DEVICE AND A METHOD FOR ENCODING AN IMAGE AND CORRESPONDING DECODING METHOD AND DECODING DEVICE

摘要

A method for encoding an image represented in a perceptual color space is described. The image has at least a luminance component. The method includes transforming by a wavelet transform the luminance component to form at least one low frequency subband of wavelet coefficients, reconstructing a low frequency component for at least one spatial area of the low frequency subband, subtracting the reconstructed low frequency component from the wavelet coefficients of the spatial area, quantizing the wavelet coefficients of the spatial area responsive to the threshold, the threshold being proportional to the reconstructed low frequency component of the spatial area and encoding the quantized wavelet coefficients and the low frequency component.

主权项

1. A method for encoding an image represented in a perceptual color space, wherein the image has at least a luminance component, the method comprising:
transforming by a wavelet transform the luminance component to form at least one low frequency subband of wavelet coefficients; determining a low frequency component from the wavelet coefficient(s) of at least one spatial area of the low frequency subband; quantizing and inverse quantizing said determined low frequency component to obtain a reconstructed low frequency component {circumflex over (L)}lf for the at least one spatial area; subtracting the reconstructed low frequency component from the wavelet coefficients of the spatial area; quantizing the wavelet coefficients in the spatial area responsive to a threshold, wherein said threshold is proportional to the reconstructed low frequency component {circumflex over (L)}lf; and encoding the quantized wavelet coefficients and the low frequency component.