Tone Adjustment Unit for Luminance Balance Under Ambient Light
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Solution Overview
Problem
Existing image adjustment technologies struggle to maintain the balance of luminance in images when viewed in different environments, particularly under varying ambient light conditions, leading to decreased contrast and visibility issues.
Innovation Solution
An image adjustment device and method that adjusts luminance values using a tone curve with a non-zero inclination, taking into account the effects of ambient light, to ensure the balance of luminance is maintained and contrast is enhanced, even under conditions of decreased contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If partial mapping is performed to adjust luminance in specific regions, then local luminance control is improved, but the overall luminance balance of the image is destroyed
Solution Approach 1:
The patent divides the image into multiple regions based on luminance characteristics and processes each region with appropriate tone mapping parameters. This allows local luminance control in specific regions while maintaining the overall luminance balance through coordinated processing of all regions.
Solution Approach 2:
The patent applies different tone mapping parameters to different regions of the image based on their specific luminance characteristics. By tailoring the processing to local requirements rather than applying uniform processing, it achieves local luminance control while preserving the global luminance balance.
2Device complexity
If tone mapping is performed without considering ambient light, then processing simplicity is improved, but the image visibility in actual viewing environments is worsened
Solution Approach 1:
The patent performs preliminary measurement of ambient light conditions before executing tone mapping processing. By obtaining ambient light information in advance and incorporating it into the tone mapping parameters, the system ensures optimal image visibility in the actual viewing environment without significantly increasing processing complexity.
Solution Approach 2:
The patent uses ambient light sensor data as feedback to dynamically adjust tone mapping parameters. This feedback mechanism allows the system to adapt to changing viewing conditions and maintain reliable image visibility while keeping the processing framework relatively simple.
3Device complexity
If the tone curve inclination is zero in certain regions, then processing simplicity is improved, but the discrimination threshold increases causing black-out and white-out
Solution Approach 1:
The patent implements dynamic tone curve adjustment where the inclination is adapted based on local luminance characteristics and ambient light conditions. Rather than using a fixed zero inclination, the system dynamically determines appropriate inclination values to maintain luminance discrimination while managing processing complexity.
Solution Approach 2:
The patent changes the tone curve parameters including inclination based on local image characteristics and viewing conditions. By adjusting these parameters dynamically rather than using fixed values, the system maintains luminance discrimination capability while keeping the processing approach flexible and manageable.
Data Source
AI summary
A tone adjustment unit assumes that the following relationship is satisfied: LO=DO+Da=TD(I)+Da=TL(I), in which I represents a luminance value normalized to have a maximum value of one in first image data, DO represents a luminance value normalized to have a maximum value of one in second image data, Da represents a luminance value under ambient light during viewing, LO represents a luminance value of the second image data while taking into consideration effects of the ambient light during viewing, TD(I) represents a tone curve used for conversion, and TL(I) represents a tone curve taking into consideration the environment. The tone curve TD(I) is adjusted so that a function representing an inclination γ(I) after converting LO=TL(I) to a double logarithmic plot is non-zero over an entire dynamic range.