Robust image transmission through wireless commuincation channels using unequal error protection based on adaptive image segmentation

Abstract

Reliable transmission of high quality images through wireless communication channels represents a great challenge, especially for real-time applications. From one aspect, it is necessary to achieve efficient compression that maintains the good image quality without increasing the transmission bandwidth. Secondly, wireless channels impairments such as fading and interference increase the probability of errors when the image data is transmitted. This necessitates the use of efficient channel coding to protect against channel errors. However channel coding results in increasing the transmitted bit rate, for real time applications. Again, this is constrained by the usually limited available transmission bandwidth. In this paper, this dilemma is solved by adopting new unequal error protection techniques that are used to achieve the above requirements by using image adaptive combined compression and error protection. This is achieved through image segmentation and adaptive compression and channel coding according to the importance of the image segments. Two proposed techniques are introduced. In the first suggested technique, the image is partitioned into equal blocks and the data classification is performed in the DCT domain. The DCT coefficients of the different blocks are classified to different classes of importance and hence they are given different rates of error protection and compression ratios. The second technique is based on adaptive image segmentation using quadtree decomposition into unequal segments before applying the DCT. Finally, to improve the quality of received images, the Orientation Adaptive Sequential Interpolation error-concealment technique is applied to the reconstructed images. Computer simulation shows that the proposed techniques achieve high degree of robustness against channel impairments with good image quality with acceptable data rates.