Video Signal Processing Device Luminance Saturation Segmentation
Solution Overview
Problem
Existing video-signal-processing devices fail to maintain constant hue and high saturation levels in bright areas, leading to undesirable color changes and loss of saturation when imaging subjects against backlight, particularly in bright conditions.
Innovation Solution
A video-signal-processing device with a luminance conversion section performing level compression at a consistent luminance adjustment compression ratio, combined with a saturation conversion section that adjusts saturation levels using a saturation compression ratio based on the minimum or maximum levels of compressed primary-color signals, ensuring hue constancy and maintaining saturation even in bright conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Knee correction is performed on each primary-color signal independently, then highlight areas are compressed into dynamic range, but hue changes occur in bright areas
Solution Approach 1:
The signal processing is segmented into two independent pathways: luminance processing (Y signal) and saturation processing (C signal). The luminance conversion section processes the Y signal to compress highlight areas, while the saturation conversion section processes the C signal separately. This segmentation allows each pathway to be optimized independently, preventing hue changes while achieving dynamic range compression.
Solution Approach 2:
The patent introduces an intermediary approach by converting the primary-color signals (R, G, B) into luminance-saturation-color (Y-C) space as an intermediate representation. This intermediate space allows the luminance and saturation components to be processed separately through their respective conversion sections, avoiding the hue changes that occur when processing primary-color signals independently.
2Reliability
If clip processing is applied to restrict color signals to white clip level, then broadcast standards are met, but saturation is lost in bright areas
Solution Approach 1:
The processing is segmented so that luminance clipping and saturation adjustment occur in separate sections. The luminance conversion section handles the clipping to meet broadcast standards, while the saturation conversion section independently adjusts saturation levels using a saturation compression ratio, preventing saturation loss that would occur with traditional clip processing.
Solution Approach 2:
The patent changes the processing parameter from fixed-level clipping to dynamic saturation compression ratio adjustment. Instead of abruptly clipping signals at the white clip level, the saturation conversion section dynamically adjusts the saturation compression ratio based on the luminance level, maintaining saturation in bright areas while still complying with broadcast standards.
3Illumination intensity
If level compression is performed on primary-color signals to compress highlight areas, then dynamic range is reduced, but hue and saturation change
Solution Approach 1:
The patent uses the luminance-saturation-color (Y-C) color space as an intermediary representation. By converting primary-color signals to this intermediate space, the luminance component (Y) can be compressed independently without affecting the saturation component (C). This allows highlight compression while maintaining color consistency, as the saturation is preserved in the intermediate representation and then converted back to primary-color signals.
Solution Approach 2:
The color signal processing is segmented into luminance processing and saturation processing pathways. The luminance conversion section performs level compression on the Y signal to compress highlight areas, while the saturation conversion section maintains the C signal integrity. This segmentation ensures that highlight compression does not cause hue or saturation changes.
Data Source
AI summary
A video-signal-processing device has luminance conversion section that performs level compression on three input primary-color signals of a color video signal at a same luminance adjustment compression ratio with a hue and a saturation of the color video signal being kept constant, thereby generating three compressed primary-color signals. The device also has saturation conversion section that performs level conversion on the three compressed primary-color signals by using a saturation compression ratio if a maximum level of at least one of the three compressed primary-color signals exceeds a first level. The saturation conversion section sets the saturation compression ratio by using a minimum level one of the three compressed primary-color signals.