Current Issue : January - March Volume : 2013 Issue Number : 1 Articles : 5 Articles
Combining the color difference formula of CIEDE2000 and the printing industry standard for visual verification, we present\r\nan objective color image quality assessment method correlated with subjective vision perception. An objective score conformed to\r\nsubjective perception (OSCSP) Q was proposed to directly reflect the subjective visual perception. In addition, we present a general\r\nmethod to calibrate correction factors of color difference formula under real experimental conditions. Our experiment results show\r\nthat the present DE2000-based metric can be consistent with human visual system in general application environment....
This paper presents a prioritization scheme based on an analysis of the impact on objective video quality when dropping individual\r\nslices from coded video streams. It is shown that giving higher-priority classified packets preference in accessing the wireless media\r\nresults in considerable quality gain (up to 3 dB in tests) over the case when no prioritization is applied. The proposed scheme is\r\ndemonstrated for an IEEE 802.11e quality-of-service- (QoS-) enabled wireless LAN. Though more complex prioritization systems\r\nare possible, the proposed scheme is crafted for mobile interactive or user-to-user video services and is simply implemented within\r\nthe Main or the Baseline profiles of an H.264 codec....
The current trend of digital convergence leads to the need of the video encoder/decoder (codec) that should support multiple\r\nvideo standards on a single platform as it is expensive to use dedicated video codec chip for each standard. The paper presents a\r\nhigh performance circuit shared architecture that can perform the quantization of five popular video codecs such as H.264/AVC,\r\nAVS, VC-1, MPEG-2/4, and JPEG. The proposed quantizer architecture is completely division-free as the division operation is\r\nreplaced by shift and addition operations for all the standards. The design is implemented on FPGA and later synthesized in\r\nCMOS 0.18 �µm technology. The results show that the proposed design satisfies the requirement of all five codecs with a maximum\r\ndecoding capability of 60 fps at 187MHz on Xilinx FPGA platform for 1080 p HD video....
Stereoscopic images are widely used to enhance the viewing experience of three-dimensional (3D) imaging and communication\r\nsystem. In this paper, we propose an image feature and disparity dependent quality evaluation metric, which incorporates human\r\nvisible system characteristics. We believe perceived distortions and disparity of any stereoscopic image are strongly dependent\r\non local features, such as edge (i.e., nonplane areas of an image) and nonedge (i.e., plane areas of an image) areas within the\r\nimage. Therefore, a no-reference perceptual quality assessment method is developed for JPEG coded stereoscopic images based\r\non segmented local features of distortions and disparity. Local feature information such as edge and non-edge area based relative\r\ndisparity estimation, as well as the blockiness and the edge distortion within the block of images are evaluated in this method.\r\nSubjective stereo image database is used for evaluation of the metric. The subjective experiment results indicate that our metric\r\nhas sufficient prediction performance....
Broadband wireless technology, though aimed at video services, also poses a potential threat to video services, as wireless channels\r\nare prone to error bursts. In this paper, an adaptive, application-layer Forward Error Correction (FEC) scheme protects H.264/AVC\r\ndata-partitioned video. Data partitioning is the division of a compressed video stream into partitions of differing decoding\r\nimportance. The paper determines whether equal error protection (EEP) through FEC of all partition types or unequal error\r\nprotection (UEP) of the more important partition type is preferable. The paper finds that, though UEP offers a small reduction in\r\nbitrate, if EEP is employed, there are significant gains (several dBs) in video quality. Overhead from using EEP rather than UEP\r\nwas found to be around 1% of the overall bitrate. Given that data partitioning already reduces errors through packet size reduction\r\nand differentiation of coding data, EEP with data partitioning is a practical means of protecting user-based video streaming. The\r\ngain from employing EEP is shown to be higher quality video to the user, which will result in a greater take-up of video services.\r\nThe results have implications for other forms of prioritized video streaming....
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