Display Luminance Control via Ambient Sensing and WAPL Correction
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Solution Overview
Problem
Existing display devices, particularly outdoor LCDs, fail to provide optimal luminance and visibility due to inadequate consideration of viewing environments, distances, and image characteristics, leading to issues like glare, low luminance, and image distortion.
Innovation Solution
A method and device that determine final luminance by combining sensed ambient illumination, temperature, and viewing distance, and apply a weighted average picture level (WAPL) to adjust the display's luminance, using a luminance controller to set maximum luminance based on these factors and correct it for temperature and viewing distance, while an image processor applies differential gains to improve image characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If luminance is increased to improve visibility in high ambient illumination, then visibility is improved, but glare occurs when viewing distance is very short
Solution Approach 1:
The system dynamically adjusts luminance based on real-time sensing of ambient illumination and viewing distance. The luminance controller modifies display output according to changing environmental conditions and user position, transitioning from static to adaptive luminance control to prevent glare while maintaining visibility.
Solution Approach 2:
The system uses sensors to detect ambient illumination levels and viewing distance, feeding this information back to the luminance controller which then adjusts display luminance accordingly. This closed-loop feedback mechanism enables the system to automatically optimize visibility while preventing glare based on actual viewing conditions.
2Object-affected harmful factors
If luminance is decreased to reduce glare, then glare is reduced, but visibility decreases in high ambient illumination
Solution Approach 1:
The system employs dynamic luminance adjustment that responds to both ambient illumination levels and viewing distance. By continuously adapting luminance output based on sensed conditions, the system maintains optimal visibility across varying environments while preventing glare when users are close to the display.
Solution Approach 2:
The system changes multiple parameters simultaneously - luminance output, gamma correction curves, and differential gains - based on sensed environmental conditions. This multi-parameter adjustment allows the system to optimize both visibility and glare reduction by modifying image characteristics in addition to overall luminance levels.
3Device complexity
If luminance control is applied without considering image characteristics, then luminance adjustment is simple, but gray-level banding occurs in output image
Solution Approach 1:
The system modifies multiple image parameters including luminance levels, gamma correction curves, and differential gains based on ambient conditions. By adjusting these parameters in combination, the system maintains image quality and prevents gray-level banding while adapting to different viewing environments.
Solution Approach 2:
The image processor acts as an intermediary between the luminance controller and the display panel. It applies complex image processing operations including WAPL calculation and differential gain adjustment to prevent banding, while the luminance controller handles overall luminance management, dividing the complexity across multiple processing stages.
4Device complexity
If gamma correction is applied without considering surrounding environment and viewing distance, then processing is simple, but visibility decreases and picture quality deteriorates
Solution Approach 1:
The system dynamically adjusts gamma correction curves based on sensed ambient illumination and viewing distance. Instead of using a fixed gamma curve, the system adapts gamma parameters to match viewing conditions, improving visibility and picture quality in varying environments.
Solution Approach 2:
The system changes gamma correction parameters along with luminance levels based on environmental sensing. By coordinating adjustments to both luminance and gamma curves, the system maintains optimal picture quality and visibility across different viewing conditions.
Data Source
AI summary
The present invention relates to a display device which can provide optimal luminance and visibility to viewers by considering a viewing environment, a viewing distance and image characteristics in an associated manner and a method for driving the same. The method for driving a display device includes: determining final luminance by applying sensed results of ambient illumination, ambient temperature and a viewing distance from a user in an associated manner; adjusting luminance of the display device according to the determined final luminance; and calculating a weighted average picture level (WAPL) from an input image, calculating a differential gain per gray level according to the calculated WAPL, correcting the input image by applying the calculated differential gain per gray level to the input image and outputting the corrected input image.