Methods and devices for coding and decoding images, computer program implementing them and information carrier enabling their implementation

A method of decoding at least one current macroblock of a digital image, to form the current macroblock at a higher resolution level of said digital image, the method comprising:

• a step of determining in a frequency domain at least one low frequency coefficient on the basis of a second macroblock predictor, wherein the second macroblock predictor for a current block corresponds to a macroblock of a resolution level lower than the resolution level of the current macroblock, a step of decoding at least one motion vector, a step of determining one or more first macroblock predictors for the current block on the basis of each decoded motion vector and on the basis of at least one reference image, a step of determining in the frequency domain at least one high frequency coefficient on the basis of coefficients of a transform, to the frequency domain, of at least one of the first macroblock predictors, and a step of transforming, to a spatial domain, said low and high frequency coefficients.

A device for coding a digital image, that comprises:

• a motion estimator that performs an estimation of motion between at least one current macroblock of said digital image and at least one reference image, to obtain one or more first macroblock predictors for a current block in each reference image, a means for obtaining, for said at least one current macroblock, a second macroblock predictor of a spatial scalability level lower than a spatial scalability level of the current macroblock, a means for transforming, from a spatial domain to a frequency domain, at least one of the one or more first macroblock predictors, a low frequency predictor for predicting in the frequency domain at least one low spatial frequency coefficient on the basis of the second macroblock predictor, and a high frequency predictor for predicting in the frequency domain, for the current macroblock, at least one high spatial frequency coefficient on the basis of at least one high frequency coefficient of the transformed one or more first macroblock predictor.

A device for decoding a digital image that comprises:

• a means for determining in a frequency domain at least one low frequency coefficient on the basis of a second macroblock predictor for a current block, wherein the second macroblock predictor corresponds to a macroblock of a resolution level lower than a resolution level of a current macroblock of the digital image, a decoder for decoding at least one motion vector for the current macroblock, a means for determining one or more first macroblock predictors for the current macroblock, on the basis of each decoded motion vector and on the basis of at least one reference image, a means for determining in the frequency domain, for the current macroblock, at least one high frequency coefficient on the basis of coefficients of a transform, to the frequency domain, of at least one of the one or more first macroblock predictors, and a means for transforming, for the current macroblock, to a spatial domain, said low and high frequency coefficients.