Lensless Camera Calibration Using Simulation Images
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Solution Overview
Problem
Lensless cameras face challenges in calibrating positional and geometrical variations between masks and sensors, leading to suboptimal image restoration due to the need for extensive pattern presentation and increased costs, especially when using non-visible light wavelengths.
Innovation Solution
An image processing apparatus that calibrates lensless cameras by using a signal processing unit to generate restored images based on unique positional relation data between the mask and sensor, utilizing a photographed point light source and simulation images to apply corrections, reducing the need for extensive pattern presentation and minimizing costs across various wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration using multiple linear patterns is used, then measurement precision of positional relation is improved, but productivity and processing time deteriorate due to enormous number of patterns required
Solution Approach 1:
The patent uses a simulation image that copies the characteristics of multiple linear patterns into a single composite image. This simulation image contains encoded positional and geometrical relation information that can be extracted through image processing, replacing the need to physically present numerous linear patterns during calibration.
Solution Approach 2:
The calibration data (positional and geometrical relations) is calculated and stored in advance in the simulation image before the actual calibration process. When calibration is needed, this pre-prepared simulation image is simply read and processed, eliminating the time-consuming process of presenting multiple patterns during calibration.
2Measurement precision
If conventional calibration using multiple linear patterns is used, then measurement precision of positional relation is improved, but loss of time increases due to enormous calibration process
Solution Approach 1:
The simulation image encodes all necessary calibration information in a single image file, copying the equivalent information that would otherwise require numerous linear patterns. This allows calibration data to be extracted quickly through automated image processing rather than through lengthy sequential pattern presentation.
Solution Approach 2:
The patent replaces the mechanical process of physically presenting multiple linear patterns with an information-based approach using a simulation image. The calibration information is embedded in the image data and extracted through computational methods, substituting physical pattern presentation with digital information processing.
3Measurement precision
If display apparatus for presenting multiple linear patterns is used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
Instead of requiring a complex display apparatus to present multiple linear patterns, the patent copies all necessary calibration information into a single simulation image. This simple image file replaces the need for complex pattern generation and switching hardware.
Solution Approach 2:
The simulation image serves multiple functions simultaneously: it contains positional relation data, geometrical relation data, and calibration information all in one universal format. This single image can be used for various calibration purposes without requiring different physical pattern sets or specialized display equipment.
Data Source
AI summary
A configuration is realized that can execute image processing reflecting data unique to camera, such as positional relation information between a mask and an image sensor of a lensless camera, to generate a highly accurate restored image. A signal processing unit that receives a photographed image as an output of the image sensor of the lensless camera to generate a restored image is included, and the signal processing unit executes image processing using data unique to camera generated based on at least the positional relation information of the mask and the image sensor of the lensless camera to generate the restored image. The data unique to camera is data generated in a comparison process of a photographed image, which is obtained by photographing one point light source in a forward direction of an optical axis of the lensless camera, and a reference image. The reference image is a simulation image estimated to be acquired in a case where a positional relation between the mask and the image sensor indicates reference positions.