The Experts below are selected from a list of 54 Experts worldwide ranked by ideXlab platform
Dimitrios Androutsos - One of the best experts on this subject based on the ideXlab platform.
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color image watermarking using multidimensional fourier transforms
IEEE Transactions on Information Forensics and Security, 2008Co-Authors: Tsz Kin Tsui, Xiaoping Zhang, Dimitrios AndroutsosAbstract:This paper presents two vector watermarking schemes that are based on the use of complex and quaternion Fourier transforms and demonstrates, for the first time, how to embed watermarks into the frequency domain that is consistent with our human visual system. Watermark casting is performed by estimating the just-noticeable distortion of the images, to ensure watermark invisibility. The first method encodes the chromatic content of a color image into the CIE chromaticity coordinates while the achromatic content is encoded as CIE Tristimulus Value. Color watermarks (yellow and blue) are embedded in the frequency domain of the chromatic channels by using the spatiochromatic discrete Fourier transform. It first encodes and as complex Values, followed by a single discrete Fourier transform. The most interesting characteristic of the scheme is the possibility of performing watermarking in the frequency domain of chromatic components. The second method encodes the components of color images and watermarks are embedded as vectors in the frequency domain of the channels by using the quaternion Fourier transform. Robustness is achieved by embedding a watermark in the coefficient with positive frequency, which spreads it to all color components in the spatial domain and invisibility is satisfied by modifying the coefficient with negative frequency, such that the combined effects of the two are insensitive to human eyes. Experimental results demonstrate that the two proposed algorithms perform better than two existing algorithms - ac- and discrete cosine transform-based schemes.
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Color Image Watermarking using the Spatio-Chromatic Fourier Transform
2006Co-Authors: Tsz Kin Tsui, Xiaoping Zhang, Dimitrios AndroutsosAbstract:In this paper, a color watermarking algorithm is pro-posed. The method encodes the chromatic content of a color image as CIE a∗b ∗ chromaticity coordinates whereas the achromatic content is encoded as CIE L Tristimulus Value. Color watermarks (yellow and blue) are embedded in the frequency domain of the chromatic channels by using the Spatio Chromatic Discrete Fourier Transform (SCDFT). It first encodes a ∗ and b ∗ as complex Values, followed by a sin-gle discrete Fourier Transform. Watermark casting is per-formed by estimating the Just-Noticeable distortion (JND) of the images, to ensure watermark invisibility. The most interesting characteristics of the new scheme is the possibil-ity of performing watermarking in the frequency domain of chromatic components. 1
Tsz Kin Tsui - One of the best experts on this subject based on the ideXlab platform.
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color image watermarking using multidimensional fourier transforms
IEEE Transactions on Information Forensics and Security, 2008Co-Authors: Tsz Kin Tsui, Xiaoping Zhang, Dimitrios AndroutsosAbstract:This paper presents two vector watermarking schemes that are based on the use of complex and quaternion Fourier transforms and demonstrates, for the first time, how to embed watermarks into the frequency domain that is consistent with our human visual system. Watermark casting is performed by estimating the just-noticeable distortion of the images, to ensure watermark invisibility. The first method encodes the chromatic content of a color image into the CIE chromaticity coordinates while the achromatic content is encoded as CIE Tristimulus Value. Color watermarks (yellow and blue) are embedded in the frequency domain of the chromatic channels by using the spatiochromatic discrete Fourier transform. It first encodes and as complex Values, followed by a single discrete Fourier transform. The most interesting characteristic of the scheme is the possibility of performing watermarking in the frequency domain of chromatic components. The second method encodes the components of color images and watermarks are embedded as vectors in the frequency domain of the channels by using the quaternion Fourier transform. Robustness is achieved by embedding a watermark in the coefficient with positive frequency, which spreads it to all color components in the spatial domain and invisibility is satisfied by modifying the coefficient with negative frequency, such that the combined effects of the two are insensitive to human eyes. Experimental results demonstrate that the two proposed algorithms perform better than two existing algorithms - ac- and discrete cosine transform-based schemes.
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Color Image Watermarking using the Spatio-Chromatic Fourier Transform
2006Co-Authors: Tsz Kin Tsui, Xiaoping Zhang, Dimitrios AndroutsosAbstract:In this paper, a color watermarking algorithm is pro-posed. The method encodes the chromatic content of a color image as CIE a∗b ∗ chromaticity coordinates whereas the achromatic content is encoded as CIE L Tristimulus Value. Color watermarks (yellow and blue) are embedded in the frequency domain of the chromatic channels by using the Spatio Chromatic Discrete Fourier Transform (SCDFT). It first encodes a ∗ and b ∗ as complex Values, followed by a sin-gle discrete Fourier Transform. Watermark casting is per-formed by estimating the Just-Noticeable distortion (JND) of the images, to ensure watermark invisibility. The most interesting characteristics of the new scheme is the possibil-ity of performing watermarking in the frequency domain of chromatic components. 1
Xiaoping Zhang - One of the best experts on this subject based on the ideXlab platform.
