Abstract: To encode High Dynamic Range (HDR) images, the HDR images can be converted to Low Dynamic Range (LDR) images through tone mapping operation, and the LDR images can be encoded with an LDR encoder. The present principles formulates a rate distortion minimization problem when designing the tone mapping curve. In particular, the tone mapping curve is formulated as a function of the probability distribution function of the HDR images to be encoded and a Lagrangian multiplier that depends on encoding parameters. At the decoder, based on the parameters indicative of the tone mapping function, an inverse tone mapping function can be derived to reconstruct HDR images from decoded LDR images.

Abstract: To encode High Dynamic Range (HDR) images, the HDR images can be converted to Low Dynamic Range (LDR) images through tone mapping operation, and the LDR images can be encoded with an LDR encoder. The present principles formulates a rate distortion minimization problem when designing the tone mapping curve. In particular, the tone mapping curve is formulated as a function of the probability distribution function of the HDR images to be encoded and a Lagrangian multiplier that depends on encoding parameters. At the decoder, based on the parameters indicative of the tone mapping function, an inverse tone mapping function can be derived to reconstruct HDR images from decoded LDR images.

Abstract: To encode High Dynamic Range (HDR) images, the HDR images can be converted to Low Dynamic Range (LDR) images through tone mapping operation, and the LDR images can be encoded with an LDR encoder. The present principles formulates a rate distortion minimization problem when designing the tone mapping curve. In particular, the tone mapping curve is formulated as a function of the probability distribution function of the HDR images to be encoded and a Lagrangian multiplier that depends on encoding parameters. At the decoder, based on the parameters indicative of the tone mapping function, an inverse tone mapping function can be derived to reconstruct HDR images from decoded LDR images.

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: To encode High Dynamic Range (HDR) images, the HDR images can be converted to Low Dynamic Range (LDR) images through tone mapping operation, and the LDR images can be encoded with an LDR encoder. The present principles formulates a rate distortion minimization problem when designing the tone mapping curve. In particular, the tone mapping curve is formulated as a function of the probability distribution function of the HDR images to be encoded and a Lagrangian multiplier that depends on encoding parameters. At the decoder, based on the parameters indicative of the tone mapping function, an inverse tone mapping function can be derived to reconstruct HDR images from decoded LDR images.

Abstract: When performing inter-layer prediction, the present method and apparatus make predictive inter-layer determinations, such as from the LDR layer to the HDR layer, based on pixels used in the LDR layer for intra prediction of the LDR block using an intra LDR mode and also based on the homologous pixels in the HDR layer for the intermediate intra prediction block using the same intra LDR mode. By using these bases, it is possible to estimate an inverse tone mapping function and then apply this estimated function to the LDR block in order to determine the inter-layer HDR prediction block.

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 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 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: 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.

Abstract: To encode High Dynamic Range (HDR) images, the HDR images can be converted to Low Dynamic Range (LDR) images through tone mapping operation, and the LDR images can be encoded with an LDR encoder. The present principles formulates a rate distortion minimization problem when designing the tone mapping curve. In particular, the tone mapping curve is formulated as a function of the probability distribution function of the HDR images to be encoded and a Lagrangian multiplier that depends on encoding parameters. At the decoder, based on the parameters indicative of the tone mapping function, an inverse tone mapping function can be derived to reconstruct HDR images from decoded LDR images.

Abstract: The present principles provide a method and an encoder for encoding an image frame. The method includes generating, with a processor, for each block in the image frame a prediction block based on at least a prediction method; generating a scaling factor and an offset for adjusting the prediction block; and transforming the prediction block into an adjusted prediction block based on the scaling factor and the offset. The encoder includes a processor configured to, for each block in the image frame, generate a prediction block based on at least a prediction method and generate a scaling factor and an offset for adjusting the prediction block and to transform the prediction block into an adjusted prediction block based on the scaling factor and the offset. The scaling factor and offset minimize error between the block and the adjusted prediction block.

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.