Image Visibility in High Illuminance via LUT Lightness Chroma Adjustment
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Solution Overview
Problem
Images displayed on personal portable terminals, such as digital cameras and camera phones, become less visible in high-illuminance environments due to reduced visibility caused by external light, leading to a diminished user experience.
Innovation Solution
An apparatus and method that utilize a lookup table (LUT) to increase the lightness and chroma of images and enhance local contrast, employing an illuminance sensing module, LUT generating module, image mapping module, and local contrast increasing module to adjust image data according to external illuminance, ensuring improved visibility in high-illuminance conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If image data is displayed directly on the display screen, then the display structure remains simple, but the visibility of the image is drastically reduced in high illuminance environments
Solution Approach 1:
The system performs preliminary image processing by generating a LUT with adjusted lightness and chroma values before display. The LUT generating module pre-calculates compensation values based on measured external illuminance, and the image mapping module pre-maps the input image data using these values, so that the image is already optimized for high illuminance conditions before reaching the display screen.
Solution Approach 2:
The system changes the parameters of the image data by adjusting lightness and chroma through the LUT. The LUT generating module modifies the lightness parameter to increase brightness and the chroma parameter to enhance color saturation, transforming the image data to compensate for the harsh lighting conditions and maintain visibility.
2Object-affected harmful factors
If image processing operations are added to improve visibility, then image visibility in high illuminance environments is improved, but the device complexity increases
Solution Approach 1:
The system introduces a LUT as an intermediary data structure between the input image and the display output. The LUT acts as a pre-computed lookup table that stores adjusted color values, serving as a mediator that translates input image data into display-optimized data without requiring complex real-time processing during display operations.
Solution Approach 2:
The complex processing operations are performed in advance to generate the LUT, rather than during actual display operations. The LUT generating module pre-calculates all necessary color adjustments based on external illuminance measurements, storing these adjustments in a lookup table that can be quickly applied during display without adding significant processing complexity to the display path.
3Object-affected harmful factors
If lightness and chroma are increased to maintain visibility, then image visibility in bright environments is improved, but local contrast may be distorted
Solution Approach 1:
The system applies different processing treatments to different regions of the image by performing local contrast enhancement after the LUT mapping. The local contrast increasing module analyzes local regions and applies contrast adjustments specifically where needed, preserving the natural contrast relationships in different parts of the image while maintaining overall visibility in high illuminance conditions.
Solution Approach 2:
The system performs preliminary lightness and chroma adjustments through the LUT before applying local contrast enhancement. This sequential approach allows the LUT to establish the base brightness and color levels for visibility, while the subsequent local contrast module fine-tunes regional contrast without affecting the overall lightness and chroma adjustments already made.
Data Source
AI summary
An apparatus and method for improving visibility of an image. The apparatus includes: a lookup table (LUT) generating module generating an LUT having image data in a high illuminance environment corresponding to image data of an input image set therein so as to increase lightness and chroma of the input image according to external illuminance; an image mapping module mapping the image data of the input image into the image data in the high illuminance environment on the basis of the generated LUT; and a local contrast increasing module increasing local contrast of the mapped image data using a parameter for adjusting the local contrast according to the external illuminance.