Image Processing Apparatus Luminance Correction for Display Contrast
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Solution Overview
Problem
Existing image display devices, such as liquid crystal display devices, face challenges in achieving ideal modulation characteristics, leading to reduced contrast and increased power consumption due to light leakage, especially when displaying black, and color changes in low luminance conditions caused by quantization errors.
Innovation Solution
An image processing apparatus that calculates and corrects luminance levels for multiple colors, applies gradation conversion functions, and generates luminance control signals to modulate light sources, ensuring reduced differences in luminance and approaching an achromatic color at low luminance levels to prevent color changes and enhance contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If light source luminance is lowered to reduce power consumption, then power consumption is reduced, but color of the displayed image changes due to quantization error
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the luminance conversion coefficients based on the detected luminance level. When luminance is low, the system changes the conversion parameters to compensate for quantization errors, thereby maintaining color accuracy while reducing power consumption. This is implemented through the luminance conversion unit that uses different conversion coefficients depending on the luminance range.
2Illumination intensity
If light modulation device is used to display black, then contrast can be improved, but light leakage causes reduction in contrast
Solution Approach 1:
The patent extracts and compensates for the harmful light leakage effect by detecting the actual luminance output and using this information to adjust the conversion coefficients. The luminance detecting unit measures the actual luminance, and the conversion coefficient adjusting unit uses this to compensate for leakage, effectively removing the harmful effect while maintaining contrast improvement.
3Use of energy by moving object
If luminance conversion is applied to reduce power consumption, then power consumption is reduced, but color changes are easily perceived in low luminance
Solution Approach 1:
The patent implements feedback by continuously detecting the actual luminance output and using this feedback to adjust the conversion coefficients in real-time. The luminance detecting unit provides feedback to the conversion coefficient adjusting unit, which then modifies the conversion parameters to prevent perceived color changes, creating a closed-loop system that maintains color consistency while reducing power consumption.
Data Source
AI summary
An image processing apparatus has a light source luminance calculating unit which calculates the luminances of the light sources of the plurality of colors of a back light based on an input image, a light source maximum value detecting unit which detects a light source maximum value that is the largest value in the light source luminances of the plurality of colors, a light source luminance correcting unit which corrects the light source luminances to obtain corrected light source luminances so as to reduce the difference among the light source luminances of the plurality of colors if the light source maximum value is smaller than a threshold value, a gradation conversion function calculating unit which calculates a gradation conversion function applied to the input image corresponding to each of the plurality of colors, by using the corrected light source luminance, and a control unit which converts the input image by using the gradation conversion function and outputs the input image to a liquid crystal panel and generates the luminance control signal by using the corrected light source luminance and outputs the luminance control signal to the back light.