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

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
		Xiuyu Zheng, Jie Feng, Bingfeng Zhou Efficient Color-to-Gray Conversion for Digital Images in Gradient Domain
		Zhongping Ji, Mei-e Fang, Yigang Wang, Weiyin Ma Efficient decolorization preserving dominant distinctions Paper
		Jiaojiao Xiong, Hongyang Lu, Qiegen Liu, Xiaoling Xu Parametric ratio-based method for efficient contrast-preserving decolorization
		Bin Jin and Sabine Susstrunk Preserving Perceptual Contrast in Decolorization with Optimized Color Orders
		Ali Alsam, Oyvind Kolas Grey Colour Sharpening Grey Colour Sharpening
		Tirui Wu, Ciaran Eising, Martin Glavin, Edward Jones An Efficient and Effective Image Decolorization Algorithm Based on Cumulative Distribution Function
		Qiegen Liu, Peter X. Liu, Weisi Xie, Yuhao Wang, Dong Liang GcsDecolor: Gradient Correlation Similarity for Efficient Contrast Preserving Decolorization
		Qiegen Liu, Peter Xiaoping Liu, Yuhao Wang, Henry Leung Semiparametric Decolorization With Laplacian-Based Perceptual Quality Metric
		Qiegen Liu, Guangpu Shao, Yuhao Wang, Junbin Gao, and Henry Leung Log-Euclidean Metrics for Contrast Preserving Decolorization
		Hossein Ziaei Nafchi, Atena Shahkolaei, Rachid Hedjam, Mohamed Cheriet CorrC2G: Color to Gray Conversion by Correlation
		Ali Alsam Opponent Center-Surround Contrast: Colour to Grey Conversion
		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
		Lina Zhang, Yi Wan Color-to-gray image conversion using salient colors and radial basis functions

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	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 Colour2Grey, 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	Zhengmeng Jin, Michael K. Ng A contrast maximization method for color-to-grayscale conversion Paper
	TODO	Cewu Lu, Li Xu, Jiaya Jia Contrast Preserving Decolorization with Perception-Based Quality Metrics
	TODO	Jung Gap Kuk, Jae Hyun Ahn, Nam Ik Cho A Color to Grayscale Conversion Considering Local and Global Contrast
	TODO	Wei Zhu, Ruizhen Hu, Ligang Liu Grey Conversion via Perceived-contrast
	TODO	Rodrigo Palma-Amestoy, Edoardo Provenzi, Marcelo Bertalmio, Vincent Caselles A Perceptually Inspired Variational Framework for Color Enhancement
	TODO	Cheryl Lau, Wolfgang Heidrich, Rafal Mantiuk Cluster-Based Color Space Optimizations
	TODO	Shaodi You, Nick Barnes, Janine Walker Perceptually Consistent Color-to-Gray Image Conversion
	TODO	Ranbeer Tyagi, Geetam Singh Tomar Transformation of Image from Color to Gray Scale Using Contrast among DPCM and LMS Method
	TODO	Jie Chen, Xin Li, Xiuchang Zhu, Jin Wang Visual Perception Preserving Decolorization Method
	TODO	Qiegen Liu, Jiaojiao Xiong, Li Zhu, Minghui Zhang, Yuhao Wang Extended RGB2Gray conversion model for efficient contrast preserving decolorization
	TODO	Hong-yang LU, Qie-gen LIU,Yu-hao WANG, Xiao-hua DENG A two-stage parametric subspace model for efficient contrast-preserving decolorization
	TODO	Wei Hu, Wei Li, Fan Zhang, Qian Du Real-time Decolorization using Dominant Colors
	TODO	Hao Du, Shengfeng He, Bin Sheng, Lizhuang Ma, Rynson W. H. Lau Saliency-Guided Color-to-Gray Conversion Using Region-Based Optimization
	TODO	Mingli Song, Dacheng Tao, Chun Chen, Xuelong Li, Chang Wen Chen Color to Gray: Visual Cue Preservation
	TODO	Qiegen Liu, Peter Xiaoping Liu, Yuhao Wang, Henry Leung Semiparametric Decolorization With Laplacian-Based Perceptual Quality Metric
	TODO	Qiegen Liu, Sanqian Li, Jiaojiao Xiong, Binjie Qin WpmDecolor: weighted projection maximum solver for contrast-preserving decolorization
	TODO	Soo-Chang Pei, Wang-Lin Su, Chiou-Shann Fuh Local and Global Contrast Preserving Decolorization using Gradient Matrix Correlation
	TODO	Yizhang Tao, Yiyi Shen, Bin Sheng, Ping Li, and Rynson W. H. Lau Video Decolorization Using Visual Proximity Coherence Optimization
	TODO	Chengho Hsin, Hoai-Nam Le, Shaw-Jyh Shin Color to Grayscale Transform Preserving Natural Order of Hues
	TODO	Hanli Zhao, Haining Zhang, Xiaogang Jin Efficient image decolorization with a multimodal contrast-preserving measure
	TODO	Xudong Kang and Puhong Duan and Shutao Li and Jón Atli Benediktsson Decolorization-Based Hyperspectral Image Visualization
	TODO	Xiaoli Zhang and Shiguang Liu Contrast preserving image decolorization combining global features and local semantic features
	TODO	Jun Liu, Faming Fang, Ning Du Color-to-gray conversion with perceptual preservation and dark channel prior
	TODO	Shiguang Liu, Xiaoli Zhang Image Decolorization combining Local Features and Exposure Features
	TODO	Qiegen Liu, Henry Leung Variable augmented neural network for decolorization and multi-exposure fusion
	TODO	Menghan Xia, Xueting Liu, Tien-Tsin Wong Invertible Grayscale
	TODO	He Chen, Faming Fang Bregman-Tanimoto Based Method for Contrast Preserving Decolorization
	TODO	Cosmin Ancuti, Codruta O. Ancuti, Miquel Feixas, Mateu Sbert Image Decolorization Based on Information Theory
	TODO	Orhan Akbulut A new perspective on decolorization: feature-preserving decolorization
	TODO	Yong Du, Yangyang Xu, Taizhong Ye, Qiang Wen, Chufeng Xiao, Junyu Dong, Guoqiang Han, Shengfeng He Invertible Grayscale with Sparsity Enforcing Priors
	TODO	Shiguang Liu, Huixin Wang, Xiaoli Zhang Video Decolorization Based on the CNN and LSTM Neural Network
	TODO	Jing Yu, Fang Li, Xiaoguang Lv Contrast preserving decolorization based on the weighted normalized L1 norm
	TODO	Ayça Ceylan, ve Burcu Tunga, Evrim Korkmaz özay Color to Grayscale Image Conversion Using High Dimensional Model Representation
	TODO	Kunlin Liu, Dongdong Chen, Jing Liao, Weiming Zhang, Hang Zhou, Jie Zhang, Wenbo Zhou, Nenghai Yu JPEG Robust Invertible Grayscale
	TODO	Prasoon Ambalathankandy, Yafei Ou, Masayuki Ikebe Warm-cool color-based high-speed decolorization: an empirical approach for tone mapping applications

