This paper presents a method to video conference quality assessment, which is based on cooperative sensing of video and audio. In this method, a proposed video quality evaluation method is used to assess the video frame quality. The video frame is divided into noise image and filtered image by the bilateral filters. It is similar to the characteristic of human visual, which could also be seen as a low-pass filtering. The audio frames are evaluated by the PEAQ algorithm. The two results are integrated to evaluate the video conference quality. A video conference database is built to test the performance of the proposed method. It could be found that the objective results correlate well with MOS. Then we can conclude that the proposed method is efficiency in assessing video conference quality.
A multi-layer coding algorithm is proposed for grey image lossless compression. We transform the original image by a set of bases (e.g., wavelets, DCT, and gradient spaces). Then, the transformed image is split into a sub-image set with a binary tree. The set include two parts: major sub-images and minor sub-images, which are coded separately. Experimental results over a common dataset show that the proposed algorithm performs close to JPEG-LS in terms of bitrate. However, we can get a scalable image quality, which is similar to JPEG2000. A suboptimal compressed image can be obtained when the bitstream is truncated by unexpected factors. Our algorithm is quit suitable for image transmission, on internet or on satellites.
A remote sensing image classification algorithm based on image activity measure is proposed, which is used for adaptive image compression applications. The image activity measure has been studied and the support vector machine(SVM) is introduced. Then, the relationship between the image activity measure and the distortion caused by quantization is discussed in our image compression experiments (JPEG2000, CCSDS and SPIHT). Another two image activity measures are proposed as well. Then a feature vector is constructed by image activity measures in order to describe the image compression features of different images. The test images are classified by support vector machine classifier. The effectiveness of the proposed algorithm has been tested using an image data set, which demonstrates the advantage of the proposed algorithm.
This paper illustrates a forward-flipping architecture for lifting-based discrete wavelet transform (DWT), in which the multiplication and addition operations are flipped to different computation paths in each lifting step through forward-flipping, and the critical path of each lifting step is shortened to one multiplication operation latency. Through case studies on the JPEG2000 default lossy (9,7) filter and the (6,10) filter, the efficiency of the proposed architecture has been demonstrated and confirmed. The comparison results have also shown that the proposed architecture is efficient in reducing the number of pipeline registers for the implementation of DWT under the given timing criteria.
Coherent Target Analysis (CTA) method derived for the (Interferometric SAR) InSAR data processing has developed as one of the critical techniques in the field of surveying subtle land deformation. This paper discusses the principles and characteristics of CTA procedure, which can remove the errors caused by temporal and spatial decorrelation and atmospheric effects. The paper presents the validation of characteristics of CTA applied in city subsidence in Shanghai test site, where has been affected by subsidence for more than eighty years. The 32 scenes from the ERS-1/2 satellites covering the test area between 1992 and 2000 were chosen and processed. Based on the theory of CTA, we can get the map of land subsidence of Shanghai. Quality assessment between the velocity fields derived of CTA and that of leveling data observed on benchmarks within the same periods is then discussed. The comparison with ground leveling data shows the derived result from CTA approach is consistent with leveling data. The further investigation of CTA approach in Shanghai will be continued to improve the accuracy and robustness.