Multi - Resolution Layered Coding for Real - Time Image Transmission

| We examine the rationale for and systems aspects of using layered coding for the transmission of images and video over heterogeneous communication networks. We advocate Multi-resolution Layered Coding (MLC) and present architectural alternatives that can support it within the scope of existing standards and technologies. Since the premise of layered coding is controlled loss, the issues of error control and concealment are central. We demonstrate that MLC exhibits good error tolerance, eeectively compensating for errors in situations where traditional error con-cealment schemes, based on the interpolation of pixels in adjacent blocks, are ineeective. In particular, MLC yields a higher Peak Signal-to-Noise Ratio (PSNR) than two-layer coding when packet loss occurs in the base layer. Finally, we show that MLC can eeectively exploit eecient network error control strategies which distribute redundancy non-uniformly and provide unequal levels of protection across layers.