Abstract: A method and device for predicting a block of pixels of an image for encoding/decoding same. The method comprises a step of defining a causal vicinity of said block to be predicted, a step 2 of searching for candidate patches during which a set of candidate patches is formed from at least one patch belonging to an image other than the image to which the block to be predicted belongs, each patch being formed from a block and from a causal vicinity of said block, and a step 3 of block prediction during which the block is predicted at least from the block of at least one patch of said set of candidate patches.

Abstract: A method for coding a block of pixels is disclosed. The method comprises the following steps: determining, for each pixel of the current block, a prediction pixel by thresholding, with a current threshold value, of coefficients resulting from a transformation applied on a window covering at least the pixel of the current block and by inverse transformation applied to the thresholded coefficients, extracting from the current block a prediction block formed of prediction pixels to generate a residue block, and coding said residue block, According to the invention, the current threshold value is determined or coded from neighboring reconstructed pixels of the current block.

Abstract: The present invention generally relates to a method and device for tone-mapping a video sequence in which a local tone-mapping operator is applied on each frame of the video sequence to be tone-mapped. The method is characterized in that the spatial neighborhoods used by said local-tone-mapping operator are determined on a temporal-filtered version of the frame to be tone-mapped.

Abstract: A method for encoding a sequence of high dynamic range pictures is disclosed. The method comprises for each picture of the sequence: obtaining a value representative of an average luminance of the high dynamic range picture; processing the high dynamic range picture so that the value representative of an average luminance of the processed picture is closer to a defined average luminance value than is the value representative of an average luminance of the high dynamic range picture; decomposing the processed high dynamic range picture in at least one first low dynamic range picture and one second low dynamic range picture of lower resolution representative of a global illumination of the scene; and encoding the first and second low dynamic range pictures and a data function of said value representative of an average luminance of said high dynamic range picture.

Abstract: A method for extracting an epitome from an image Y is described. The method comprises: searching, for each block, a list of patches in the image Y with similar content; determining, for each patch of said lists, the set of blocks able to be represented by the patch; constructing, from the sets of blocks, epitome charts comprising, for each epitome chart, initializing said epitome chart with one patch and extending said epitome chart with at least one candidate region contained in a patch overlapping said epitome chart; said method being characterized in that said candidate region is selected by taking into account the blocks represented by said patch overlapping said epitome chart and by any other patch contained in said epitome chart enlarged by said selected candidate region.

Abstract: A method for predicting a current block belonging to a current image with a view to the coding or the reconstruction of the current block. The method includes determining for the current block a reference block from at least one motion data previously associated with the current block. The fulfillment of a predefined condition is is verified. The predefined condition being representative of a temporal variation between the image data of the reference block and the image data of a prediction block of the reference block previously determined from at least one motion data associated with the reference block. The motion data is modified according to the result of the verification, and a final prediction block for the current block is generated from the motion data of the current block.

Abstract: The invention relates to a method for selecting an image dynamic range conversion operator from among a set of image dynamic range conversion operators by optimising a quality criterion, each image dynamic range conversion operator being applied to an original image to obtain an image, called the modified image, whose dynamic range is lower than that of the original image, wherein said quality criterion is calculated, for each image dynamic range conversion operator, as a function of a distortion calculated from a reconstructed version after coding and decoding the original image modified by said image dynamic range conversion operator.

Abstract: A method for decoding a stream of coded data representative of a sequence of pictures is described. The method comprises the following steps: decoding at least one part of the stream into decoded data, selecting a brightness variation model representative of a brightness variation between the pictures of the sequence from a set of at least two brightness variation models, and reconstructing the picture data from decoded data by taking into account the brightness variation model. A method for coding a picture sequence and a data structure are further disclosed.

Abstract: A method and apparatus for dynamic range expansion of an LDR video sequence are suggested. The suggested method comprises the steps of: acquiring the LDR video sequence and at least one HDR panoramas concurrently, an image in said HDR encompassing a wider field of view than an image in said LDR; determining a dynamic range expansion operator based on the LDR video sequence and the HDR panoramas; and applying the determined dynamic range expansion operator on the LDR video sequence.

Abstract: A method for encoding and decoding an image block, an encoder, and a decoder are provided. The method for encoding an image block comprises: determining a local dynamic range of the block; adaptively precision-extending pixel values of the block based on the local dynamic range of the block; and encoding the block with an adaptively extended precision. The method for decoding an image block comprises: determining a minimum pixel value of the block and an indicating value for indicating a precision extension factor according to precision extension information; decoding the block according to the indicating value; and de-extending precision of the decoded block based on the minimum pixel value of the block and the precision extension factor. The precision of the intermediate calculations may be improved without increasing an original intermediate bit depth used in intermediate calculations.

