Pixel Luminosity Correction for Mura Defects in VR Displays
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Solution Overview
Problem
Display technologies like LCDs and OLEDs suffer from pixel-by-pixel energy emission variations, known as 'mura defects,' which cause artifacts in constant color regions and smooth gradients, particularly noticeable in head-mounted displays, and existing correction techniques are limited in effectiveness.
Innovation Solution
A method involving accurate energy estimation for each sub-pixel, computation of global and per-pixel correction factors using iterative and non-iterative approaches, and real-time imagery processing to reduce visual artifacts, employing advanced imaging techniques and correction models to account for geometric lens eccentricities and camera-sub-pixel alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If pixel-by-pixel energy emission variations are measured and corrected, then visual artifacts are reduced, but device complexity increases
Solution Approach 1:
The system performs preliminary measurement of pixel energy emission variations during display manufacturing or calibration, storing correction factors in advance. This allows the correction data to be prepared beforehand and applied during normal operation without adding real-time processing complexity
Solution Approach 2:
The patent introduces an intermediary correction layer that sits between the display output and the viewer's perception. This correction layer processes the image data using pre-computed factors, acting as a mediator that reduces mura artifacts without requiring complex hardware modifications to the display itself
2Measurement precision
If accurate energy estimation for each sub-pixel is performed, then measurement precision improves, but difficulty of detecting and measuring increases
Solution Approach 1:
The measurement process is segmented into discrete steps: capturing multiple images at different color temperatures, separating sub-pixel responses through mathematical decomposition, and computing correction factors for each sub-pixel type. This segmentation makes the complex measurement task manageable and accurate
Solution Approach 2:
The system captures images at more color temperatures than strictly necessary (excessive action) to ensure accurate separation of sub-pixel responses. By using more measurement data points than the minimum required, the system achieves higher precision in energy estimation
Data Source
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).