Patent ID: 8559511
Filing Date: 2013-10-15
Classification: H04N

Abstract:
1. A video coding apparatus, comprising: a unit for providing a video signal; a prediction mode determination unit that determines whether a frame in the video signal is an inter frame or an intra frame according to the prediction mode of the frame; an adaptive block-size transform (ABT)-based just noticeable difference (JND) model generation unit that makes use of one or more performance properties of how humans perceive things visually for different block-size based transforms and computes block types, block categorizations and motion vectors for block of different sizes to generate an ABT-based JND model which contains one or more JND thresholds as determined by a psychophysical experiment based on the visual perception model; and an ABT-based JND filter that filters one or more residual coefficients by discarding one or more residual coefficients which are below the JND thresholds of the ABT-based JND model and subtracting the JND thresholds from one or more residual coefficients which are larger than the JND thresholds of the ABT-based JND model so that a signal with filtered residual coefficients is output; wherein the one or more JND thresholds are thresholds over which an observer of the output signal with filtered residual coefficients starts to notice any distortion; and wherein the one or more JND thresholds are modeled by where: T (m, n) denotes the position of DCT block in an image; s denotes the summation effect factor; φ φ ω γ denotes the oblique effect factor; and a, b and c are selected so as to achieve a least mean squared error in fitting JND thresholds obtained from a psychophysical experiment with the values obtained by computing T