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

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:

COLOR-TO-GRAYSCALE IMAGE CONVERSION

IMPLEMENTED CONVERSIONS

CIE Y channel

Raja Bala, Reiner Eschbach

Spatial Color-to-Grayscale Transform Preserving Chrominance Edge Information

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

Color2Gray: Salience-Preserving Color Removal

K. Rasche, R. Geist, J. Westall

Re-coloring Images for Gamuts of Lower Dimension

Mark Grundland, Neil A. Dodgson

Decolorize: Fast, Contrast Enhancing, Color to Grayscale Conversion

Laszlo Neumann, Martin Cadik, Antal Nemcsics

An Efficient Perception-Based Adaptive Color to Gray Transformation

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

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

Zhinan Xu, Julien Demouth, Seungyong Lee

Optimization-based Image Decolorization

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

Two-scale Tone Management for Photographic Look

Cosmin Ancuti, Codruta O. Ancuti

Laplacian-guided image decolorization

Xiuyu Zheng, Jie Feng, Bingfeng Zhou

Efficient Color-to-Gray Conversion for Digital Images in Gradient Domain

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

Efficient decolorization preserving dominant distinctions

Jiaojiao Xiong, Hongyang Lu, Qiegen Liu, Xiaoling Xu

Parametric ratio-based method for efficient contrast-preserving decolorization

Bin Jin and Sabine Susstrunk

Preserving Perceptual Contrast in Decolorization with Optimized Color Orders

Ali Alsam, Oyvind Kolas

Grey Colour Sharpening

Tirui Wu, Ciaran Eising, Martin Glavin, Edward Jones

An Efficient and Effective Image Decolorization Algorithm Based on Cumulative Distribution Function

Qiegen Liu, Peter X. Liu, Weisi Xie, Yuhao Wang, Dong Liang

GcsDecolor: Gradient Correlation Similarity for Efficient Contrast Preserving Decolorization

Qiegen Liu, Peter Xiaoping Liu, Yuhao Wang, Henry Leung

Semiparametric Decolorization With Laplacian-Based Perceptual Quality Metric

Qiegen Liu, Guangpu Shao, Yuhao Wang, Junbin Gao, and Henry Leung

Log-Euclidean Metrics for Contrast Preserving Decolorization

Hossein Ziaei Nafchi, Atena Shahkolaei, Rachid Hedjam, Mohamed Cheriet

CorrC2G: Color to Gray Conversion by Correlation

Ali Alsam

Opponent Center-Surround Contrast: Colour to Grey Conversion

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

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

Lina Zhang, Yi Wan

Color-to-gray image conversion using salient colors and radial basis functions

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

David Hafner and Joachim Weickert

Variational Image Fusion with Optimal Local Contrast

Raja Bala, Karen M. Braun

Color-to-Grayscale Conversion to Maintain Discriminability

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

Color image enhancement based on perceptual sharpening

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

Improved colour to greyscale via integrability correction

Ali Alsam and Mark S. Drew

Fast Colour2Grey, Fast Multispectral2Gray

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

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

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

Ming Cuiand Jiuxiang Hu and Anshuman Razdan and Peter Wonka

Color-to-gray conversion using ISOMAP

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

Converting color images to grayscale images by reducing dimensions

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

Color to gray conversions in the context of stereo matching algorithms

Ye Zhao, Zakiya Tamimi

Spectral Image Decolorization

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

Laplacian colormaps: a framework for structure-preserving color transformations

Chuong T. Nguyen, Joseph P. Havlicek

Color to grayscale image conversion using modulation domain quadratic programming