Patent ID: 6021216
Filing Date: 2000-02-01
Classification: H04N

Abstract:
A method for reducing noise visibility in a compressed digital video signal by reducing the presence of high-frequency, low-amplitude luminance spatial transform coefficients, comprising the steps of:providing a luminance data signal having luminance data values which represent pixel intensity of images in said compressed digital video signal;said luminance data values extending between low luminance values and high luminance values;processing said luminance data values to increase amplitudes of the low luminance values relatively more than amplitudes of the high luminance values in accordance with a transfer function, thereby obtaining processed luminance data values including processed low luminance values and processed high luminance values;spatially transforming and quantizing the processed luminance data values to provide luminance spatial transform coefficients of said compressed digital video signal;transmitting said luminance spatial transform coefficients to a decoder; and, at said decoder:(a) performing an inverse spatial transform on said transmitted spatial transform coefficients to recover data corresponding to the processed luminance data values, including the processed low luminance values and processed high luminance values; and(b) further processing the processed luminance data values to recover data corresponding to said luminance data values of said luminance data signal by decreasing amplitudes of the processed low luminance values relatively more than amplitudes of the processed high luminance values in accordance with an inverse function of said transfer function.