Scalable coding for interactive transmission of images over networks

This dissertation presents a new region-based scalable coding technique that can be used in interactive image/video communications. Our scalable coding scheme provides the capability to use near lossless coding of a specific region of interest (ROI) while the rest of the image can be coded with high quality using lossy coding.; The proposed technique generates a fully embedded bit stream that provides scalability with high quality for the whole image and it can be used to implement region-based coding as well. We achieve region-based scalable coding by using the wavelet transform, by rearranging the wavelet coefficients into subsets and by using successive quantization. Then we separately code each subset that represents a local area in an image. The embedded bit stream is comprised of a basic layer and many enhancement layers. The enhancement layers add refinement to the quality of the image after it has been reconstructed using the basic layer. The proposed coding technique uses multiple quantizers with thresholds (QT) for layering and it creates a bit plane for each layer. The bit plane is then partitioned into sets of small areas to be coded independently. Run-length and entropy coding are applied to each of the sets to provide scalability for the entire image and high picture quality in the user-specific area of interest.; We apply our scheme to image sequences in the second part of this dissertation. We use first order residual images to reduce the temporal redundancy in the video sequences. We tested this technique by applying it to various test video sequences and we consistently achieved a high level of performance.