Display Pixel Correction for Luminosity and Chrominance Mura

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Solution Overview

Problem

Display technologies exhibit pixel-by-pixel luminosity and colorimetric variations, known as 'mura defects', which cause visual artifacts, especially noticeable in regions of constant color and smooth gradients, particularly in head-mounted displays.

Innovation Solution

A method and apparatus for reducing these artifacts by accurately estimating energy emission for each sub-pixel, applying global and per-pixel correction factors, and processing imagery in real-time to minimize these variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If display technologies are used to provide visual output, then information display capability is improved, but pixel-by-pixel luminosity and colorimetric variations (mura defects) cause visual artifacts that deteriorate image quality

Engineering Contradiction:
Improveimage qualityVSAvoidvisual artifacts from mura defects
Core Design Contradiction:
Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary characterization of the display panel during manufacturing or initialization, measuring the actual luminosity and colorimetric response of each pixel or pixel group. These measurements are stored as correction data that will be applied during normal operation to compensate for the identified variations and prevent visual artifacts.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of applying uniform correction across the entire display, the system divides the panel into multiple pixel groups or regions and applies localized correction factors to each region based on its specific characteristics. This allows precise compensation for local variations in luminosity and color response while maintaining overall display performance.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If correction data is collected and stored for each pixel group, then manufacturing precision is improved, but device complexity increases due to additional data storage and processing requirements

Engineering Contradiction:
Improvepixel response uniformityVSAvoidcorrection data storage and processing system
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The display panel is divided into multiple pixel groups, where each group contains multiple pixels that share common correction characteristics. This segmentation reduces the total number of correction parameters needed compared to individual pixel correction, while still achieving effective compensation for local variations. The correction data structure is organized hierarchically to facilitate efficient storage and processing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system transforms the complex multi-dimensional pixel response characteristics into a simplified set of correction parameters that can be efficiently stored and applied. By characterizing each pixel group in terms of key parameters (such as average luminosity, color coordinates, and gamma response), the system reduces data complexity while maintaining correction effectiveness.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3338274B1Systems and methods for detection and/or correction of pixel luminosity and/or chrominance response variation in displays
Publication Date: 2025.07.30 VALVE CORPORATION
  • EP3338274B1 patent drawingFigure 1
  • EP3338274B1 patent drawingFigure 2A~2E
  • EP3338274B1 patent drawingFigure 3

AI summary

Methods and systems are disclosed for measuring pixel-by-pixel luminosity and/or chrominance variations on a display, encoding and/or storing the measurements as a set of global and/or pixel-by-pixel correction factors, and/or digitally manipulating imagery with the inverse effect as the measured variations, such that the appearance of visual artifacts caused by the variations is reduced. These methods and systems may be used, for example, as part of the production process for virtual reality headsets, as well as in other applications that make high-fidelity use of displays exhibiting such artifacts (e.g., cell phones, watches, augmented reality displays, and the like).