We propose a class of scalable video compression algorithms, within which compression performance may be exchanged for end-to-end delay. Each of the algorithms in this class produces a highly scalable bit stream, from...
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We propose a class of scalable video compression algorithms, within which compression performance may be exchanged for end-to-end delay. Each of the algorithms in this class produces a highly scalable bit stream, from which subsets may be extracted for compatibility with a wide range of display frame sizes, frame rates and bit rate constraints. Moreover, with modest end-to-end delay, the reconstructed video quality associated with any of these subsets is often superior to that obtained using an implementation of the inherently non-scalable MPEG-1 compression standard, operated with equivalent resolution and bit rate constraints. We describe scalable compressed data structures based on a layered substream abstraction, with simple, generic scaling operations, for both constant bit rate and constant distortion scaling criteria.< >
Vector quantization systems are usually based on digital implementation of the core operations. In this paper, video compression systems exploiting an analog implementation of vector quantization are presented. The ma...
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Vector quantization systems are usually based on digital implementation of the core operations. In this paper, video compression systems exploiting an analog implementation of vector quantization are presented. The main advantages of analog design are exploited, obtaining notable performances when compared to other solutions found in the literature. The circuit features a very modular, completely parallel internal architecture. Many circuits can be easily connected to obtain a larger codebook size and a larger vector dimension. Synthesis of codebooks is also described.
We consider the use of perceptual image quality assessment for quantization table (QT) optimization for JPEG compression. For evaluating performance, we consider the use of the Structural Similarity Index (SSIM) for e...
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We consider the use of perceptual image quality assessment for quantization table (QT) optimization for JPEG compression. For evaluating performance, we consider the use of the Structural Similarity Index (SSIM) for evaluating distortion in the compressed images. This leads to the study of rate-SSIM curves that replace the traditional use of rate-distortion curves based on the *** introduce a multi-objective optimization framework for estimating the best rate-SSIM curves. To estimate globally optimal quantization tables, A stochastic-optimization algorithm based on Simulated Annealing is proposed and its variations are studied. We report results on all methods on the Lena image and results from selected methods on the LIVE image quality assessment database. For the LIVE database, compared to the use of the standard JPEG quantization table at quality factor QF=95, QTs based on the training set give average bitrate reductions of 11.68%, 7.7% and an increase of 2.4%, while the SSIM quality changes from -0.11%,+0.05% and 0.12% respectively. In all cases, the results indicate that all considered methods improved over the use of standard JPEG tables.
Two VQ-based image-tamper-proofing schemes for digital grayscale images are presented in this paper. The first scheme, which we call Scheme-1, partitions a VQ codebook into two sub-codebooks called the sub-codebook 0 ...
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Two VQ-based image-tamper-proofing schemes for digital grayscale images are presented in this paper. The first scheme, which we call Scheme-1, partitions a VQ codebook into two sub-codebooks called the sub-codebook 0 and the sub-codebook 1. The sub-codebook 0 is used to imply embed authentication bit 0, and sub-codebook 1 is used to imply authentication bit 1. Once an intruder has modified the signed image, our Scheme-1 has the ability to detect the locations of the modified places according to the embedded authentication codes. One of the advantages of Scheme-1 is that it can tolerate reasonable image processing such as JPEG compression and the like. On the other hand, in order to enhance the image quality of Scheme-1, the concept of multiple codebooks is added in Scheme-2. Both of the schemes require no presence of the original image when they perform the verification procedure. Experimental results show that the image quality of Scheme-1 and Scheme-2 is acceptable without producing noticeable distortion. Besides, our analyses will also show that the robustness and the security of Scheme-1 and Scheme-2 are quite established.
This paper proposes an improved histogram-based approach to identifying whether an image is never compressed or has undergone JPEG compression with quality factor 100. The key idea is that the image's DCT (Discret...
