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Quantization (image processing)

About: Quantization (image processing) is a research topic. Over the lifetime, 7977 publications have been published within this topic receiving 126632 citations.


Papers
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Patent
30 Jun 2000
TL;DR: In this paper, the authors proposed to remove high-frequency AC DCT coefficients at the end of the coefficient scan order to reduce the frequency of escape sequences in the (run, level) coding.
Abstract: To reduce bandwidth of non-scalable MPEG-2 coded video, certain non-zero AC DCT coefficients for the 8×8 blocks are removed from the MPEG-2 coded video. In one implementation, high-frequency AC DCT coefficients are removed at the end of the coefficient scan order. This method requires the least computation and is most desirable if the reduced-bandwidth video is to be spatially sub-sampled. In another implementation, the smallest-magnitude AC DCT coefficients are removed. This method may produce an undesirable increase in the frequency of occurrence of escape sequences in the (run, level) coding. This frequency can be reduced by retaining certain non-zero AC DCT coefficients that are not the largest magnitude coefficients, and by increasing a quantization scale to reduce the coefficient levels. The reduced-bandwidth video can be used for a variety of applications, such as browsing for search and play-list generation, bit stream scaling for splicing, and bit-rate adjustment for services with limited resources and for multiplexing of transport streams.

100 citations

Journal ArticleDOI
TL;DR: This paper explains how quantization tables work, how they can be used for image source identification, and the implications for computer forensics.

100 citations

Patent
21 Feb 2009
TL;DR: In this article, a system and method for encoding multimedia video is described, where the quantization parameter for each macroblock may be selected by limiting the universe of all possible quantization parameters to a particular range of possible quantisation parameter values.
Abstract: A system and method for encoding multimedia video is described. As video is encoded a quantization parameter is selected for each macroblock. As described herein, the quantization parameter for each macroblock may be selected by limiting the universe of all possible quantization parameters to a particular range of possible quantization parameter values. This increases the speed of video encoding by reducing the number of quantization parameters that are tested for each video macroblock.

98 citations

Journal ArticleDOI
01 Dec 2013-Optik
TL;DR: Experimental results show that the proposed novel blind watermarking algorithm not only can resist both traditional signal processing attacks and geometric attacks, but also has more efficient in computational complexity.

98 citations

Journal ArticleDOI
TL;DR: The experimental results demonstrate that the proposed DCT based quantization and Discrete Cosine Transform based self-embedding fragile watermarking scheme not only outperforms high quality restoration effectively, but also removes the blocking artifacts and improves the accuracy of tamper localization due to use of very small size blocks.
Abstract: Due to rapid development of Internet and computer technology, image authentication and restoration are very essential, especially when it is utilized in forensic science, medical imaging and evidence of court. A quantization and Discrete Cosine Transform(DCT) based self-embedding fragile watermarking scheme with effective image authentication and restoration quality is proposed in this paper. In this scheme, the cover image is divided in size of 2×2 non-overlapping blocks. For each block twelve bits watermark are generated from the five most significant bits (MSBs) of each pixel and are embedded into the three least significant bits (LSBs) of the pixels corresponding to the mapped block. The proposed scheme uses two levels encoding for content restoration bits generation. The restoration is achievable with high PSNR and NCC up to 50 % tampering rate. The experimental results demonstrate that the proposed scheme not only outperforms high quality restoration effectively, but also removes the blocking artifacts and improves the accuracy of tamper localization due to use of very small size blocks.

97 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20228
2021354
2020283
2019294
2018259
2017295