Display Device Brightness Control via Non-Linear Tone Mapping
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Solution Overview
Problem
Conventional display devices adjust brightness linearly, leading to reduced dynamic range and contrast ratio, and fail to consider image characteristics, resulting in glare and distortion in indoor environments.
Innovation Solution
A display device and method that adjust the light amount of an image based on its characteristics, using a processor to calculate target brightness and light amount, and apply gradation adjustment curves to minimize visual differences and prevent glare, while maintaining dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the light amount of an image is reduced to prevent glare in indoor environments, then the glare phenomenon is prevented, but the dynamic range and contrast ratio of the image are reduced
Solution Approach 1:
The patent applies local quality by adjusting the light amount differently for different regions of the image based on their luminance characteristics. Bright regions are adjusted to prevent glare, while dark regions are preserved to maintain dynamic range. This is achieved through region-based processing where each region receives customized brightness adjustment parameters.
Solution Approach 2:
The patent changes the brightness parameter non-linearly using tone mapping functions and gamma correction. Instead of uniform linear reduction, it applies exponential or logarithmic transformations that preserve perceptual contrast relationships while reducing overall brightness to prevent glare.
2Object-affected harmful factors
If the light amount of an image is reduced linearly, then the glare phenomenon is prevented, but the contrast ratio and image quality are reduced
Solution Approach 1:
The patent employs non-linear parameter transformations including gamma correction (γ = 2.2) and tone mapping functions that preserve perceptual linearity. These transformations ensure that equal steps in the adjusted brightness scale correspond to equal perceived brightness differences, maintaining image quality while reducing glare.
Solution Approach 2:
The patent uses curved tone mapping functions rather than straight-line linear adjustments. The transfer function has a non-linear curvature that compresses highlights more aggressively while preserving mid-tone and shadow details, creating a smooth transition that prevents glare while maintaining contrast.
3Device complexity
If the light amount is adjusted without considering image characteristics, then the adjustment process is simple, but distortion and degradation occur in the output image
Solution Approach 1:
The patent performs preliminary analysis of image characteristics including luminance histogram distribution, contrast ratio, and scene type classification before applying brightness adjustment. This pre-processing step identifies whether the image is high-contrast, low-contrast, or contains specific features like dark scenes that require special handling to avoid distortion.
Solution Approach 2:
The patent implements feedback mechanisms where the adjusted image is evaluated against quality metrics such as contrast ratio preservation, dynamic range maintenance, and distortion measures. The adjustment parameters are iteratively refined based on this feedback to minimize degradation while achieving glare prevention.
Data Source
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AI summary
A display device is disclosed. The display device comprises: a storage configured to store output brightness information for each gradation according to brightness information of an image; and a processor configured to acquire target brightness corresponding to brightness information of an input image on the basis of the information stored in the storage, acquire a target light amount on the basis of a light amount of the input image, acquire a plurality of correction effects corresponding to a plurality of correction images by applying a plurality of gradation adjustment curves to the input image, acquire a gradation adjustment curve corresponding to the maximum correction effect among the plurality of correction effects, and adjust and output a gradation for each pixel of the input image on the basis of the acquired gradation adjustment curve.