Filter design for the interpolation of highly subsampled pictures

摘要

In some of the proposed HDTV bandwidth reduction schemes, such as MUSE, HDMAC and wideband MAC, images are highly subsampled. Interpolation filters have to be applied for the reconstruction. Dependent on the subsampling grid, they are composed of several polyphase components. The gain of each polyphase component has to be one. It is also desirable that the polyphase component fulfill an additional constraint: In case the same filtering and subsampling process has to be applied twice or many times, the values of the picture elements selected by the subsampling process for transmission must not be affected by the applied filters. A method for construction of these filters is presented. The additional constraint and the implications from the recovery requirement are discussed and similarities to the Nyquist pulse-shaping criterion in digital signaling are pointed out.