Video Signal Processor Y/C Separation Circuit
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Solution Overview
Problem
Conventional video signal processors face challenges in accurately detecting image motion in composite video signals and removing dot interference and cross-color interference components, especially when processing component video signals, which can result in decreased image quality and increased circuit complexity and cost.
Innovation Solution
A video signal processor that includes a simplified Y/C separation circuit, a color demodulation circuit, and a three-dimensional processing portion to selectively process composite and component video signals, using frame memories and motion detection circuits to remove image quality debasing components without requiring extensive three-dimensional processing for all inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If three-dimensional processing is applied to all video signals, then image quality is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies three-dimensional processing selectively based on signal type: component video signals undergo three-dimensional processing to remove dot interference and cross-color interference, while composite video signals use simplified Y/C separation. This localized approach ensures high image quality where needed while avoiding unnecessary complexity for signals that don't require extensive processing.
Solution Approach 2:
The patent segments the video signal processing into two distinct paths: one for component video signals (Y, Pb, Pr) that includes three-dimensional processing, and another for composite video signals (Y, C) that uses simplified separation. This segmentation allows the system to apply appropriate processing complexity to each signal type independently, optimizing both image quality and device complexity.
2Manufacturing precision
If three-dimensional processing is applied to component video signals, then interference components are removed, but processing time and complexity increase
Solution Approach 1:
The patent performs preliminary Y/C separation using a simplified method before applying three-dimensional processing to component signals. By pre-separating the luminance and color components, the system prepares the signals in advance for the more intensive three-dimensional processing, reducing the actual processing time required to remove dot interference and cross-color interference.
Solution Approach 2:
The patent applies three-dimensional processing specifically to the color difference signals (Pb, Pr) while using simplified processing for luminance signals where interference is less critical. This partial application of processing removes the most problematic interference components without subjecting all signal components to maximum processing, thereby reducing overall processing time while maintaining signal purity.
3Measurement precision
If motion detection uses frames with different color signal phases, then motion detection accuracy decreases, but processing speed increases
Solution Approach 1:
The patent utilizes the periodic nature of color signal phase rotation in NTSC and PAL systems. By detecting motion using frames with the same color phase (e.g., every other frame in NTSC where phase rotates 180° per frame), the system maintains high motion detection accuracy while processing at regular intervals, balancing accuracy requirements with processing speed constraints.
Data Source
AI summary
A simplified Y/C separation circuit separates a composite video signal into a first luminance signal and a first color signal without subjecting the composite video signal to three-dimensional processing. A color demodulation circuit color-demodulates the first color signal into a first color difference signal. A three-dimensional processing portion removes an image quality debasing component by performing three-dimensional processing with respect to the first luminance signal and the first color difference signal or a second luminance signal constituting a component video signal and a second color difference signal. A selector selectively supplies the first luminance signal and the first color difference signal or the second luminance signal and the second color difference signal to the three-dimensional processing portion.