Liquid Crystal Display Tone Mapping Control for Black Floating Reduction
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Solution Overview
Problem
Existing video display devices, such as those employing local dimming, fail to sufficiently reduce black floating in dark sections and improve contrast ratios due to limitations in signal compensation gain and circuit scale.
Innovation Solution
A control device for liquid crystal display devices that obtains a first video signal, determines a backlight value based on its luminance characteristic, performs tone mapping, and generates a control signal for local dimming, allowing for adjusted luminance and reduced black floating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If local dimming control is performed on the backlight, then contrast ratio is improved, but black floating in dark sections cannot be sufficiently reduced
Solution Approach 1:
The patent applies tone mapping processing to the video signal before local dimming control is executed. This preliminary adjustment of luminance characteristics modifies the video signal based on the backlight value and displayable peak luminance, preparing the signal in advance to work synergistically with local dimming. The tone-mapped signal is then used in generating the local dimming control signal, creating a coordinated approach that effectively reduces black floating while maintaining contrast improvement.
2Object-affected harmful factors
If signal compensation gain is increased to reduce black floating, then black floating is reduced, but circuit scale increases
Solution Approach 1:
The patent changes the luminance parameters of the video signal through tone mapping before local dimming processing. By adjusting the luminance characteristics of the input video signal to match the backlight value and peak luminance capabilities, the system achieves effective black floating reduction through parameter transformation rather than through high-gain signal compensation circuits. This approach reduces black floating while avoiding the need for large-scale compensation circuits.
Data Source
AI summary
A control device that controls a liquid crystal display device, the control device includes: an obtainer that obtains a first video signal; a determiner that determines a first backlight value as a reference luminance of a backlight of the liquid crystal display device, using a first luminance characteristic of the first video signal; a tone map processor that performs tone mapping on the first video signal based on the first backlight value and a peak luminance displayable by the liquid crystal display device, and outputs a second video signal obtained through the tone mapping; and a generator that generates a control signal for local dimming control on the liquid crystal display device based on the first backlight value and the second video signal, and outputs the control signal to the liquid crystal display device.