Orange

Mohsen Abdoli

Félix Henry

Felix Henry

Gordon Clare

Pierrick Philippe

A method and device for coding and decoding a coded data stream representative of at least one image split into blocks. For a current block, a group of pixel values in the block is determined from previously decoded pixels, and for each pixel, a prediction residue is decoded. A prediction value for the pixel is determined according to a first prediction mode by predicting the pixel from at least one other previously decoded pixel belonging to the current block. Information is decoded from the stream indicating whether the pixel is predicted according to a second prediction mode using a prediction resulting from the group of pixel values in the block. When the pixel is predicted according the second mode, the prediction value for the pixel is replaced with a selected value of the group. The pixel is reconstructed using the prediction value associated with the pixel and the prediction residue.

Methods and devices for coding and decoding a data stream representative of at least one image

A method for decoding a coded data stream representative of at least one image that is split into blocks. For at least one block of the image, referred to as the current block, an item of information indicating a coding mode of the current block is decoded from the data stream. When the coding mode of the current block corresponds to a first coding mode, decoding a prediction residue associated with the current block using a first group of syntax elements. When the coding mode of the current block corresponds to a second coding mode, decoding the prediction residue associated with the current block using a second group of syntax elements, which is a subgroup of syntax elements of the first group of syntax elements.

Methods and devices for encoding and decoding a data stream representing at least one image

A method for decoding a coded data stream representing an image. The method includes for a current block: reading from the stream a block size threshold value; determining whether the current block size is less than or equal to the threshold value; if so, decoding information indicating a first or second coding mode and reconstructing the current block according to the indicated mode, and if not, reconstructing the current block according to the first mode. In the first mode the current block is reconstructed using an inverse transform of a transformed prediction residue decoded for the current block, and in the second mode the current block is not reconstructed using such an inverse transform, but by: scanning each pixel of the block, including: obtaining a prediction of the pixel from another previously decoded pixel, and reconstructing the pixel from the prediction and a decoded prediction residue.

Methods and devices for coding and decoding a data stream representing at least one image

A method for decoding a data stream representative of an image split into blocks. For a current block of the image, an item of information indicating a coding mode among a first and a second coding mode of the current block is decoded from the data stream and the current block is decoded depending on this information. When the coding mode of the current block corresponds to the second coding mode, the current block is reconstructed from a prediction obtained, for each pixel, from another previously decoded pixel belonging to the current block or to a previously decoded block of the image, and from a decoded residue associated with the pixel. At least one processing method is applied to the reconstructed current block for at least one pixel of the current block depending on the coding mode of the current block and/or the coding mode of the neighbouring blocks.

Methods and devices for encoding and decoding a data stream representing at least one image that disables post-processing of reconstructed block based on prediction mode

A coding method and a decoding method for decoding a coded data stream representative of at least one image that is split into blocks. For at least one current block of the image, an item of information indicating a coding mode of the current block is decoded from the data stream. When the coding mode of the current block corresponds to a first coding mode, the current block is decoded using a first determined quantization step to dequantize, in the transform domain, a prediction residue associated with the current block. When the coding mode of the current block corresponds to a second coding mode, the current block is decoded using a second determined quantization step to dequantize, in the spatial domain, a prediction residue associated with the current block. The first quantization step and the second quantization step are determined according to the same quantization parameter.

A method and device for encoding and a method and device for decoding a signal including encoded data representing an image sub-divided into blocks, and information representing a correction block and a residual block. For a current block of the image, a first pixel is encoded from a prediction value obtained for the first pixel from at least one pixel of a previously rebuilt block. The prediction is corrected using at least one value of a pixel of the correction block. At least one current pixel of the current block is encoded from a prediction value obtained for the current pixel from at least one previously corrected pixel of the current block. The prediction is corrected by using at least one value of a pixel of the correction block, delivering a prediction block for the current block. The residual block is computed from the current block and the predictive block.

A method for decoding a data stream representative of an image split into blocks. The method includes: for a current block, determining whether the size of the current block is less than or equal to a threshold, and if so, decoding information indicating a coding mode of the block among first and second coding modes, and reconstructing the current block according to the indicated coding mode, and otherwise reconstructing according to the first coding mode. According to the first coding mode, the current block is reconstructed using an inverse transform of a transformed prediction residue decoded for the current block, and according to the second coding mode the current block is reconstructed, for each pixel, by obtaining a prediction of the pixel from another previously decoded pixel belonging to the current block or to a previously decoded block, and reconstructing the pixel from the prediction and a decoded prediction residue.

Coding and decoding methods for coding and decoding a coded data stream representing at least one image split into blocks. The method includes, for a current block, determining if the current block is coded according to an intra coding mode or another coding mode, the intra coding mode using an intra prediction mode selected from a group of intra prediction modes, according to an intra prediction mode associated with a neighbouring block of the current block. When coded according to the intra coding mode, an intra prediction mode in the group is determined for the current block, according to an intra prediction mode associated with a previously decoded block of the image. The current block is decoded according to the determined intra prediction mode associated with the current block. When coded according to the other coding mode, the current block is decoded according to the other coding mode.

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Chatillon, France

Mohsen Abdoli