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: A method of producing at least one output image signal representing, at least, a plurality of output luminance values in an output range of luminance values is disclosed. The method involves: identifying a mapping function based at least in part on a perceptually scaled distribution of a plurality of input luminance values in an input range of luminance values different from the output range of luminance values; transforming the plurality of input luminance values into respective perceptually scaled output luminance values according to the mapping function; transforming the perceptually scaled output luminance values into respective ones of the plurality of output luminance values; and producing the at least one output signal representing, at least, the plurality of output luminance values. Computer-readable media and apparatuses are also disclosed.

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: A method of producing at least one output image signal representing, at least, a plurality of output luminance values in an output range of luminance values is disclosed. The method involves: identifying a mapping function based at least in part on a perceptually scaled distribution of a plurality of input luminance values in an input range of luminance values different from the output range of luminance values; transforming the plurality of input luminance values into respective perceptually scaled output luminance values according to the mapping function; transforming the perceptually scaled output luminance values into respective ones of the plurality of output luminance values; and producing the at least one output signal representing, at least, the plurality of output luminance values. Computer-readable media and apparatuses are also disclosed.

Abstract: A method and device for processing LDR images of a video sequence to improve image quality. The method comprises temporally decomposing successive HDR frames of a video sequence and the corresponding LDR frames and performing a comparison between the HDR and LDR frequency sub-bands. A current LDR image can then be modified on the basis of a comparison between the frequency sub-bands.

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 described for inverse tone mapping the luminance (Yt(p)) of each pixel (p) of at least one image (It) of this sequence into an expanded luminance Ytexp(p)=Yt(p)Et(p). Ytenh(p), wherein Et(p) is an expansion exponent value extracted from an expansion exponent map built from low pass motion-compensated temporal filtering of said image (It) and wherein Ytenh(p) is a luminance-enhancement value extracted from a luminance-enhancement map built from high pass motion-compensated temporal filtering of said image (It).

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.

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 characterized 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 and device for processing LDR images of a video sequence to improve image quality. The method comprises temporally decomposing successive HDR frames of a video sequence and the corresponding LDR frames and performing a comparison between the HDR and LDR frequency sub-bands. A current LDR image can then be modified on the basis of a comparison between the frequency sub-bands.

Abstract: A method is described for inverse tone mapping the luminance (Yt(p)) of each pixel (p) of at least one image (It) of this sequence into an expanded luminance Ytexp(p)=Yt(p)Et(p). Ytenh(p), wherein Et(p) is an expansion exponent value extracted from an expansion exponent map built from low pass motion-compensated temporal filtering of said image (It) and wherein Ytenh(p) is a luminance-enhancement value extracted from a luminance-enhancement map built from high pass motion-compensated temporal filtering of said image (It).

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: 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 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: 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: 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.