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Image distortion can be categorized into two aspects: content-dependent degradation and content-independent one. An existing full-reference image quality assessment (IQA) metric cannot deal with these two different impacts well. Singular value decomposition (SVD) as a useful mathematical tool has been used in various image processing applications. In this paper, SVD is employed to separate the structural...
We propose a new no-reference image quality assessment model nPSNR (No-reference PSNR) for JPEG compressed images. The model performs in DCT domain and the DCT coefficient distribution is used. This method estimates the MSQE (mean-squared quantization error) of a decoded image with the distributions of AC coefficients and DC coefficients of the encoded image, for PSNR estimation in DCT domain without...
In this work, a sample rate estimator is proposed for selective graphics rendering so that the samples are allocated such that the best perceived image quality can be achieved under a given sample budget. In the proposed estimator, the sample rate of a pixel is decided by not only the visual attention (VA) level of the region to which the pixel belongs but also the required rendering complexity (RC)...
The existing image compression methods (e.g., JPEG2000, etc.) are vulnerable to bit-loss, and this is usually tackled by channel coding that follows. However, source coding and channel coding have conflicting requirement. In this paper, we address the problem with an alternative paradigm, and a novel compressive sensing (CS) based compression scheme is therefore proposed. Discrete wavelet transform...
This paper presents a framework for video coding, which is compatible with the existing H.264/AVC standard (for preprocessing). Since the video sequences are of 3D data matrices and the traditional XY image frame plane is not always the best for video coding in terms of rate-distortion (RD) performance, optimal compression plane (OCP) determination models are developed to improve the coding efficiency...
We propose a unified deblocking/error-concealment algorithm for simultaneously alleviating blockiness and restoring lost blocks. Blockiness and block loss are two of the most frequently encountered artifacts for block-DCT based visual signal coding and transmission. The problem of error-concealment and deblocking is formulated as block-wise expectation estimation processes conditioned on available...
In this paper, the problem of concealing missing image/video blocks is casted into a framework of Bayesian estimation. The conditional expectation of the missing block vector is taken over a pilot vector of correctly decoded pixels near the missing block. Multiple observations of the missing vector and pilot vectors obtained in a nonlocal manner are used to approximate the expectation. We design a...
We propose to use Block-based Bilateral Filter (BBF), which extends the classical Bilateral Filter (BF) through operating in block-wise manner, to conceal missing image blocks in the application of compressed image transmission over wireless channels. We show that the problem of error-concealment using BBF can be considered as a superset of image denoising using BF. The BBF has the ability to capture...
Since the coding residues correlates with the coded image, we propose a model for compression residue estimation with the coded image. When used for postprocessing, it results in a LMS (least mean square) process which can be implemented as filtration similar to most existing techniques, but gives more theoretical insight and restores residues without any assumption of the coding distortion (i.e.,...
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