CVBS Edge Detection for Chroma Signal Separation
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Solution Overview
Problem
Conventional image processing systems struggle to accurately detect edges in images due to the limitations of sinusoidal chroma signals, leading to misjudgment of non-chroma components as chroma components, especially at intersections of colors and brightness, and are unable to detect edges with high resolution when the changing period is smaller than the color burst period.
Innovation Solution
The method involves performing different edge detecting procedures on luma and chroma lines, with a higher resolution first edge detecting procedure on non-chroma lines and a second edge detecting procedure on chroma lines, allowing for more precise detection of edges by comparing voltage differences and generating a weighted voltage difference to determine edge existence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-pass filter is used to generate chroma signals from CVBS, then chroma signal extraction is achieved, but non-chroma components are misjudged as chroma components at color and brightness intersections
Solution Approach 1:
The patent performs edge detection before luma/chroma separation to identify edge regions in advance. The edge detecting module scans the CVBS signal and marks edge positions, which are then used to guide the subsequent luma/chroma separating module to avoid misjudging non-chroma components as chroma components at these critical locations.
Solution Approach 2:
The patent introduces an edge detecting module as an intermediary between the CVBS input and the luma/chroma separating module. This intermediary analyzes the signal characteristics and provides edge position information that helps the separating module make accurate decisions about which components are truly chroma signals versus non-chroma components at color intersections.
2Measurement precision
If conventional edge detection is performed on CVBS using sinusoidal chroma signal characteristics, then chroma edges can be detected, but edges with changing periods smaller than color burst period cannot be detected
Solution Approach 1:
The patent employs dynamic edge detection procedures that adapt to different line types. The system determines whether each horizontal line is a chroma line or non-chroma line and applies the appropriate detection procedure accordingly. For non-chroma lines, a first edge detecting procedure is used, while for chroma lines, a second edge detecting procedure is applied, allowing the system to handle edges with varying resolution requirements.
Solution Approach 2:
The patent changes the detection parameters based on the line type. By identifying whether a line contains chroma signals or not, the system adjusts its detection approach - using procedures suitable for non-chroma lines when applicable, and chroma-specific procedures only when necessary. This parameter adaptation enables detection of edges with changing periods smaller than the color burst period.
3Productivity
If luma/chroma separation is performed without prior edge detection, then processing speed is improved, but misjudgment of non-chroma components as chroma components occurs
Solution Approach 1:
The patent performs edge detection as a preliminary action before luma/chroma separation. The edge detecting module scans the CVBS signal and identifies edge positions in advance, creating a map that the luma/chroma separating module can use to avoid misjudgment. This preliminary edge information allows the separation process to proceed more accurately without requiring extensive post-processing corrections.
Data Source
AI summary
An image processing method and an image processing apparatus are provided. After receiving an image signal, the image and apparatus according to the invention first judge whether a target block in the image signal includes a non-chroma line. If the judging result is YES, a first edge detection procedure will be performed on the non-chroma line. If the judging result is NO, a second edge detection procedure will be performed on the target block.