Sub-pixel Light Spot Center Positioning via CCD Displacement
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Solution Overview
Problem
Existing spot center positioning methods are limited in handling specific spot scenes, particularly failing to achieve high precision for light spots with blurry edges, asymmetrical distribution, and saturated conditions.
Innovation Solution
A method utilizing a high-precision displacement platform to move and cut a CCD image plane in the x and y directions, recording gray value changes, establishing a mapping relationship, performing differential and interpolation fitting to determine sub-pixel center coordinates, suitable for various light spot scenes including those with strong and weak distributions and blurred edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of the CCD is increased to improve positioning accuracy, then measurement precision is improved, but device cost increases significantly
Solution Approach 1:
The patent segments the spot image into multiple small sub-images by moving the CCD and capturing images at different positions. Each sub-image contains partial information about the spot, and by combining these segmented measurements, the system achieves high positioning precision without requiring a high-resolution CCD
Solution Approach 2:
The patent introduces a displacement platform as an intermediary device to move the CCD relative to the spot. This intermediary mechanism enables the system to gather multiple measurements from different positions, effectively achieving high positioning accuracy through software processing rather than hardware upgrades
2Ease of operation
If the centroid method is used for positioning, then the algorithm is simple and clear, but it can only achieve ideal results for targets with symmetrical grayscale distribution
Solution Approach 1:
The patent transforms the static centroid calculation into a dynamic measurement process by moving the CCD and capturing multiple images at different positions. This dynamic approach allows the system to adapt to various spot distributions (symmetrical, asymmetrical, blurred, saturated) while maintaining algorithmic simplicity through consistent differential calculation procedures
3Productivity
If the ellipse fitting method is used, then the method is relatively simple and efficient, but the choice of threshold has implications on the final positioning result, especially for spots with blurry edges
Solution Approach 1:
The patent performs preliminary actions by capturing multiple images at different CCD positions before final processing. This preliminary multi-position data collection eliminates the need for threshold selection during processing, as the differential calculation method directly uses gray value changes without requiring binary thresholding, thereby improving both efficiency and precision for blurred spots
4Measurement precision
If the Gaussian fitting method is used, then the method can better obtain the spot center with strong and weak distribution while suppressing the influence of noise, but it cannot obtain position information for a saturated spot
Solution Approach 1:
The patent creates a universal positioning method that works across multiple spot conditions (strong distribution, weak distribution, blurred edges, and saturated spots). The differential calculation approach based on gray value changes during CCD movement provides a unified solution that adapts to different spot characteristics without requiring separate algorithms for different scenarios
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves sub-pixel level accuracy with an error less than 1% of pixels, effectively positioning spot centers across multiple scenes, including those with asymmetrical distribution and saturated spots, while maintaining high measurement precision.
Implementation Method 1
The spot center positioning method drives the CCD image plane to move in the x direction and y direction through a displacement platform, selects the target pixel to move and cut the spot, and records the gray value of the target pixel changes
Data Source
AI summary
A spot sub-pixel center positioning method based on pixel movement and cutting, the method includes driving the CCD image plane to move along the x direction and the y direction through a displacement platform, selecting target pixels to move and cut the spot, and recording the gray value change of the target pixels, constructing the mapping relationship between gray value and displacement, performing differential transformation on the gray value and displacement curve, and finally performing interpolation fitting to obtain the sub-pixel coordinate value of the center point of the light spot. The measurement accuracy can be maintained within ½ of the single-step displacement of cutting. The method is not only suitable for strong and weak distribution of light spots, but also for fully saturated light spots, and also for asymmetrically distributed and blurred edges. It also has a good measurement effect and can handle a variety of spot scenes.