Gamma Prediction for Displays Using PCA Coefficients

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Solution Overview

Problem

Conventional methods for characterizing gamma characteristics in displays with dynamic behavior and average power level dependency are limited, as they require multiple measurements for different power levels, making general gamma correction difficult and ineffective for dynamic contrast and image quality enhancement.

Innovation Solution

A method and system that predict gamma characteristics by measuring gamma curves at various average power levels, using Principal Component Analysis to extract basis vectors and coefficients, allowing for accurate gamma correction and adaptation to changing power levels through interpolation and extrapolation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If gamma characteristics are measured for multiple APL settings, then measurement precision is improved, but device complexity and measurement time increase

Engineering Contradiction:
Improvegamma measurement precisionVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent performs gamma measurements at multiple APL settings (10%, 30%, 50%, 70%, 90%) during the calibration phase before actual display operation. These preliminary measurements establish a comprehensive gamma profile that captures dynamic behavior across different power levels, enabling accurate gamma correction without requiring real-time measurements during content playback.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a reference gamma profile by measuring the display at multiple APL settings and stores this as reference data. During operation, the system copies and applies the appropriate reference gamma characteristics based on the current APL detection, avoiding the need to perform complete multi-APL measurements for every content piece while maintaining measurement precision.

Inventive Principle:
Principle #26Copying

2Ease of operation

If gamma correction is applied for fixed APL, then ease of operation is improved, but adaptability to dynamic power levels deteriorates

Engineering Contradiction:
Improvegamma correction simplicityVSAvoidadaptability to dynamic APL
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic gamma correction by continuously detecting the current APL during display operation and automatically selecting or adjusting the gamma characteristics to match the detected power level. This dynamic adaptation ensures accurate gamma correction across varying content brightness levels without requiring manual intervention or complex user configuration.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates APL detection that continuously monitors the actual power level of displayed content and provides feedback to the gamma correction mechanism. This feedback loop enables the display to automatically adjust its gamma characteristics in real-time based on the detected APL, maintaining image quality consistency across different content types and brightness levels.

Inventive Principle:
Principle #23Feedback

3Reliability

If multiple gamma measurements are performed for different APLs, then reliability of gamma correction is improved, but loss of time increases

Engineering Contradiction:
Improvegamma correction reliabilityVSAvoidmeasurement and calibration time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs comprehensive multi-APL gamma measurements during the initial calibration phase, storing the results as reference data. This preliminary action ensures that reliable gamma correction data is available before actual display operation begins, eliminating the need for time-consuming measurements during content playback while maintaining correction reliability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system copies pre-measured gamma characteristics from the reference profile corresponding to the detected APL level and applies them during operation. This copying approach maintains the reliability of gamma correction based on actual measurements while significantly reducing the time required during content playback, as no new measurements are performed in real-time.

Inventive Principle:
Principle #26Copying

Data Source

PatentEP2153639B1Method and system for prediction of gamma characteristics for a display
Publication Date: 2020.09.23 INTERDIGITAL MADISON PATENT HLDG
  • EP2153639B1 patent drawingFigure 1~6
  • EP2153639B1 patent drawingFigure 2
  • EP2153639B1 patent drawingFigure 4

AI summary

A method and system for gamma adjustment for average power level dependency displays includes applying gamma controlled functions over a range of values at a plurality of average power levels (APLs) for a display. The gamma controlled functions include coefficients for reconstruction of the gamma controlled functions. Upon a change to an APL, interpolation is performed between the coefficients to predict a new gamma controlled function for the new APL.