Image Display Third Tone Mapping for Mid-High Gray Detail
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Solution Overview
Problem
Existing image display apparatuses struggle to effectively enhance grayscale expression, particularly in mid and high gray levels, despite advancements in larger panels and higher resolutions.
Innovation Solution
The image display apparatus employs a signal processing device that performs third tone mapping by combining first and second tone mappings based on input and reference peak luminances, adjusting the ratio and amount of luminance change to enhance grayscale expression, especially in mid and high gray levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional tone mapping is used for HDR images, then peak luminance contrast is improved, but grayscale expression in mid and high gray levels deteriorates
Solution Approach 1:
The patent divides the tone mapping process into multiple segments: first tone mapping for peak luminance control and second tone mapping for grayscale expression. By segmenting the processing into different stages with different priorities, the system can optimize peak luminance contrast in the first stage while preserving grayscale expression in the second stage, resolving the contradiction between these two competing requirements.
Solution Approach 2:
The patent dynamically adjusts processing parameters based on image characteristics. When the input image has high peak luminance, the system applies aggressive peak luminance compression while maintaining grayscale fidelity. When peak luminance is moderate, it prioritizes grayscale expression. This parameter adaptation allows the system to resolve the contradiction by adjusting the balance between peak luminance contrast and grayscale precision based on actual image content.
2Adaptability or versatility
If aggressive peak luminance compression is applied, then dynamic range is improved, but mid and high gray level details are lost
Solution Approach 1:
The patent performs preliminary peak luminance compression through first tone mapping before the second tone mapping stage. By pre-compressing the peak luminance values, the system creates headroom that prevents clipping while preserving the dynamic range. This preliminary action ensures that subsequent grayscale processing can operate on compressed luminance values without losing mid and high gray level details, thus resolving the information loss problem.
Solution Approach 2:
The patent introduces an intermediate processing stage between peak luminance compression and final grayscale rendering. The first tone mapping acts as an intermediary that compresses peak luminance while the second tone mapping serves as another intermediary that restores grayscale expression. These intermediary stages mediate between the conflicting requirements of dynamic range expansion and detail preservation, allowing both goals to be achieved.
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AI summary
An image display apparatus is disclosed. The image display apparatus according to an embodiment of the present disclosure includes: a display; and a signal processing device to output an image signal to the display, wherein, in response to an input peak luminance of an input image being equal to or lower than a reference peak luminance, the signal processing device is configured to perform third tone mapping, based on a combination of first tone mapping corresponding to the input peak luminance and second tone mapping corresponding to the reference peak luminance, and output a signal corresponding to the third tone mapping. Accordingly, grayscale expression can be enhanced.