Chromatic Correction Block for OLED Color Accuracy
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Solution Overview
Problem
Electronic displays, particularly OLEDs, face challenges in maintaining color accuracy and contrast under extreme ambient light conditions, with rod intrusion in low-light conditions causing color loss and external light interference in bright conditions reducing color gamut.
Innovation Solution
A chromatic correction block is implemented in electronic devices to compensate for perceived chromatic deviations by converting image data between color spaces, applying adjustments based on look-up tables, and restoring luminance and chrominance levels to maintain color consistency across varying light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If display pixels emit light at standard luminance levels, then energy consumption is optimized and display longevity is extended, but color accuracy and contrast are degraded in extreme ambient light conditions
Solution Approach 1:
The system performs preliminary chromatic correction by converting image data to a different color space (e.g., from sRGB to a perceptually uniform color space like CIE L*a*b* or CIE LCH) before display. This pre-processing adjusts the luminance and chrominance values to compensate for expected perception deviations in extreme light conditions, allowing the display to maintain color accuracy without increasing physical luminance output.
Solution Approach 2:
The system changes the color space parameters used for image representation. By transforming image data from a standard color space to a perceptually uniform color space and back, the system modifies the parameter values (luminance, chroma, hue) in a way that compensates for rod intrusion and external light interference effects, maintaining perceived color accuracy at standard display luminance levels.
2Reliability
If display luminance is increased to compensate for color loss in low-light conditions, then color perception improves, but power consumption increases and display longevity decreases
Solution Approach 1:
The system applies chromatic correction transformations to image data before display, pre-compensating for the rod intrusion effect that occurs in low-light conditions. This allows the display to maintain accurate color perception without increasing luminance output, thereby preserving OLED lifespan while improving color perception in dark environments.
Solution Approach 2:
The system transforms image data into a perceptually uniform color space where chromaticity parameters are adjusted to counteract the desaturation and hue shifts caused by rod intrusion. This parameter transformation enables accurate color perception at low luminance levels without requiring increased display brightness, thus protecting display longevity.
3Use of energy by moving object
If display luminance is decreased to save energy in bright ambient light conditions, then power consumption is reduced, but color gamut and contrast are further compressed by external light interference
Solution Approach 1:
The system performs chromatic correction by transforming image data into a perceptually uniform color space before display. This pre-processing compensates for the compression of color gamut caused by external light interference, allowing the display to maintain accurate color representation at reduced luminance levels, thus saving power while preserving color gamut in bright ambient conditions.
Solution Approach 2:
The system changes the color space parameters to account for external light interference effects. By transforming to a perceptually uniform color space and adjusting chromaticity values, the system compensates for the narrowing of perceived color gamut in bright light conditions, maintaining color accuracy without increasing display luminance or power consumption.
4Reliability
If chromatic correction is applied to maintain color accuracy in extreme light conditions, then perceived color consistency improves, but image processing complexity and computational load increase
Solution Approach 1:
The system applies chromatic correction by converting image data to a perceptually uniform color space using pre-computed transformation matrices. This preliminary processing step, performed before display output, establishes the corrected color values that compensate for extreme light conditions, achieving color consistency through a standardized, efficient color space transformation approach.
Data Source
AI summary
Systems and techniques described herein may correct for chromatic deviations due to ambient dependent color perception in low-light conditions and/or bright-light conditions. Processing circuitry may determine a first and a second strength parameter based on an ambient brightness value, an intended display brightness value, one or more vectors, and a two-dimensional look up table. If the first strength parameter is greater than zero, then the processing circuitry may apply chromatic corrections based on luminance and chrominance compensation functions in an opponent color space. For example, per-pixel gains may be determined based on global curves and applied as a function of pixel value (e.g., luminance component). If the first strength parameter is less than zero and the second strength parameter is greater than zero, the processing circuitry may determine chromatic corrections based on a three-dimensional lookup table that may be programmable based on a strength parameter and/or a gain value.