Cyclic Filter Bank Implementations of Symmetric Extension for Subband/Wavelet Image Compression

Symmetric extension is typically employed in subband/wavelet image coders to improve compression performance, particularly at the image boundaries. This paper introduces improvements to the symmetric extension filter bank. The filter bank implementation employs a cyclic frequency domain representation and is able to accommodate IIR approximations that effectively have perfect stopband suppression. Enhancements are also introduced at the multi-rate system level. The new implementation offers greater flexibility in choice of filters and is shown to result in better compression performance.