Abstract: A method for decoding a picture divided into blocks is disclosed. The method comprises at least one iteration of: a) determining for at least two blocks adjacent to a reconstructed part of the picture a priority level responsive at least to directional gradients computed in a causal neighborhood of the block; and b) decoding a part of the picture comprising the block whose priority level is the highest.

Abstract: The present invention generally relates to a method for predicting a block of pixels from at least one patch comprising a block of pixels and a causal neighborhood around this block of pixels. The method comprises the following steps: determining a mapping of a causal neighborhood, around that block of pixels to be predicted, on the block of pixels to be predicted in order that the block of pixels of each patch is best predicted by mapping the neighbourhood of that patch on the block of pixels of that patch, and predicting the block of pixels from a prediction block computed by applying the determined mapping on the neighbourhood of the block of pixels to predict.

Abstract: The invention is made in the field of image block encoding and reconstruction. A method for reconstructing a current block of an image is described, the current block being encoded using predictive encoding of segments resulting from geometry adaptive block partitioning of said current block. After decoding encoded data comprising at least one flag and motion vectors, wherein blocks referenced by the motion vectors are used for prediction of segments of the current block, the at least one flag and an encoding order of the motion vectors in the encoded data is used for determining which of the referenced blocks exhibits a geometry that matches the geometry of the current block and for determining a segment of the determined block, wherein prior to determining the segment, the determined block is geometry adaptive block partitioned into segments from which the segment is determined for predicting one of the segments of the current block.

Abstract: The invention relates to a method for processing a video sequence formed by at least two video images, said method comprising: obtaining said at least two video images using a first capture module with a first field of view, each video image representing a same scene captured at different instants or from different points of view, wherein said method comprises: determining luminance information from at least one overall image obtained by a second capture module with a second field of view greater than said first field of view, said overall image representing the scene captured at different instants or from different points of view, down-converting a dynamic range of said video images taking into account said luminance information.

Abstract: A method and device for predicting a block of pixels of an image for encoding/decoding same. The method comprises a step of defining a causal vicinity of said block to be predicted, a step 2 of searching for candidate patches during which a set of candidate patches is formed from at least one patch belonging to an image other than the image to which the block to be predicted belongs, each patch being formed from a block and from a causal vicinity of said block, and a step 3 of block prediction during which the block is predicted at least from the block of at least one patch of said set of candidate patches.

Abstract: A method for coding a block of pixels is described. The coding method comprises: determining a prediction block for the pixel block from a motion vector; calculating a residue between the pixel block and the prediction block; and code the residue. The determination of the prediction block comprises the following steps: determining an intermediate prediction block of size strictly greater than the size of the pixel block; transforming the intermediate prediction block into a first block transformed with a first transform; and transforming the first transformed block into a second block transformed with a second transform of inverse the first transform whose basis functions are shifted by at least a part of each component of the motion vector, the prediction block being extracted from the second transformed block.

Abstract: A method for constructing an epitome from an image divided into non overlapping blocks is disclosed. The method comprises: determining, for each block, similar patches in the image, a similar patch being a patch with similar content; constructing at least one epitome chart for the picture from the similar patches; wherein determining, for each block, similar patches in the image comprises: a) determining, for each current block, similar blocks in the image, a similar block being a block with content similar to the content of the current block; b) determining, for one current block and for the similar blocks determined for the current block, similar patches in the image, a similar patch being a patch with content similar to the content of the current block; c) repeating step b) for a next current block for which no similar patch is determined until at least one similar patch is determined for each block in the image.

Abstract: A spatial prediction method of a block of pixels of an image, called current block, using a plurality of spatial prediction modes based on neighbouring pixels of the current block is disclosed. The method comprises determining a prediction block of the current block according to each one of said spatial prediction modes and selecting one of said prediction blocks according to a predetermined criterion. According to the invention, before carrying out the preceding steps, it is detected, among said spatial prediction modes, whether some of them are redundant. If such redundant modes are detected, one of them is replaced by an additional mode, distinct from the other spatial prediction modes.

Abstract: The invention relates to a method and a device for converting an original image sequence (SIO) whose luminance values belong to a given dynamic range, said method comprising a step of image-by-image dynamic range conversion during which a dynamic range conversion operator (TMO) is applied to the luminance component (Lw(i)) of each image of the original image sequence (SIO) to obtain a modified luminance component whose values belong to a lower dynamic range than that of the original image sequence (SIO). The method is characterised in that it also comprises a step of correction of the dynamic range during which the dynamic range of the values of the luminance component thus modified is reduced by a value calculated from a global characteristic of the original image sequence.

Abstract: A method for coding or decoding pixel blocks is disclosed. The number of usable modes at the coder and at the decoder is limited to a subset of the set of possible coding modes and the content of this subset is regularly adapted to the content of the images of the sequence. Thus, the coder or decoder always only has a reduced number q<n of coding modes available, called available coding modes, to code or decode the current pixel block but this subset of q coding modes is regularly modified according to the pixel blocks already coded or decoded.