Abstract: A method for generating at least one image with a first dynamic range, from an image with a second dynamic range, which is lower than the first dynamic range is described. The method includes obtaining an epitome of the image with a first dynamic range, called a first epitome. Thereafter, the image with a first dynamic range is generated from the image with a second dynamic range and the first epitome.

Abstract: A method for encoding a current image in an image set is disclosed. The method incudes accessing a reference image for the current image, determining at least one prediction image wherein a prediction image is obtained from a geometric transform applied to the reference image, the prediction image being a prediction for at least one region of current image, encoding the current image based on the at least a prediction image using block matching compensation, generating a bitstream comprising the encoded image, an item representative of the reference image and an item representative of the at least one geometric transform.

Abstract: The method includes determining at least one candidate motion vector associated with a neighboring block of said current block. A prediction motion vector is determined from the candidate motion vector, and the current block is coded from the prediction motion vector. The prediction motion vector is determined according by determining, for the candidate motion vector, a corrective motion vector so as to minimize a distortion calculated between the neighoboring block successively coded and reconstructed and a prediction block motion compensated by the at least one candidate motion vector modified by the corrective motion vector. The prediction motion vector is then determined from the candidate motion vector modified by the corrective motion vector.

Abstract: A method for encoding a plenoptic image divided into blocks is disclosed. The method comprises: —encoding (S120) a block in a central region of the plenoptic image, called central block, without spatial prediction; and—predictively encoding (S130) blocks immediately surrounding said central block by spatially interleaving spatial unidirectional prediction and spatial bi-directional prediction.

Abstract: Clustering patches of a degraded version of an image is such that the clusters are based on errors computed between patches of the degraded version processed with upgrade functions associated respectively with the clusters and patches of a full graded version of the image corresponding respectively to the patches of the degraded version. The source image is thus used to determine clusters for the image to restore. A restoration framework based on a clustering according to the present principles is also disclosed.

Abstract: The present disclosure generally relates to a method for reducing the coding artefact of at least one pixel of a view (170) belonging to a matrix of views (17) obtained from light-field data associated with a scene. According to present disclosure, the method is implemented by a processor and comprises for each said at least one pixel: —from said matrix of views (17), obtaining (51) at least one epipolar plane image (EPI) associated with said pixel, —applying (52) an artefact filtering on pixels of said epipolar plane image (EPI), —redistributing (53) the filtered pixels of the epipolar plane image in the matrix of views (17).

Abstract: The present disclosure generally relates to a method for predicting at least one block of pixels of a view (170) belonging to a matrix of views (17) obtained from light-field data belong with a scene, According to present disclosure, the method is implemented by a processor and comprises for at least one pixel to predict of said block of pixels: —from said matrix of views (17), obtaining (51) at least one epipolar plane image (EPI) belong with said at least one pixel to predict, —among a set of bidirectional prediction modes, determining (52) at least one optimal bidirectional prediction mode from a set of previous reconstructed pixels neighbouring said at least one pixel to predict in said at least one epipolar plane image, —extrapolating (53) a prediction value of said at least one pixel to predict by using said at least one optimal bidirectional prediction mode.

Abstract: A method for encoding a current focal stack is disclosed that comprises a set of images focused at a different focalization distance from one image to another. According to present disclosure, the method comprises: —encoding (31) information representing an image of the current focal stack, the image being selected in said current focal stack according to an image sharpness criterion, and reconstructing the image into a reconstructed image; —encoding (32) at least another image of the current focal stack by prediction from at least the reconstructed image.

Abstract: The invention relates to a method and device for quantising the floating value of a pixel of an image by rounding either to a lesser whole number, to a greater whole number, or to the whole number closest to this floating value. The method is characterised in that the selection of rounding this floating value is determined based on a test value.

Abstract: A method comprises, building (S715) a first intermediate patch of a low dynamic range; building (S725) a second intermediate patch of a high dynamic range; building (S735) a patch by applying a transfer function to a transformed initial patch of the base layer in a transform domain and then applying an inverse transform to the resulting patch so as to return in a pixel domain; predicting (S740) a prediction of the current block of the enhancement layer by extracting a block from the patch; and encoding a residual error between the current block of the enhancement layer and the prediction of the current block of the enhancement layer.

Abstract: A method is proposed for filling-in missing regions in an image of a multimedia content. Such method comprises, for a block x comprising a patch xa of known pixels and a patch xu of unknown pixels: obtaining (300) a set {yi} of N blocks of pixels; splitting (310) the set {yi} for providing a set {yia}, respectively {yiu}, of N patches referring to pixels in the set {yi} having the same relative spatial positions as xa, respectively xu, in x; determining (320) a fill-in patch yfill based on an optimization of an objective function subject to a boundary smoothness constraint taking into account at least one isophote vector estimated at position of at least one pixel p in xa for insuring a smooth transition between the patches xa and xu; filling-in (330) missing regions in the image by associating the patch yfill to the patch xu.

Abstract: A method for enhancing quality of an image comprises deriving from an initial low-resolution image (LRI) an initial high-resolution image (IHRI) by upsampling (S2, S3), providing (S4), based on the initial low-resolution image (LRI), at least one downsampled filtered image (AIij, AIi?j?) with lower resolution, providing (S6), based on the initial low-resolution image (LRI), an unfiltered image (LRI, UIi?j?) having same resolution as the downsampled filtered image, selecting a patch (PI) from the initial high-resolution image (IHRI), finding (S8) filial patches (PA k) similar to the selected patch in the downsampled filtered image (AIij, AIi?j?), finding, in the unfiltered image (LRI, UIi?j?), parent patches (PPk) locally associated to the filial patches (PAk), and linearly combining (S14) the parent patches (PPk) to form an enhanced quality patch (EP).

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 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 of encoding a video image includes, for each one of blocks of the video image, calculating virtual gradient values in the block depending on neighboring gradient values computed in a causal neighborhood of the block and acquiring one prediction direction or non-directional intra prediction mode based on the virtual gradient values; and determining a coding mode by comparing different predictions for the block, acquiring a predicted block by applying the determined “coding mode”, acquiring a residual error between the predicted block and the current block and encoding a difference between the determined coding mode and the prediction direction or non-directional intra prediction mode. The calculating includes, for each prediction direction, propagating the neighboring gradient values along the prediction direction to estimate the virtual gradient values in the block.

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 neighboring 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: A method for decoding a stream of coded data to reconstruct a current block of a sequence of images is disclosed. The method comprises the steps of: reconstructing for the current block a first item of motion data from a stream of coded data, identifying a first prediction block with the first item of motion data, determining a second item of motion data by template matching, identifying a second prediction block with the second item of motion data, reconstructing the current block from the first and second prediction blocks. The step of determination of the second item of motion data is a function of the first distortion calculated between the first prediction block and the second prediction block.

Abstract: A method (350) includes: applying (S360) inverse tone mapping operations to a block (bb) of a first layer (lb) and to a prediction block (˜bb) of the block (bb) of the first layer (lb), respectively, computing (S365) a residual prediction error (reb) in a second layer (le), and computing (S370) a prediction (pe) of a block of the second layer (le).

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 optimizing 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: The invention relates to a predictive coding/decoding method/device for a group of pictures belonging to a sequence of images, using at least one reference image belonging to a group of pictures other than the group of pictures to code, and converting the values of the pixels of the images of the group of pictures from a configurable transform such that these values are expressed in a target dynamic. The method is characterised in that it converts the values of the pixels of each reference image from the transform thus configured identically to the one used to convert the values of the pixels of the images of the group of pictures to code.