithms




   TODO

Ye Zhao, Zakiya Tamimi

Spectral Image Decolorization




   TODO

D. Eynard, A. Kovnatsky, M. M. Bronstein

Laplacian colormaps: a framework for structure-preserving color transformations




   TODO

Chuong T. Nguyen, Joseph P. Havlicek

Color to grayscale image conversion using modulation domain quadratic programming

Paper


   TODO

Zhongping Ji, Mei-e Fang, Yigang Wang, Weiyin Ma

Efficient decolorization preserving dominant distinctions

Paper


   TODO

Zhengmeng Jin, Michael K. Ng

A contrast maximization method for color-to-grayscale conversion

Paper




PUBLICATIONS

Author Title Publishing details
Čadík, M. Perceptual Evaluation of Color-to-Grayscale Image Conversions Computer Graphics Forum (Proceedings of Pacific Graphics 08), Vol. 27, Issue 7, pp. 1745-1754, 2008.
Neumann, L., Čadík, M., Nemcics, A. An Efficient Perception-Based Adaptive Color to Gray Transformation Proceedings of CAe 2007, p.73 - p.80. Banff, Canada, 2007, ISSN 1816-0859.


RESOURCES

Perceptual Evaluation of Color-to-Grayscale Image Conversions
Perceptually-Plausible Conversion of Images to Grayscale