Wireless video is one of the important applications supported by upcoming 3G mobile communication systems. In this paper, we propose a fast and memory efficient DCT-domain video transcoder to convert a high quality MP...
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Wireless video is one of the important applications supported by upcoming 3G mobile communication systems. In this paper, we propose a fast and memory efficient DCT-domain video transcoder to convert a high quality MPEG2 video bit stream into a low bit rate MPEG4 stream with low spatial resolution for wireless video access. Compared to existing approaches, the proposed video transcoder can save more than 50% of required memory. Furthermore, the computational complexity of the proposed method is less than 30% of that required by existing methods. However, the video quality achieved by the proposed method and by existing methods is hardly distinguishable for target bit rates of 384 kb/s and 256 kb/s, as shown in our experimental results.
The human visual system has a lower spatial resolution in the periphery than in the fovea. This property may be useful to reduce system bandwidth in applications where the observers' fovea is allowed to scrutinize...
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The human visual system has a lower spatial resolution in the periphery than in the fovea. This property may be useful to reduce system bandwidth in applications where the observers' fovea is allowed to scrutinize a very small portion of a picture. For example, an image frame in a video or movie is presented for less than 100 milliseconds. When viewed with such a short duration, most parts of the frame is seen by the peripheral retina. Since the resolution of the spatial resolution is low, one could reduce information in image areas that will be viewed by the periphery without causing perceptible image degradation. The purpose here is to present a quantitative metric for evaluating the image quality for such non-uniform degradations, by considering visual performance in the periphery. According to this metric, the image difference between the degraded image and the original is decomposed into five levels of pyramid error images based on a measured or assumed fixation position. The contrast of each error image is scaled by a contrast threshold map that is a function of spatial frequency, eccentricity, and image content. Finally, the perceived image degradation is calculated as the square root of the sum of the mean squared contrast over levels and color channels. Experiments were conducted to obtain subjective image quality with non-uniformly degraded images using two different algorithms. Five observers participated in the experiment and were instructed to rate the image quality on a ratio scale. The resulting image quality metric accounts for 92% of the variance in the image quality ratings. As a benchmark, RMS difference accounts for only 67% of the variance.
The objective of this research is to propose a data hiding method for printed images. Three digital halftoning techniques Floyd-Steinberg error diffusion (FSED), multi-scale error diffusion (MSED) and modified multi-s...
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This paper describes the application of the combined knowledge on colorimetry, colour imaging (visualization) and colour perception in an aviation related research project. It involves the optimisation of the conspicu...
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ISBN:
(纸本)0892082399
This paper describes the application of the combined knowledge on colorimetry, colour imaging (visualization) and colour perception in an aviation related research project. It involves the optimisation of the conspicuity of the colour scheme of an airplane, with the purpose of minimizing the changes of a mid-air collision. Subjects determined the conspicuity (here defined as object detection in the visual periphery) of different airplane colours at a simulated distance of 1 km and for different simulated atmospheric visibilities. Results indicate that the conspicuity depends on the lightness difference between the airplane and its background, but not on the difference in hue or saturation.
Video transcoding is an efficient way for rate adaptation and format conversion in various networked video applications. Several transcoder architectures have been proposed to achieve fast processing. Recently, thanks...
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Watermarking is a technique used to label digital media, to protect copyright ownership, by hiding information into the signal. Watermarks must be imperceptible and robust against attacks. Besides, watermark robustnes...
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ISBN:
(纸本)0769516238
Watermarking is a technique used to label digital media, to protect copyright ownership, by hiding information into the signal. Watermarks must be imperceptible and robust against attacks. Besides, watermark robustness against several signal processing techniques can be ensured by exploiting a technique related to the spread spectrum communications. In this paper, we propose a procedure based on frequential substitution using a BPSK modulation with an adaptive carrier frequency, the choice of which depends on the original signal features. A secret key, generated during watermarking process, is used for retrieving hidden information.
作者：
Atta, RGhanbari, MUniv Essex
Dept Elect Syst Engn Audio & Video Networking Res Lab Colchester CO4 3SQ Essex England
In this paper, we introduce a multilayered video coding technique to provide spatial scalability. The proposed scheme generates multilayered bitstreams for scalable multicast video transmission in heterogeneous enviro...
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ISBN:
(纸本)0780374029
In this paper, we introduce a multilayered video coding technique to provide spatial scalability. The proposed scheme generates multilayered bitstreams for scalable multicast video transmission in heterogeneous environments as well as overcomes the major drawback of layered coding which is the increase in the total bit rate. We also minimize the picture drift problem associated with the lower resolution layer by introducing a separate drift compensation layer. Simulation results show that the drift compensation layer improves the lower resolution layer quality without significantly affecting the higher layer coding efficiency. Compared to H263+, although our coder generates more bits at the base layer, but the overall bit rate is less than that of H263+.
This Volume III of IV of the conference proceedings contains 274 papers. Topics discussed include wireless access and networking, source and channel coding, fading and diversity, space time coding, blind multi-user de...
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This Volume III of IV of the conference proceedings contains 274 papers. Topics discussed include wireless access and networking, source and channel coding, fading and diversity, space time coding, blind multi-user detection, coding and linear precoding, channel estimation and equalization, CDMA, OFDM systems, space time/MIMO channel equalization, capacity and performance analysis, space-time coding, estimation and demodulation, source and channel coding, OFDM and DMT systems, channel estimation and equalization, application-specific systems and implementation, spread-spectrum, CDMA and multi-carrier systems, compression, coding and modulation, source and channel modleing and estimation, space-time processing for communications, radar and sonar processing, adaptive beamforming and space-time processing, beam forming and spatial filtering, detection and estimation, direction-of-arrival estimation, blind source separation, VLSI algorithms and architecture for communication coding, VLSI architectures for video and imageprocessing, design methodologies for DSP architectures and systems and high performance DSP architectures.
One interesting feature of the new JPEG2000 image coding standard is support of region of interest (ROI) coding using the maximum shift (Maxshift) method, which allows for arbitrarily shaped ROI image compression with...
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One interesting feature of the new JPEG2000 image coding standard is support of region of interest (ROI) coding using the maximum shift (Maxshift) method, which allows for arbitrarily shaped ROI image compression without shape coding or explicitly transmitting any shape information to the decoder. The major disadvantage of the Maxshift method is that it cannot adjust the scaling value which determines the degree of relative importance between the ROI and the background wavelet coefficients. The bitplane-by-bitplane shift (BbBShift) method was introduced to support both arbitrary ROI shape and arbitrary scaling without shape coding. In this paper, we propose a generalize BbBShift (GBbBShift) method, which delivers much more flexibility than both Maxshift and BbBShift for "degree-of-interest" adjustment of the ROI with insignificant effect on coding efficiency and computational complexity. Experiments show that it can provide significantly better visual quality than Maxshift at low bit rates. GBbBShift is not compliant with the current JPEG2000 definitions. In order to use it, a new ROI coding mode would need to be added to the standard.
The video segmentation problem can be regarded as a problem of detecting the fundamental video units (shots). Due to different ways of linking two consecutive shots this task turns out to be difficult. In this work, w...
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