A subjective evaluation of noise-shaping quantization for adaptive intra-/interframe DPCM coding of color television signals

Nonuniform quantizers for just-not-visible reconstruction errors in an adaptive intra-/interframe DPCM (digital pulse-code modulation) scheme for component-coded color television signals are presented, both for conventional and for noise-shaping DPCM. Noise feedback filters that minimize the visibility of reconstruction errors by spectral shaping are designed for Y, R-Y, and B-Y. A closed-form description of the masking function is derived which leads to a one-parameter b-quantizer characteristic. Subjective tests that were carried out to determine visibility thresholds for reconstruction errors for conventional DPCM and for noise shaping DPCM show significant gains by noise shaping. For a transmission rate of around 30 Mb/s, reconstruction errors are almost always below the visibility threshold if variable length encoding of the prediction error is combined with noise shaping within a 3:1:1 system.<
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