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13 December 1976 Quantizer Design Using Visual Thresholds For Dpcm Coding Of Picture Signals
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Visual thresholds play an important role in the process of incorporating properties of the human visual system in encoding picture signals. They tell us how much the picture signal can be perturbed without the perturbations being visible to human observers. We describe psychovisual experiments to determine the amplitude thresholds at a single edge having a given slope. The perturbation of the picture signal caused by the encoding process should not exceed the threshold corresponding to the slope at any picture point, in order that the original and the encoded pictures be visually indistinguishable. We give methods to design quantizers for use in Differential Pulse Code Modulation (DPCM) systems, such that the quantization error is below the threshold and either a) the number ofquantizer levels or b) the entropy of the quantized output is minimized. We also disucss the structure of these quantizers and evaluate their performance on real pictures both in terms of picture quality and entropy.
© (1976) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
D. K. Sharma and A. N. Netravali "Quantizer Design Using Visual Thresholds For Dpcm Coding Of Picture Signals", Proc. SPIE 0087, Advances in Image Transmission Techniques, (13 December 1976);

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