Interdigital Vc Holdings, Inc.

Interdigital Ce Patent Holdings, Sas

Interdigital Patent Holdings, Inc.

Marie-Jean Colaitis

David Touze

Pierre Andrivon

Jurgen Stauder

Patrick Lopez

Angelo Mazzante

Philippe Bordes

Fabrice Urban

Yannick Olivier

Cedric Thebault

Patrick Morvan

Tania Pouli

Joan Llach Pinsach

Catherine Serre

Laurent Cauvin

Francois Cellier

Nicolas Caramelli

A method comprising obtaining a current RGB image; classifying colors of pixels of the current RGB image in a plurality of classes; for each color class, determining data representative of said color class, comprising a dominant luminance value representative of a luminance at which a color in said class is predominant and determining from said data representative of said color class a value representative of a gain of chrominance representative of a margin for increasing a chrominance component in said color class; and, encoding the dominant luminance value and the value representative of the gain corresponding to each class as metadata representative of a Saturation Gain Function in a bitstream, said function defining a color correction to apply to a pixel in function of a luminance of said pixel.

Chroma boost on SDR and HDR display adapted signals for SL-HDRx systems

A device applies a pre-function w=P(x) to an input signal x to obtain a first result w and applies a LUT to the first result w, wherein the LUT represents a main function ƒ(w) defined for a second grid of values Gw such that the pre-function P(x) is piecewise defined on a first grid Gx of signal values, where Gw=P(Gx). The device can further obtain the pre-function P(x), piecewise defined on the first grid Gx of the signal x and calculate the LUT with the second grid Gw=P(Gx). The piecewise pre-function P(x) can be obtained from a second pre-function Q(x) by applying Q(x) to signal values x to calculate the second grid Gw=Q(Gx) and defining the pre-function P(x) piecewise on the first grid Gx by linear interpolation of the values of the second grid Gw such that P(Gx)=Q(Gx).

Device and method for applying a look-up table

A system and method is provided for generating a tone mapping function to reduce dynamic range of a first image to produce a second image. A luma signal and a plurality of chroma components are determined and a gamut color correction is then performed. An adaptive function is generated by comparing the luma signal and at least one chroma component of the first and second image.

Saturation control for high-dynamic range reconstruction

Encoding can involve correcting chroma components representing the chroma of an input image according to a first component representing a mapping of the luminance component of said input image used for reducing or increasing the dynamic range of said luminance component, and a reconstructed component representing an inverse mapping of said first component. At least one correction factor according to said at least one scaled chroma components can also be obtained and transmitted. Decoding can involve scaled chroma components being obtained by multiplying chroma components of an image by at least one corrected chroma correction function depending on said at least one correction factor. Components of a reconstructed image can then be derived as a function of said scaled chroma components and a corrected matrix that depends on an inverse of a theoretical color space matrix conversion and said at least one correction factor.

Method and device for chroma correction of a high-dynamic-range image

Different implementations are described, particularly implementations for processing a medium dynamic range video signal are presented. In a method for processing such a video signal a medium dynamic range video signal and associated metadata are received, wherein the metadata include data representative of a peak luminance value of the medium dynamic range video signal. In addition, data representative of a peak luminance value of a presentation display are received. It is determined whether the peak luminance value of the medium dynamic range video signal is greater or lower than the peak luminance value of the presentation display. A processor is configured based on the determination, wherein the processor has a first mode to reconstruct a high dynamic range video signal based on a received standard dynamic range video signal and associated metadata, and a second mode to optimize a received high dynamic range video signal for the rendering device. The medium dynamic range video signal is processed by the processor in the first mode if the peak luminance value of the medium dynamic range video signal is smaller than the peak luminance value of the presentation display and in the second mode if the peak luminance value of the medium dynamic range video signal is greater than the peak luminance value of the presentation display.

Method and apparatus for processing a medium dynamic range video signal in SL-HDR2 format

A method for decoding an image enables to preserve artistic intent at the final rendering stage by adjusting the image to luminance characteristics of the content and of the presentation display that will display the image. Values representative of luminance of both the image and the display device are obtained. Parameters of a display adaptation function are adjusted according to these values and the adjusted display adaptation function is used to decode the image. In at least one embodiment, the adjusted display adaptation function relates to a tone mapping function. Corresponding apparatus implementing the method is also described.

