Signal Processing Knee Correction for Dynamic Range Preservation
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Solution Overview
Problem
Existing knee correction methods in image processing can unintentionally lower the dynamic range of the input signal and cause signal clipping and color curving on high-luminance sides if the knee point and slope settings are inappropriate.
Innovation Solution
A signal processing device that includes a knee correction processing unit to adjust high-luminance side gradation correction parameters, calculating the correction amount to maintain the dynamic range based on the maximum output level, and generating and applying a correction curve to the tone curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If knee correction is applied to correct high-luminance side gradation, then image quality is improved, but dynamic range of the input signal is unintentionally lowered
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the knee slope and knee point positions based on the input signal's dynamic range and maximum output level. The correction amount calculating unit computes appropriate correction parameters that maintain the dynamic range while achieving the desired high-luminance side gradation correction, preventing unintended compression of the dynamic range.
Solution Approach 2:
The patent implements feedback mechanisms where the correction amount calculating unit references the maximum output level and dynamic range information to adjust the knee correction parameters. This feedback loop ensures that the correction curve generation unit creates appropriate correction curves that preserve the input signal's dynamic range characteristics while correcting high-luminance gradation.
2Manufacturing precision
If knee point and knee slope settings are adjusted to correct high-luminance side gradation, then image processing is improved, but signal clipping occurs on the display device side
Solution Approach 1:
The patent uses feedback from the maximum output level information to adjust the knee correction parameters. The correction amount calculating unit references the maximum output level to determine appropriate correction amounts that prevent the corrected signal from exceeding the display device's capabilities, thereby avoiding signal clipping while maintaining image processing quality.
Solution Approach 2:
The patent dynamically changes the knee point position and knee slope parameters based on the maximum output level and input signal characteristics. This adaptive parameter adjustment ensures that the correction curve does not push the output signal beyond the display device's range, preventing clipping while achieving the desired high-luminance correction.
3Device complexity
If knee correction parameters are not appropriately set, then image processing is simplified, but color curving occurs on the high-luminance side
Solution Approach 1:
The patent applies parameter changes by automatically adjusting knee point and knee slope values based on the input signal's dynamic range and maximum output level. This automated parameter adaptation maintains color accuracy on the high-luminance side without requiring complex manual tuning, as the system dynamically selects appropriate correction parameters that prevent color curving while keeping the processing algorithm relatively simple.
Data Source
AI summary
A signal processing device has a storage unit configured to hold data for a tone curve to be applied to an input image; a correction parameter acquisition unit configured to acquire a high-luminance side gradation correction parameter for adjusting a correction amount of a high-luminance side gradation correction for the tone curve; a correction amount calculating unit configured to calculate the correction amount for the high-luminance side gradation correction such that a dynamic range of the tone curve is maintained based on a maximum output level for the tone curve and the high-luminance side gradation correction parameter; a correction curve generating unit configured to generate a correction curve by applying the high-luminance side gradation correction to the tone curve; and a correction curve application unit configured to apply the correction curve to the input image.