Image Coding on a Hexagonal Pyramid with Noise Spectrum Shaping

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Abstract
A hexagonally sampled image is split into a low pass band and nine pass bands of one octave width and sixty degrees angular orientation. The conditions to be satisfied by the filter banks for perfect reconstruction are presented. The human visual system's response to stimuli at differing spatial frequencies is then employed to shape the coding noise spectrum. Rate is allocated under a frequency weighted mean squared error distortion measure. A framework is presented for doing this employing either the power spectral density of the image or the variance of the subbands. Both adaptive and non-adaptive entropy coding simulations are carried out under a Laplacian source distribution. Transparent coding results are presented at rates below 1 bit per pixel.© (1989) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.