Abstract: A method for scalable encoding of a digital image into a base layer and at least one enhancement layer comprising an up-sampling step providing at least one part of an enhancement layer, based on a corresponding part of a lower layer having a lower level than the considered enhancement layer, the area of said corresponding parts having a scale factor of 4p (p?1), the lower layer comprising at least one Largest Coding Unit divisible into Q smaller Coding Units, said units being further divisible into K Prediction Units called lower Prediction Units. For a Largest Coding Unit of said lower layer not divided into smaller Coding Units, and having Prediction Units of different sizes, the corresponding portion of said enhancement layer, is divided into K subdivisions having substantially equivalent proportions as the Prediction Units of different sizes.

Abstract: A method of encoding or decoding at least part of a high dynamic range image, the image being defined in a perceptual space of high dynamic range having a luminance component and a color difference metric, the method comprising for a block of the at least part of the image: converting reference samples for prediction of the block into the LDR space of the block to be predicted, the reference samples having been previously reconstructed in their associated LDR space, and predicting the block using the converted reference samples, for encoding or decoding of the block using an encoding or decoding technique applicable to an LDR image.

Abstract: 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.

Abstract: One embodiment concerns a method for generating a media fragment request for requesting fragments of an encoded media stream stored on a server device, the method being implemented by a client device storing a structure representative of fragments of the media stream previously received and stored on the client device. The structure includes first and second types of addressing information associated with fragments already received. The method for generating a media fragment request includes forming a media fragment request to obtain missing media data corresponding to a new fragment of the media stream, the media fragment request specifying at least one piece of addressing information of the first type and at least one addressing information of the second type, wherein the first type of addressing information is spatial or temporal information and wherein the second type of addressing information is byte position information within the media stream.

Abstract: The invention in particular concerns a method and a device for estimating a level of use of a communication network linking a server and at least one client, said communication network being used to transmit a data stream at a transmission rate corresponding to the temporal frequency of said data stream, said data stream comprising at least one item of information characterizing a theoretical rate dependent on said transmission rate of said data stream. After having obtained (121) said theoretical rate of said data stream, the real reception rate of at least one part of said data stream is evaluated (109). Said theoretical rate and said evaluated rate are then compared (113) to estimate said level of use of said communication network. The level of subscription of a client to multicast sessions may be adapted according to the level of use of the communication network.

Abstract: The present invention generally relates to a method and device for tone-mapping an image. The method is characterized in that it comprises: obtaining (12) a residual image by dividing the image by a backlight image determined (11) from the image, and obtaining (13) a tone-mapped image by tone-mapping to the residual image.

Abstract: A method and device for encoding or decoding a picture block having a luminance component. The method includes obtaining a luminance residual block (Lr) by subtracting a first representation (Ll, LlD) of an average value of the luminance component calculated from the luminance component, obtaining a second representation (f(Ll), f(Ll)D) of the average value by applying a transfer function to the average value (Ll) of the luminance component in order to reduce the dynamic range of the average value and encoding a luminance block (Le) obtained by adding (105, 302) together the luminance residual block (Lr) and the second representation (f(Ll), f(Ll)D) of the average value.

Abstract: A method and device for encoding at least part of an image of high dynamic range defined in a perceptual space having a luminance component and a color difference metric, the method comprising: encoding a segment of the at least part of the image using a encoding process applicable to a low dynamic range (LDR) image by applying a coding parameter set including at least one coding parameter; reconstructing the encoded segment in the perceptual space of high dynamic range; evaluating a rate distortion cost for the encoded segment in the perceptual space of high dynamic range; and adjusting said coding parameter set for the encoding process of the segment based on the evaluated rate distortion cost. A corresponding decoding device and method is also provided.

Abstract: The present invention generally relates to a method and device for encoding an image. The method comprises: encoding (12) a backlight image determined (11) from the image; obtaining (13) a residual image by dividing the image by a decoded version of the backlight image, obtaining (16) a tone-mapped residual image by tone-mapping the residual image; and encoding (19) the tone-mapped residual image. The invention relates also to a method and device for decoding a bitstream representing a residual image calculated by dividing an image by a backlight image.

Abstract: The present disclosure generally relates to a method and device for encoding an image block, characterized in that it comprises: obtaining (101) a low-spatial-frequency version (Llf) of a luminance component of the image block, said the obtained luminance component of the image block; obtaining a quantized luminance component (Lif,Q) of the image block by quantizing (102) the obtained luminance component (Llf) of the image block; obtaining (103) a differential luminance component (Lr) by calculating the difference between the luminance component (L) of the image block and either the quantized luminance component (Lif,Q) of the image block or a decoded version (Lif,Q) of the encoded quantized luminance component of the image block; encoding (104) the quantized luminance component (L,if,Q of the image block using at least one frequency coefficient of a set of frequency coefficients which is usually obtained from a block-based spatial-to-frequency transform for encoding the luminance component of the image block

Abstract: 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.