Decoding an image

The present embodiments obtain chroma components representative of the chroma components of an output image from color components representative of an input image, and if a value of a pixel in at least one of said chroma components exceeds a given value, modify the value of said pixel in at least one of said color components in such a way that the value of said pixel in said at least one of said chroma components is lower than or equals to said given value.

Method and apparatus for encoding an image

Described are methods and devices for applying a color gamut mapping process on a first image to generate a second image, where the content of the first and second images is similar but the respective color spaces of the first and second images are different. The color gamut mapping process may be controlled using a color gamut mapping mode obtained from a bitstream where the color gamut mapping mode belongs to a set comprising at least two preset modes and an explicit parameters mode. If the obtained color gamut mapping mode is the explicit parameters mode and the color gamut mapping process is not enabled for the explicit parameters mode, the color gamut mapping process may be controlled by a substitute color gamut mapping mode determined from additional data.

Method and device for generating a second image from a first image

The present embodiments relate to a method and apparatus comprising: &#x2014;deriving chroma components (I) of a third image by correcting chroma components (II) of a second image according to a luma component of said second image and a reconstructed component obtained by applying a mapping function to said luma component (III) of said second image, said chroma components (II) of the second image being obtained by applying a conversion matrix to components (IV) of a first image; and &#x2014;adapting coefficients of the conversion matrix which are relative to a chroma component of said third image independently of coefficients of the conversion matrix which are relative to another chroma component of said third image to ensure that there is no clipping on chroma components of the third image.

Method and apparatus for colour correction during HDR to SDR conversion

A medium dynamic range video signal and associated metadata are received, wherein the metadata include data representative of a peak luminance value of the signal. The medium dynamic range video signal is processed in a first mode to reconstruct a high dynamic range video signal based on a received standard dynamic range video signal and associated metadata if the peak luminance value of the medium dynamic range video signal is smaller than the peak luminance value of a presentation display, and in a second mode to optimize a received high dynamic range video signal for a rendering device if the peak luminance value of the medium dynamic range video signal is greater than the peak luminance value of the presentation display.

The present principles relate to a method and device for gamut mapping from a first color gamut towards a second color gamut. The method comprises, in a plane of constant hue, obtaining a target lightness for a color on the boundary of first gamut with maximum chroma, called first cusp color; and lightness mapping of the color from the first color gamut towards the second color gamut wherein the lightness mapped color is calculated from a parabolic function applied to the color, the parabolic function mapping the first cusp color to a color having the target lightness. According to a particular characteristic, a preserved chroma is also obtained; and in case the chroma of the color is lower than or equal to the preserved chroma, the lightness mapped color is the color, and in case the chroma of the color is higher than the preserved chroma, the lightness mapped color is calculated from the parabolic function applied to the color.

Method and device for color gamut mapping

A method for color mapping a video signal into a mapped video signal responsive to at least one color mapping function is disclosed. To this aim, at least one black point offset is determined responsive to a color encoding system of the video signal and to a color encoding system of the mapped video signal. The at least one black point offset and the at least one color mapping function are then applied on the video signal to obtain the mapped video signal.

Method for color mapping a video signal and method of encoding a video signal and corresponding devices

The module () comprises: &#x2014;a low pass filter for low pass filtering luminance component of the image, &#x2014;a first look up table () storing precomputed values of a first expansion function of only low pass filtered luminance values, &#x2014;a second look up table () storing precomputed values of a second expansion function of only luminance values, &#x2014;a processor () configured to multiply an output of the second look up table corresponding to an input luminance value of a color to expand by an output of said first look up table corresponding to an input low pass filtered luminance value associated with said input luminance value.

Low cost color expansion module for expanding colors of an image

Source colors are mapped within a mapping segment starting at a preserved gamut boundary color (P) and ending at a target gamut boundary color (I) of the chromaticity plane, corresponding, in a linear 3D color space, to an intersection of the target color gamut (TCG) with a plane of constant luminance and with a mapping plane (MKO) comprising said source color (M), a black point (K) and a white point (O).

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Cesson-Sevigne, France

Marie-Jean Colaitis