Ambient-Light Image Enhancement for Low-Gray Display Visibility
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Solution Overview
Problem
Automotive display technologies struggle to maintain visibility of lower gray shades under varying ambient lighting conditions, compromising the visibility of important image content while increasing power consumption.
Innovation Solution
An image enhancement system utilizing an ambient light sensor, circuit, and processor to generate a histogram and a gray shade look-up table, adjusting the display luminance to enhance visibility of lower gray shades by applying a combination of start point, intermediate stretching, and end point functions, while maintaining constant contrast ratios and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If automatic luminance control methods are used to maintain visibility of peak-white gray shades, then visibility of peak-white gray shades is improved, but visibility of lower gray shades is compromised
Solution Approach 1:
The patent applies different processing strategies to different gray shade ranges. Lower gray shades are enhanced using a lookup table that maps input gray shades to output gray shades, while peak-white gray shades maintain their original luminance characteristics. This local differentiation allows lower gray shades to become visible without compromising the visibility of peak-white gray shades.
Solution Approach 2:
The patent changes the luminance parameters of lower gray shades by applying a lookup table that transforms input gray shade values to enhanced output gray shade values. This parameter transformation allows lower gray shades to achieve sufficient luminance for visibility while maintaining the overall luminance control strategy for peak-white shades.
2Illumination intensity
If display luminance is increased to maintain visibility under varying ambient lighting, then visibility is improved, but power consumption increases
Solution Approach 1:
Instead of increasing the luminance of the entire display, the patent applies luminance enhancement only to lower gray shades that fall below the visibility threshold. This localized approach ensures that power is consumed only where necessary to maintain visibility, rather than increasing overall display luminance.
Solution Approach 2:
The patent applies partial action by selectively enhancing only the lower gray shades that require visibility improvement. The lookup table transforms only those gray shades that are below the visible threshold, leaving higher gray shades unchanged, thereby minimizing the energy required for enhancement.
3Loss of information
If lower gray shades are enhanced to improve visibility, then visibility of lower gray shades is improved, but contrast ratio may be affected
Solution Approach 1:
The system continuously monitors the ambient lighting conditions and dynamically adjusts the lookup table to maintain appropriate contrast ratios. By measuring the luminance of lower gray shades and comparing it against visibility thresholds, the system provides feedback that drives real-time adjustments to the enhancement parameters, ensuring contrast ratio is preserved while maintaining visibility.
Solution Approach 2:
The patent implements a dynamic lookup table that adapts to changing ambient lighting conditions. The system continuously updates the gray shade mapping based on current luminance measurements, allowing the contrast ratio to be maintained dynamically rather than being fixed. This dynamic adjustment ensures that lower gray shades remain visible without compromising overall contrast.
Data Source
AI summary
An image enhancement system includes an ambient light sensor, a circuit and a processor. The ambient light sensor is operational to measure an ambient light level. The circuit is operational to: generate a histogram based on an input video signal; export the histogram; receive a gray shade look up table; and generate an output video signal by converting a plurality of gray shades in the input video signal based on the gray shade look up table. The processor is operational to: receive the histogram from the circuit; develop the gray shade look up table based on the histogram and the ambient light level; and transfer the gray shade look up table to the circuit.