Abstract: Receiving on a communication device a multimedia data stream composed of a sequence of multimedia data segments from a plurality of data sources, each multimedia data segment having an execution time slot relative to an execution time slot of an initial multimedia data segment of the sequence. Receiving and executing a first multimedia segment, requesting the data source of a subsequent multimedia data segment to transmit a portion of the subsequent multimedia data segment, determining therefrom the transmission capability between the communication device and the data source determining a time to start downloading the subsequent multimedia data segment based on its execution time slot relative to the current time slot and the transmission capability, and downloading, at the determined time, the subsequent multimedia data segment for execution during the execution time slot.

Abstract: A method for transitioning between an image of a first video sequence and an image of a second video sequence, wherein an image of the video sequences corresponds to one sub-region of a respective image of the other video sequence, receiving one image from the first video sequence; providing, from the one image, one pre-transition image; for each one pre-transition image: determining a confidence region within the one pre-transition image based on a set of confidence values, each confidence value representing, for a respective block of the one pre-transition image, the level of reliability of determining one or more blocks of a corresponding image in the second video sequence; computing a transition image corresponding to the second video sequence, the transition image being a function of the determined confidence region of the pre-transition image; and displaying the transition image for a duration upon the reception of the second video sequence.

Abstract: A method of coding a sequence of images comprises at least one image comprising an image region of interest. The coding method comprises the following steps implemented for said at least one image of said sequence of images: determining (S10 to S23) an image portion comprising the image region of interest on the basis of a rate-distortion criterion representing a compromise between the compression efficiency the distortion of the image portion and the compression efficiency the distortion of the whole of said at least one image; and coding (S24) said at least one image on the basis of the determined image portion.

Abstract: A frame of pixels is segmented into a plurality of blocks each having a block type by a method including the steps of: a) performing an initial segmentation of the frame into a set of initial blocks, thus determining, for each initial block, a block type associated with the concerned initial block; b) determining, for each block type, an associated set of quantizers based on data corresponding to pixels of blocks having said block type; c) selecting, among a plurality of possible segmentations defining an association between each block of this segmentation and an associated block type, the segmentation which minimizes an encoding cost estimated based on a measure of the rate necessary for encoding each block using the set of quantizers associated with the block type of the encoded block according to the concerned segmentation.

Abstract: The method for transmitting video data encoded in a scalable video stream representing said video data in a plurality of layers, comprises, for at least one layer: a step of obtaining (317) pre-encoded macroblocks of said scalable video stream representing said video data in a plurality of layers, a step of grouping (319) macroblocks, used for inter layer prediction, of the pre-encoded macroblocks obtained by the obtaining step, into first groups of macroblocks, a step of grouping (319) macroblocks, not used for inter layer prediction, of the pre-encoded macroblocks obtained by the obtaining step, into second groups of macroblocks, a step of estimating a loss variability over a network, a step of selecting (331) groups of macroblocks from the first and second groups of macroblocks based on the loss variability estimated by the estimating step and a step of transmitting (333) the groups of macroblocks selected by the selecting step over the network.

Abstract: A method for scalable encoding of a digital image into a base layer and at least one enhancement layer comprising an up-sampling step providing at least one part of an enhancement layer, based on a corresponding part of a lower layer having a lower level than the considered enhancement layer, the area of said corresponding parts having a scale factor of 4p (p?1), the lower layer comprising at least one Largest Coding Unit divisible into Q smaller Coding Units, said units being further divisible into K Prediction Units called lower Prediction Units. For a Largest Coding Unit of said lower layer not divided into smaller Coding Units, and having Prediction Units of different sizes, the corresponding portion of said enhancement layer, is divided into K subdivisions having substantially equivalent proportions as the Prediction Units of different sizes.

Abstract: A method for encoding at least one block of pixels includes the following steps of transforming (18) pixel values for the block into a set of coefficients each having a coefficient type; determining, for each coefficient type, an estimated value representative of a ratio between a distortion variation provided by encoding a coefficient having the concerned type and a rate increase resulting from encoding the coefficient; subjecting coefficients of the set to a quantization step to produce quantized symbols, wherein the subjected coefficients form a subset of the set and wherein the estimated ratios for coefficient types of coefficients in the subset are larger than the highest estimated ratio over coefficient types of coefficients not included in the subset; encoding (193) the quantized symbol. Corresponding decoding method, encoding and decoding devices are also provided.

Abstract: Video coding in which at least two bandwidth values are obtained. A base layer is coded so that a rate of the coded base layer data is less than or equal to the lowest bandwidth. For at least one bandwidth greater than the lowest bandwidth, at least one enhancement layer is coded so that the sum of a rate of the data of the coded enhancement layer and a rate of a subset of data of a reference layer serving as a reference for interlayer prediction of the enhancement layer is less than the bandwidth greater than the lowest bandwidth.

Abstract: A method and device for extracting, from a metadata component associated with a media resource, a metadata fragment associated with a given media fragment of the media resource, the method comprising and the device comprising means for obtaining at least one search expression, for finding the metadata fragment in the metadata component, based on the type of extraction parameters related to a request for obtaining the media fragment from the media resource and the structure of metadata component; parameterization of the or each obtained search expression with values based on values of the extraction parameters and extracting from the metadata component the metadata fragment using the or each parameterized search expression.