Thomson Licensing

Interdigital Vc Holdings, Inc.

Ronan Boitard

Dominique Thoreau

Kadi Bouatouch

Yannick Olivier

Christine Guillemot

Mikael Le Pendu

Remi Cozot

Philippe Guillotel

Christel Chamaret

Tania Pouli

Catherine Serre

Laurent Cauvin

Rémi Cozot

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.

Method and apparatus for encoding and decoding HDR images

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.

Method and device for processing images

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.

Method and device for quantising the floating value of a pixel in an image

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

Method for inverse tone mapping of a sequence of images

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.

Method and device for selecting an image dynamic range conversion operator

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.

Method and device for converting an image sequence whose luminance values belong to a high dynamic range

The invention relates to a method for processing a video sequence formed by at least two video images, said method comprising:

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Belz, France

Ronan Boitard