Image Signal Processing Circuit Brightness Emphasis Chroma Protection
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Solution Overview
Problem
Flat panel displays face a challenge in maintaining display quality when the alternating current component of a brightness signal is emphasized, as it can result in a range of the inversely-converted image signal exceeding the displayable range, leading to reduced chroma and deteriorated display quality.
Innovation Solution
An image signal processing circuit that includes a color converter, a brightness emphasizer, a brightness limiter, and a color inverse converter, which converts image signals to a brightness signal and color difference signals, emphasizes the alternating current component of the brightness signal, and limits the brightness signal within specific upper and lower limits based on the color difference signals to prevent chroma deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the alternating current component of the brightness signal is emphasized to improve display quality, then the display quality is improved, but the range of the inversely-converted image signal exceeds the displayable range causing chroma deterioration
Solution Approach 1:
The image signal processing is segmented into separate color difference signal processing and brightness signal processing paths. The brightness signal is processed to emphasize its alternating current component, while the color difference signals remain unchanged. This segmentation allows independent optimization of brightness enhancement without adversely affecting color accuracy, resolving the contradiction between display quality improvement and displayable range maintenance.
Solution Approach 2:
The brightness signal acts as an intermediary that is separately processed and then combined with the color difference signals during inverse conversion. By processing the brightness signal independently through emphasis filtering and then recombining it with the original color difference signals, the system achieves display quality improvement while maintaining the integrity of the color information within the displayable range.
2Manufacturing precision
If the brightness signal is enhanced by emphasizing its alternating current component, then the display quality is improved, but the chroma of the inversely-converted image signal becomes lower
Solution Approach 1:
The signal processing is divided into independent color difference and brightness components. The brightness component is enhanced through alternating current emphasis while the color difference components are preserved without modification. This segmentation ensures that chroma information is not lost during the brightness enhancement process, as the color difference signals remain intact and are used directly in the inverse conversion.
Solution Approach 2:
Different processing operations are applied to different components of the image signal. The brightness signal receives alternating current emphasis to improve display quality, while the color difference signals receive no processing to preserve chroma information. This localized quality approach ensures that each component is optimized for its specific function without compromising the other.
Data Source
AI summary
An image signal processing circuit of a display apparatus includes: a color converter converting first image signals to a first brightness signal, a first color difference signal, and a second color difference signal; a brightness emphasizer outputting a second brightness signal obtained by emphasizing an alternating current component of the first brightness signal; a brightness limiter determining an upper limit value and a lower limit value based on the first color difference signal and the second color difference signal and converting the second brightness signal to a third brightness signal between the upper limit value and the lower limit value; and a color inverse converter converting the third brightness signal, the first color difference signal, and the second color difference signal to second image signals.