Backlight Color Shift Compensation for Displays
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Solution Overview
Problem
Electronic displays experience visible image artifacts such as discolorations due to a color shift caused by changes in backlight brightness, particularly when different color component LEDs respond at different rates.
Innovation Solution
A color shift compensation system that adjusts image data by increasing red pixel values and/or decreasing green/blue pixel values to maintain a balanced ratio of red, green, and blue light emission, and also employs backlight modulation techniques such as staged brightness increases and delayed activation to reduce the disparity between LED outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the backlight brightness is increased, then the overall luminance output is improved, but the color balance deteriorates due to different LED response rates
Solution Approach 1:
The system performs preliminary compensation by adjusting the image data for red, green, and blue pixels before the backlight brightness change occurs. When a brightness increase is detected, the system preemptively modifies the pixel values to counteract the expected color shift, ensuring that the color balance is maintained throughout the transition.
Solution Approach 2:
The system dynamically changes the parameters of the image data (pixel values for red, green, and blue channels) based on the detected backlight brightness changes. By adjusting these parameters in real-time, the system compensates for the color shift caused by different LED response rates while maintaining overall brightness improvement.
2Illumination intensity
If the red LED brightness is increased, then the red light output is improved, but the response time deteriorates due to slower red LED response rate
Solution Approach 1:
The system applies preliminary compensation to the red pixel values in the image data before the backlight brightness change occurs. This preemptive adjustment accounts for the slower response rate of red LEDs, ensuring that the red light output reaches the desired level without causing visible color shifts during the transition.
Solution Approach 2:
The system applies an opposite compensation to the red pixel values to counteract the expected delayed response. By increasing the red pixel values in advance, the system compensates for the slower red LED response, ensuring that the final red light output matches the intended color balance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces or eliminates visible image artifacts associated with backlight color shifts, ensuring that the total amount and ratio of color component lights emitted remain consistent with the intended image data, even as backlight brightness changes.
Implementation Method 1
The backlight may include multiple light emitting diodes (LEDs) (e.g., a red LED, a green LED, and a blue LED) to generate the backlight
Implementation Method 2
such as in KSF phosphor LEDs
Data Source
AI summary
A device may include an electronic display having a backlight that generates light and multiple display pixels that modulate the amount of generated light emitted from the electronic display based on compensated image data. The backlight may include multiple illuminators that generate the light, and a first color component illuminator may have a slower response rate than a second color component illuminator. The device may also include image processing circuitry that generates the compensated image data by compensating input image data for a color shift associated with a change in brightness of the backlight and the slower response rate of the first color component illuminator. The input image data may be compensated by increasing first color component pixel values of the input image data relative to second color component pixel values of the input image data, and the compensated image data may be output to the electronic display.