Image Processing Device Blurring Correction for 3D Shape Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The focus variation method for three-dimensional shape measurement struggles with accurately measuring objects containing both high and low reflectivity regions, as the strong contrast of blurring in high reflectivity areas overwhelms the contrast of low reflectivity surfaces, leading to improper measurement of low reflectivity portions.
Innovation Solution
An image processing device that corrects blurring in images by applying a frequency-domain restoration filter based on the point spread function of the optical system, using techniques such as inverse Fourier transforms and Wiener filters to enhance the focusing degree evaluation values for each pixel, thereby generating accurate three-dimensional shape data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a polarizing filter is used to reduce direct reflection and acquire scattered light, then measurement accuracy of low reflectivity regions is improved, but light amount decreases and exposure time is prolonged
Solution Approach 1:
The patent replaces the mechanical/optical solution (polarizing filter) with a computational image processing solution. By applying deconvolution processing using the point spread function to images captured without a polarizing filter, the system achieves measurement accuracy comparable to using a polarizing filter while avoiding the light loss and prolonged exposure time issues.
2Measurement precision
If a polarizing filter is used to reduce direct reflection, then measurement accuracy of low reflectivity regions is improved, but the number of components increases
Solution Approach 1:
The patent eliminates the need for a polarizing filter by substituting it with computational processing. The image processing unit applies deconvolution using the point spread function to process images captured by the imaging device alone, thereby achieving the same measurement accuracy improvement without adding any optical components.
3Measurement precision
If blurring correction based on point spread function is applied, then measurement accuracy of low reflectivity regions is improved, but processing complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing the point spread function for each focal position before actual measurement. During measurement, the image processing unit simply retrieves the appropriate point spread function and applies deconvolution processing, which simplifies the real-time processing complexity while maintaining high measurement accuracy.
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 approach allows for the accurate acquisition of three-dimensional shape data by reducing the influence of blurring in high reflectivity areas, enabling precise measurement of low reflectivity regions and improving overall measurement accuracy.
Implementation Method 1
applies, to the images in a frequency domain obtained by Fourier transform of the images, a frequency-domain restoration filter based on the point spread function
Implementation Method 2
a plurality of images of an object to be measured which are different in focal position are taken
Data Source
AI summary
An image processing device acquires a plurality of images of an object to be measured by an imaging device, the plurality of images being taken while varying a focal position, and corrects blurring in the acquired plurality of images based on a point spread function for each focal position of an image forming optical system in the imaging device. The image processing device also calculates, for the plurality of images after correction of the blurring, an evaluation value for a focusing degree for each pixel, and generates three-dimensional shape data of the object to be measured based on the calculated evaluation value for the focusing degree for each pixel.