Luminance Modulator for Adaptive Gamma Correction
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Solution Overview
Problem
Existing image processing technologies for liquid crystal display devices with backlight control struggle to improve visibility-wise luminance adaptively while reducing power consumption, as they primarily focus on compensating visibility degradation through backlight control, which restricts the effectiveness of luminance enhancement.
Innovation Solution
An image processing device that includes a luminance modulator, a backlight control gain adjustment unit, a peak value detector, and a histogram detector, which calculates and adjusts the luminance values of video signals based on peak values and frequency distributions to perform peak ACL control and adaptive gamma correction, enhancing visibility and contrast according to picture patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If backlight luminance is reduced to reduce power consumption, then power consumption is reduced, but visibility of low luminance gradation deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gamma value based on backlight control conditions. When backlight luminance is reduced, the system changes the gamma parameter to a smaller value, which transforms the video signal to compensate for the reduced backlight, thereby maintaining visibility of low luminance gradation while enabling power consumption reduction through backlight dimming.
Solution Approach 2:
The patent implements preliminary anti-action by performing gamma correction with a smaller gamma value before the backlight luminance is reduced. This preliminary signal processing compensates in advance for the expected visibility degradation, ensuring that when the backlight is dimmed to save power, the low luminance gradation remains visible through the pre-applied gamma transformation.
2Illumination intensity
If gamma correction is performed to improve visibility-wise luminance, then visibility is improved, but power consumption increases due to higher backlight luminance requirement
Solution Approach 1:
The patent inverts the conventional approach by using a smaller gamma value instead of a larger gamma value for gamma correction. Conventionally, larger gamma values are used to improve visibility, but this increases required backlight luminance and power consumption. The patent reverses this logic by applying smaller gamma values that achieve visibility improvement while requiring lower backlight luminance, thereby reducing power consumption.
3Reliability
If fixed gamma correction is applied, then gamma characteristic compensation is achieved, but adaptability to different picture patterns is insufficient
Solution Approach 1:
The patent applies dynamics by making the gamma value variable rather than fixed. The system dynamically determines the gamma value based on picture pattern analysis, specifically using the standard deviation of luminance values to assess picture complexity. For complex pictures with high standard deviation, a smaller gamma value is applied, while for simple pictures, a larger gamma value or no correction is applied, thereby achieving both reliable gamma compensation and high adaptability to different picture patterns.
Data Source
AI summary
An image processing device includes a luminance modulator operable to receive a video input signal and operable to calculate a video output signal to be supplied to a display panel, a peak value detector operable to calculate a peak value as a maximum luminance in a prescribed region of the video input signal, a histogram detector operable to calculate frequency distribution about a luminance value of the video input signal in the prescribed region, a peak Automatic contrast level (ACL) control gain calculation unit operable to calculate a peak ACL control gain with which luminance of each pixel of the video input signal is amplified, based on the ratio of the peak value to a maximum possible value of the video output signal, and a pattern-adaptive gamma characteristic calculation unit operable to calculate a luminance modulation gain.