# US 11,910,025 B1 · Signal reshaping for high dynamic range signals

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- Number: US 11,910,025 B1
- Document ID: US11910025B1
- Status: Granted
- Kind: B1
- Application number: 18/385,724
- Filed: 2023-10-31
- Published: 2024-02-29
- Granted: 2024-02-20
- Earliest claimed: 2015-08-04
- Assignees: Dolby Laboratories Licensing Corporation
- Applicants: Dolby Laboratories Licensing Corporation
- Inventors: Robin Atkins; Peng Yin; Taoran Lu; Jaclyn Anne Pytlarz
- Web page: https://patentgrep.com/patent/US11910025B1

## CPC

- H04N 19/87: involving scene cut or scene change detection in combination with video compression
- G09G 5/02: characterised by the way in which colour is displayed {(details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607)}
- H04N 1/6058: {Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut}
- H04N 9/643: {Hue control means, e.g. flesh tone control}
- H04N 9/67: for matrixing (camera processing pipelines for matrixing of colour signals H04N23/85)
- H04N 9/68: for controlling the amplitude of colour signals, e.g. automatic chroma control circuits (H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86)
- H04N 9/77: Circuits for processing the brightness signal and the chrominance signal relative to each other, e.g. adjusting the phase of the brightness signal relative to the colour signal, correcting differential gain or differential phase (circuits for matrixing H04N9/67)
- H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence)
- H04N 19/85: using pre-processing or post-processing specially adapted for video compression
- H04N 19/98: Adaptive-dynamic-range coding [ADRC]
- G09G 2320/0276: for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
- G09G 2320/06: Adjustment of display parameters
- G09G 2340/06: Colour space transformation
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## Abstract

In a method to improve backwards compatibility when decoding high-dynamic range images coded in a wide color gamut (WCG) space which may not be compatible with legacy color spaces, hue and/or saturation values of images in an image database are computed for both a legacy color space (say, YCbCr-gamma) and a preferred WCG color space (say, IPT-PQ). Based on a cost function, a reshaped color space is computed so that the distance between the hue values in the legacy color space and rotated hue values in the preferred color space is minimized HDR images are coded in the reshaped color space. Legacy devices can still decode standard dynamic range images assuming they are coded in the legacy color space, while updated devices can use color reshaping information to decode HDR images in the preferred color space at full dynamic range.

## Claims

### Claim 1

A method for processing images, the method comprising:
receiving an input picture in a linear RGB color space, wherein RGB pixel values are normalized to be between 0 and 1;
generating a first picture in an LMS color space by applying an RGB to LMS color transformation to the input picture, wherein the RGB to LMS transformation comprises
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applying a non-linear function to each color component of the first picture to generate color components of a second picture in a non-linear LMS color space, wherein the non-linear function comprises one of: an inverse of an SMPTE ST 2084 electro-optical transfer function or a Hybrid Log-Gamma (HLG) function; and
generating an output picture in an ICtCp color space by applying a color transformation matrix to the color components of the second picture, wherein the color transformation matrix comprises:
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4096.

### Claim 2 (depends on 1)

The method of claim 1, wherein the linear RGB color space is a BT.2020 RGB color space.