Topic
Alpha compositing
About: Alpha compositing is a research topic. Over the lifetime, 482 publications have been published within this topic receiving 11035 citations. The topic is also known as: alpha blend & alpha channel.
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01 Jan 2015
TL;DR: A visionless authentication method based on secret sharing technique with additional data repairing ability for the gray-scale document images by using Portable Network Graphics (PNG) is presented and can survive malicious attacks of common content modification.
Abstract: A visionless authentication method is based on secret sharing technique with additional data repairing ability for the gray-scale document images by using Portable Network Graphics (PNG) is presented. For each data block of gray-scale document images authentication signal is produced then this produced authentication signal and binarized data block content is transmute by using the secret Shamir scheme ,the contributed values are selected such that as many shares can produced and place in to the alpha channel plane. To create PNG image the alpha channel plane is added with the gray-scale document image at the time of placing the values, computed shares are correlated to the range of alpha channel values extent up to 255 to get the stego-image. An image block is patent as damaged if the authentication signal calculated from the present block that does not matches which is calculated from the placed values of alpha channel plane. The reverse Shamir scheme is applied to repair the damaged data block content by collecting two shares from unobtrusive data block. The proposed method can survive malicious attacks of common content modification, such as super imposition, painting etc.
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09 Dec 2008TL;DR: Simulation results show that MMMTC can provide better image quality with similar memory bandwidth for RGB channels and outperform other texture compression systems for alpha channel and hardware cost is similar to that of DXTC and is suitable to be integrated in GPU to provide high-quality textures with low memory bandwidth requirement.
Abstract: This paper presents a high-quality multi-mode mipmapping texture compression with alpha map (MMMTC) system. Based on wavelet transform, a hierarchical approach is adopted for mipmap in YCbCr color space to embed three levels of mipmap in a single bitstream. In addition, by inspecting the similarity between alpha channel and luminance channel, the alpha high coefficients are efficiently encoded with linear prediction from the luminance high coefficients in three modes. Simulation results show that MMMTC can provide better image quality with similar memory bandwidth for RGB channels and outperform other texture compression systems for alpha channel. VLSI implementation result shows that the hardware cost of MMMTC is similar to that of DXTC and is suitable to be integrated in GPU to provide high-quality textures with low memory bandwidth requirement.
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03 Dec 2013TL;DR: A novel approach called Uniform Sample Compositing (USC) is presented to improve the efficiency of gradient-domain compositing of large image, which could be implemented in significantly reduced time and memory.
Abstract: We present a novel approach called Uniform Sample Compositing (USC) to improve the efficiency of gradient-domain compositing of large image, which could be implemented in significantly reduced time and memory. Firstly, our algorithm divides an original source image into many quadrilateral patches, and discards inner pixels and reserves the border pixels of patches) to constitute two low resolution images (Uniform-Sample-images) on which the image compositing operator is implemented. Finally according to the solution of Uniform-Sample-images the result image is evaluated by concurrently computing inner pixels of every quadrilateral patch on GPU. The evaluation of these patches is independent to each other so that our algorithm has better parallelism. The reduction of time and memory is achieved by solving Poisson equation on low resolution and inner interpolation on quadrilateral patches. The major merits of our approach are demonstrated by performing large image composite (whose size is about multi-Gigabyte) in significantly reduced time and memory while achieving visually identical results.
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TL;DR: The method of image authentication, tampering detection and repairing of the tampered data is explained and the result is provided only for grayscale images and supposed to expand for color images as well.
Abstract: It is very crucial to design efficient methods to provide authentication to document images mainly for images whose security must be protected. In digital media the authentication, tampering detection and repairing of the tampered data is main concern. Nowadays many digital documents are transferred on the internet regularly e.g. circuit diagrams, scanned cheques, signed documents, drawings, design drafts etc. Here the method of image authentication, tampering detection and repairing is explained. The grayscale image document image authentication with self repair method is provided. The authentication signal is calculated from binary image of the original document image. Secret sharing scheme is used to calculate this authentication signal. The extra alpha channel is embedded in the original grayscale document image. The calculated authentication signal is then embedded in this alpha channel. This is one of the way of visual cryptography in which image is visible but authentication signal will not be recognized. Then this authentic image is encrypted for better security. this whole procedure is done at sender side. In second module i.e. receiver side the image is decrypted. Then the embedded authentication signal is extracted from the received authentic image. The new authentication signal is calculated from the binary image of the received authentic image. This new authentication signal is compared with the extracted signal and the integrity check is provided. If data modification is detected, then the method is proved to repair the tampered pixels using the reverse secret sharing method. The tampering of data is detected successfully in this method without any original image backup. This type of secret sharing scheme is helpful for reducing the risk of incidental partial data loss. This method is also applicable to the color image. Algorithm for color image is also same as grayscale images. In this paper the result is provided only for the grayscale images and supposed to expand for color images as well.
01 Jun 2015
TL;DR: The proposed algorithm use principal component analysis (PCA) and k-nearest neighborhood (k-NN) to determine the location of input images before performing a template-based matching and synthesize input images by alpha blending to improve the computational efficiency.
Abstract: Image stitching method is a technique for obtaining an high-resolution image by combining two or more images. In X-ray image for clinical diagnosis, the size of the imaging region taken by one shot is limited due to the field-of-view of the equipment. Therefore, in order to obtain a high-resolution image including large regions such as a whole body, the synthesis of multiple X-ray images is required. In this paper, we propose a rapid stitching method of digital X-ray images using template-based registration. The proposed algorithm use principal component analysis(PCA) and k-nearest neighborhood(k-NN) to determine the location of input images before performing a template-based matching. After detecting the overlapping position using template-based matching, we synthesize input images by alpha blending. To improve the computational efficiency, reduced images are used for PCA and k-NN analysis. Experimental results showed that our method was more accurate comparing with the previous method with the improvement of the registration speed. Our stitching method could be usefully applied into the stitching of 2D or 3D multiple images.