Topic
Channel (digital image)
About: Channel (digital image) is a research topic. Over the lifetime, 7211 publications have been published within this topic receiving 69974 citations.
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TL;DR: The experimental results show that the proposed approach provides extra imperceptibility, security and robustness against JPEG compression and different noise attacks compared to the similar proposed methods in earlier works.
Abstract: The most digital image watermarking algorithms have nearly always been realised in red, green and blue (RGB) colour space. In this study, a secure, robust and imperceptible CDMA image watermarking scheme which uses discrete wavelet transform is proposed and tested in eight colour spaces RGB, YCbCr, JPEG-YCbCr, YIQ, YUV, hue, saturation, intensity, hue, saturation, value and CIELab to determine which colour space is more effective in watermarking algorithms based on correlation techniques and provides a result which does not differ immeasurably from the original with respect to imperceptibility and robustness. In the proposed scheme, a scrambled binary image by Arnold transform map, after encryption, is embedded into sub-images of the first channel wavelet decomposition of intended colour space using block processing technique. The experimental results show that the proposed approach provides extra imperceptibility, security and robustness against JPEG compression and different noise attacks compared to the similar proposed methods in earlier works.
48 citations
TL;DR: Examining windowed pulse rates, there is little observable difference in mean absolute error or error distributions resulting from reduced frame rates or image resolution, thus lowering requirements for systems measuring pulse rate over sufficient length time windows.
Abstract: Non-contact, imaging photoplethysmography uses cameras to facilitate measurements including pulse rate, pulse rate variability, respiration rate, and blood perfusion by measuring characteristic changes in light absorption at the skin’s surface resulting from changes in blood volume in the superficial microvasculature. Several factors may affect the accuracy of the physiological measurement including imager frame rate, resolution, compression, lighting conditions, image background, participant skin tone, and participant motion. Before this method can gain wider use outside basic research settings, its constraints and capabilities must be well understood. Recently, we presented a novel approach utilizing a synchronized, nine-camera, semicircular array backed by measurement of an electrocardiogram and fingertip reflectance photoplethysmogram. Twenty-five individuals participated in six, five-minute, controlled head motion artifact trials in front of a black and dynamic color backdrop. Increasing the input channel space for blind source separation using the camera array was effective in mitigating error from head motion artifact. Herein we present the effects of lower frame rates at 60 and 30 (reduced from 120) frames per second and reduced image resolution at 329x246 pixels (one-quarter of the original 658x492 pixel resolution) using bilinear and zero-order downsampling. This is the first time these factors have been examined for a multiple imager array and align well with previous findings utilizing a single imager. Examining windowed pulse rates, there is little observable difference in mean absolute error or error distributions resulting from reduced frame rates or image resolution, thus lowering requirements for systems measuring pulse rate over sufficient length time windows.
48 citations
TL;DR: A fragile technique that can detect the most minor changes in a marked image using a DCT-based data hiding method to embed a tamper-detection mark and a semi-fragile technique that detects the locations of significant manipulations while disregarding the less important effects of image compression and additive channel noise.
Abstract: In this paper, we present two tamper-detection techniques. The first is a fragile technique that can detect the most minor changes in a marked image using a DCT-based data hiding method to embed a tamper-detection mark. The second is a semi-fragile technique that detects the locations of significant manipulations while disregarding the less important effects of image compression and additive channel noise. Both techniques are fully described and the performance of each algorithms demonstrated by manipulation of the marked images.
48 citations
TL;DR: A novel way of confusion is designed by introducing intra-permutation and Exclusive-OR operation with complementary DNA rules that brings randomness in the image to achieve high quality of encryption results.
Abstract: In the proposed article, a novel way of confusion is designed by introducing intra-permutation and Exclusive-OR operation with complementary DNA rules that brings randomness in the image. A SHA-256 hash function is used for modification of the initial conditions for 2-Dimensional Logistic map. In the 1st phase of diffusion, the rows of the three colored channels are exchanged by selecting DC-Boxes chaotically and then same operation is applied on the columns. In 2nd diffusion phase, each color channel is permuted independently using chaotic sequence. Before confusion, DNA encoding is applied at pixel level chaotically and transformed each color channel into a linear array. These three arrays are combined into a matrix of three rows and multiple columns. This matrix is divided into blocks; each of size of three DNA bases; one from each color channel and substituted by Intra-channel diffusion using DC-Boxes. In 2nd phase of confusion, matrix is transformed into a large 1D array representing DNA bases of a color image. This large array is split into groups of size of four DNA bases; representing a pixel. These groups are substituted by Exclusive-OR operation with DNA complementary rules that selected chaotically. The proposed algorithm requires only single round of confusion/diffusion operation to achieve high quality of encryption results. This scheme is quite different for color image encryption based on DNA and has better results for different tests like NPCR, UACI, information entropy etc. Besides the larger key space, resistance against common transmission noise is another significant advantage of proposed scheme over some existing systems.
47 citations
19 Nov 2013
TL;DR: By considering multi-scale contrast preservation, this work designs an algorithm that can consistently produce "good" results for each color image, among which the "best" one preferred by users can be selected by further involving perceptual contrasts preferences.
Abstract: Decolorization problems originate from the fact that the luminance channel may fail to represent iso-luminant regions in the original color image. Currently all the existing methods suffer from the same weakness -- robustness: failure cases can be easily found for each of the methods. This prevents all these methods from being practical for real-world applications. In fact, the luminance conversion (i.e, rgb2gray() function in Matlab) performs rather well in practice only with exceptions for failure cases like the iso-luminant regions. Thus a thought-provoking question is naturally raised: can we reach a robust solution by simply modifying the rgb2gray() to avoid failures in iso-luminant regions? Instead of assigning fixed channel weights for all images, a more flexible strategy would be choosing channel weights depending on specific images to avoid indiscrimination in iso-luminant regions. Following this strategy, by considering multi-scale contrast preservation, we design an algorithm that can consistently produce "good" results for each color image, among which the "best" one preferred by users can be selected by further involving perceptual contrasts preferences. The results are verified through user study.
47 citations