Rational Function Opto-Electronic Transfer for HDR Video Accuracy

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Solution Overview

Problem

Existing HDR video coding technologies face challenges in accurately processing media data due to reliance on display device brightness and ambient light, leading to low accuracy and increased complexity, particularly with logarithmic operations in Hybrid Log Gamma (HLG) conversion functions.

Innovation Solution

The method involves determining an opto-electronic transfer control parameter based on the optical signal intensity of sampling points, using a rational function to perform opto-electronic transfer, and encoding this parameter into a bitstream to adaptively adjust conversion curves for different light intensity regions, thereby improving accuracy and reducing computational complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If HLG transfer function is used for HDR video coding, then backward compatibility with SDR devices is achieved, but processing complexity increases due to logarithmic operations

Engineering Contradiction:
Improvebackward compatibilityVSAvoidprocessing complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the mathematical function type from logarithmic (HLG) to rational function, altering the transfer function parameters to achieve similar HDR-SDR compatibility without the computational complexity of logarithmic operations. The rational function uses simpler arithmetic operations while maintaining the essential tone mapping characteristics.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the mathematical computation mechanism by replacing complex logarithmic calculations with simpler rational function calculations, reducing the computational burden while achieving the same functional goal of HDR to SDR tone mapping for backward compatibility.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If HLG transfer function is used for HDR video coding, then tone mapping is achieved, but accuracy decreases due to reliance on display device brightness and ambient light

Engineering Contradiction:
Improvetone mapping accuracyVSAvoidenvironmental adaptability
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent extracts and removes the dependency on environmental factors (display device brightness and ambient light) from the tone mapping process. By using a rational function that does not require these external parameters, the method achieves more consistent and accurate tone mapping independent of viewing conditions.

Inventive Principle:
Principle #2Taking out (Extraction)

3Illumination intensity

If floating-point data is used for HDR storage, then brightness range is expanded, but storage space and bandwidth increase

Engineering Contradiction:
Improvebrightness rangeVSAvoidstorage space
Core Design Contradiction:
Illumination intensityVSQuantity of substance

Solution Approach 1:

The patent applies partial action by performing tone mapping only when necessary (during HDR to SDR conversion) rather than maintaining full HDR precision throughout the entire processing chain. This allows selective use of computational resources and data precision, reducing storage requirements while preserving HDR capabilities where needed.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3461118B1Media data processing method and apparatus
Publication Date: 2024.01.17 ZTE CORP
  • EP3461118B1 patent drawingFigure 1~2
  • EP3461118B1 patent drawingFigure 3~4
  • EP3461118B1 patent drawingFigure 5

AI summary

Provided in an embodiment of the present invention are a media data processing method, an apparatus and a system. The method comprises: obtaining an optical signal of a sampling point by a collection device at the source end in an acquisition of media data; according to an opto-electronic transfer control parameter, performing opto-electronic transfer for the optical signal of the sampling point to obtain a transferred electrical signal, wherein the opto-electronic transfer control parameter is determined on the basis of an optical signal intensity of the optical signal of the sampling point; and encoding the electrical signal and opto-electronic transfer control parameter to obtain a bitstream. According to the embodiment of the present invention, the problem of the lower accuracy in the media data processing is solved, thereby obtaining the effect of improving the accuracy in the media data processing.