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This paper proposes an improved histogram-based approach to identifying whether an image is never compressed or has undergone JPEG compression with quality factor 100. The key idea is that the image's DCT (Discrete Cosine transform) coefficients follow either of two families of parametric distributions, corresponding respectively to never compressed images and JPEG-100 compressed ones. This paper highlights that choosing the generalized Gaussian distribution (GGD) to model the DCT coefficients and constructing a DCT histogram with precision higher than integer create a prominent distinction between the DCT coefficients distribution of the two kinds of images. Experiments demonstrate that the proposed approach significantly outperforms existing histogram-based methods for the task of JPEG-100 forensics.
This paper describes a spatially variant method that optimises the compression rate within a given image dynamically depending on the application specific requirements and the actual image content. The concept utilise...
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ISBN:
(纸本)0780381858
This paper describes a spatially variant method that optimises the compression rate within a given image dynamically depending on the application specific requirements and the actual image content. The concept utilises the JPEG2000 standard, however, a generalised region-of-interest (ROI) map is used in this paper together with a different post-compression rate distortion optimisation. The generalised ROI map comprises a multi-level priority scheme as well as continuously adjustable qualities for each individual region to reflect the application specific requirements for a particular image. The key point is that these pre-defined quality constraints are always met for each individual region, thus making the approach suitable for data with inherent reliability requirements. The implementation of the proposed system is transparent and concerns only the encoder side while any standard JPEG2000 decoder can be used for decompression. Results have shown that for the utilised imagery, i.e. satellite and medical images, compression rate improvements of up to 32% in comparison to the JPEG2000 compressor fulfilling the same quality needs are achievable.
Assessing quality of distorted/decompressed images without reference to the original image is difficult due to vagueness in extracted features and complex relation between features and visual quality of images. The pa...
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Assessing quality of distorted/decompressed images without reference to the original image is difficult due to vagueness in extracted features and complex relation between features and visual quality of images. The paper aims at assessing the quality of distorted/decompressed images without any reference to the original image by developing an adaptive network based fuzzy inference system (ANFIS). First level Haar approximation entropies of test images from LIVE database and region based features extracted from the benchmark images are considered as inputs while mean opinion score (MOS) based quality of the images used as output to the fuzzy inference system (FIS). The input-output variables of the FIS are expressed using linguistic variables and fuzzified to measure the vagueness in extracted features. Takagi-Sugeno-Kang (TSK) inference rule has been applied to the FIS to predict the quality of a new distorted/decompressed image. The FIS has been trained to tune the parameters of the membership functions of the fuzzy sets that assess quality of the image more accurately. Quality of decompressed and various noise incorporated distorted test images are predicted using the proposed method producing output comparable with other existing no reference techniques. Results are validated with the objective and subjective image quality measures.
In this paper we address the problem of robustly embedding 64 bits into an image while taking into account the H VS. The proposed method is general in that any mask can be adopted. The main advantage of the framework ...
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In this paper we address the problem of robustly embedding 64 bits into an image while taking into account the H VS. The proposed method is general in that any mask can be adopted. The main advantage of the framework we present is that we demonstrate how to optimally embed a watermark given the constraints imposed by the mask in the spatial domain. This is in sharp contrast with the bulk of publications which embed a watermark in the DCT domain and then truncate or modulate in the spatial domain in order to satisfy masking constraints. The problem with these approaches is that spatial domain truncation or modulation leads inevitably to the degradation of the watermark in the DCT domain. Results indicate that our proposed approach is robust against JPEG compression at a quality factor of 30im-ages of size 64 by 64.
In this paper, we present methods that can be used to conceal errors in corrupt motion JPEG2000 codestreams. Motion JPEG2000 is an intra-frame compression technique and the proposed concealment methods utilize motion ...
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In this paper, we present methods that can be used to conceal errors in corrupt motion JPEG2000 codestreams. Motion JPEG2000 is an intra-frame compression technique and the proposed concealment methods utilize motion compensation to conceal errors. The simulation results indicate that the proposed methods can yield over 10 dB improvement in PSNR.
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