The study of the quality dependence of the decoded image in the JPEG 2000 format on the JPWL parameters and the packet error rate in the noisy channel
Abstract
The study of the quality dependence of the decoded image in the JPEG 2000 format on the JPWL parameters and the packet error rate in the noisy channel
Incoming article date: 08.11.2017This article discusses image transfer in JPEG2000 format using JPWL antinoise coding via noisy channel with occurrence of packet errors. The main problem is recovery of received image with minimum deviations from input original. The aim of this work is to study experimentally the capability of JPWL protection to maintain quality of received and decoded image depending on the level of packet loss in data transmission channel. The experimental procedure consists of simulation of multiple transfer of JPWL protected image with the size of 1024×768 pixels and packet loss with the coded image data. Variable parameters of the study are: JPEG2000 coding procedure (irreversible conversion), Reed–Solomon codes used for JPWL protection, per cent of packet loss. Regular variant of JPWL protection is considered as well as combination of regular variant with algorithm of in-frame interleaving. The final experimental results are PSNR similarity extent of received and decoded image and input image, average per cent of completely recovered tiles with respect to tile number in code stream. The article describes the software complex developed for these studies, which includes JPEG2000 coder and decoder, JPWL coder and decoder, means of code stream dividing into RTP packets, simulating means of packet loss, assembling of frames from RTP packets. Operation flowcharts of JPEG2000 coder and decoder are described. It is mentioned that under conditions of packet errors JPEG2000 decoder should be able to process partially damaged or absent tiles. In-frame interleaving of code stream is described aimed at improvement of its stability with regard to packet errors. Three hypotheses are formulated. Hypothesis 1: in the case of packet loss the regular JPWL extension is unable to maintain quality of received and decoded image. Hypothesis 2: in the case of packet loss the regular JPWL extension in combination with algorithm of in-frame interleaving maintains the quality of received and decoded image. Hypothesis 3: in the case of packet loss and with application of algorithm of in-frame interleaving the PSNR value of received and decoded image depends statistically on the number of tiles completely recovered by JPWL decoder. As a result of the experimental study, all the hypotheses were fully confirmed.
Keywords: JPEG 2000, JPWL, packet errors, noise-immune encoding, decoded image quality