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color image watermarking using multidimensional fourier transforms
IEEE Transactions on Information Forensics and Security, 2008Co-Authors: Tsz Kin Tsui, Xiaoping Zhang, Dimitrios AndroutsosAbstract:This paper presents two vector watermarking schemes that are based on the use of complex and quaternion Fourier transforms and demonstrates, for the first time, how to embed watermarks into the frequency domain that is consistent with our human visual system. Watermark casting is performed by estimating the just-noticeable distortion of the images, to ensure watermark invisibility. The first method encodes the chromatic content of a color image into the CIE chromaticity coordinates while the achromatic content is encoded as CIE Tristimulus Value. Color watermarks (yellow and blue) are embedded in the frequency domain of the chromatic channels by using the spatiochromatic discrete Fourier transform. It first encodes and as complex Values, followed by a single discrete Fourier transform. The most interesting characteristic of the scheme is the possibility of performing watermarking in the frequency domain of chromatic components. The second method encodes the components of color images and watermarks are embedded as vectors in the frequency domain of the channels by using the quaternion Fourier transform. Robustness is achieved by embedding a watermark in the coefficient with positive frequency, which spreads it to all color components in the spatial domain and invisibility is satisfied by modifying the coefficient with negative frequency, such that the combined effects of the two are insensitive to human eyes. Experimental results demonstrate that the two proposed algorithms perform better than two existing algorithms - ac- and discrete cosine transform-based schemes.
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Color Image Watermarking using the Spatio-Chromatic Fourier Transform
2006Co-Authors: Tsz Kin Tsui, Xiaoping Zhang, Dimitrios AndroutsosAbstract:In this paper, a color watermarking algorithm is pro-posed. The method encodes the chromatic content of a color image as CIE a∗b ∗ chromaticity coordinates whereas the achromatic content is encoded as CIE L Tristimulus Value. Color watermarks (yellow and blue) are embedded in the frequency domain of the chromatic channels by using the Spatio Chromatic Discrete Fourier Transform (SCDFT). It first encodes a ∗ and b ∗ as complex Values, followed by a sin-gle discrete Fourier Transform. Watermark casting is per-formed by estimating the Just-Noticeable distortion (JND) of the images, to ensure watermark invisibility. The most interesting characteristics of the new scheme is the possibil-ity of performing watermarking in the frequency domain of chromatic components. 1
S K Mitra - One of the best experts on this subject based on the ideXlab platform.
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a new class of chromatic filters for color image processing theory and applications
IEEE Transactions on Image Processing, 2004Co-Authors: L. Lucchese, S K MitraAbstract:This paper advances a new framework for chromatic filtering of color images. The chromatic content of a color image is encoded in the CIE u'v' chromaticity coordinates whereas the achromatic content is encoded as CIE Y Tristimulus Value. Within the u'v' chromaticity diagram, colors are added according to the well-known center of gravity law of additive color mixtures, which is generalized here into a nonlinear filtering scheme for processing the two chromatic signals u' and v'. The achromatic channel Y can be processed with traditional filtering schemes, either linear or nonlinear, depending on the specific task at hand. The most interesting characteristics of the new filtering scheme are: 1) the elimination of color smearing effects along edges between bright and dark areas; 2) the possibility of processing chromatic components in a noniterative fashion through linear convolution operations; and 3) the consequent amenability to computationally efficient implementations with fast Fourier transform. The paper includes several examples with both synthetic and real images where the performance of the new filtering method is compared with that of other color image processing algorithms.
Nagaaki Ohyama - One of the best experts on this subject based on the ideXlab platform.
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color image reproduction based on multispectral and multiprimary imaging experimental evaluation
electronic imaging, 2001Co-Authors: Masahiro Yamaguchi, Yuri Murakami, Hideto Motomura, Kenro Ohsawa, Taishi Teraji, Toshio Uchiyama, Nagaaki OhyamaAbstract:Multispectral imaging is significant technology for the acquisition and display of accurate color information. Natural color reproduction under arbitrary illumination becomes possible using spectral information of both image and illumination light. In addition, multiprimary color display, i.e., using more than three primary colors, has been also developed for the reproduction of expanded color gamut, and for discounting observer metamerism. In this paper, we present the concept for the multispectral data interchange for natural color reproduction, and the experimental results using 16-band multispectral camera and 6-primary color display. In the experiment, the accuracy of color reproduction is evaluated in CIE (Delta) Ea*b* for both image capture and display systems. The average and maximum (Delta) Ea*b* = 1.0 and 2.1 in 16-band mutispectral camera system, using Macbeth 24 color patches. In the six-primary color projection display, average and maximum (Delta) Ea*b* = 1.3 and 2.7 with 30 test colors inside the display gamut. Moreover, the color reproduction results with different spectral distributions but same CIE Tristimulus Value are visually compared, and it is confirmed that the 6-primary display gives improved agreement between the original and reproduced colors.
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Color Image Reproduction Based on the Multispectral and Multiprimary Imaging: Experimental Evaluation
2001Co-Authors: Masahiro Yamaguchi, Yuri Murakami, Hideto Motomura, Kenro Ohsawa, Taishi Teraji, Toshio Uchiyama, Nagaaki OhyamaAbstract:Multispectral imaging is significant technology for the acquisition and display of accurate color information. Natural color reproduction under arbitrary illumination becomes possible using spectral information of both image and illumination light. In addition, multiprimary color display, i.e., using more than three primary colors, has been also developed for the reproduction of expanded color gamut, and for discounting observer metamerism. In this paper, we present the concept for the multispectral data interchange for natural color reproduction, and the experimental results using 16-band multispectral camera and 6-primary color display. In the experiment, the accuracy of color reproduction is evaluated in CIE ∆Ea*b * for both image capture and display systems. The average and maximum ∆Ea*b * = 1.0 and 2.1 in 16-band mutispectral camera system, using Macbeth 24 color patches. In the six-primary color projection display, average and maximum ∆Ea*b * = 1.3 and 2.7 with 30 test colors inside the display gamut. Moreover, the color reproduction results with different spectral distributions but same CIE Tristimulus Value are visually compared, and it is confirmed that the 6-primary display gives improved agreement between the original and reproduced colors
