Projector Image Correction via Calibration Panel Analysis
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Solution Overview
Problem
Projectors suffer from distortions such as barrel and pincushion distortions due to internal optical lens design and keystone effects caused by non-perpendicular optical axes, leading to inaccurate image projections.
Innovation Solution
An image correction method and system that uses a physical calibration panel and an image capturing apparatus to obtain calibration parameters and homography matrices, performing undistortion and compensation operations to correct both linear keystone and non-linear distortions in projected images, ensuring accurate projection proportions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a projector uses an optical lens set to project images, then the projection function is achieved, but the image suffers from non-linear distortions such as barrel and pincushion distortions
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction parameters for various projection scenarios. Before actual projection, the system determines the appropriate correction parameters based on the projection distance and angle, then applies these corrections to the image data in advance, ensuring distortion-free projection without requiring real-time complex calculations
Solution Approach 2:
The patent utilizes parameter changes by establishing a relationship between projection parameters (distance, angle) and distortion characteristics. The system adjusts correction parameters based on the specific projection conditions, dynamically changing the correction applied to different regions of the image to compensate for optical distortions while maintaining projection functionality
2Adaptability or versatility
If the optical axis is not perpendicular to the projection plane or the optical lens set is installed with skew offset, then the projector can be installed in various positions, but a keystone effect occurs causing linear deformation
Solution Approach 1:
The patent applies preliminary anti-action by pre-calculating the keystone effect based on the detected projection angle and distance. The system generates correction data that counteracts the expected linear deformation before projection occurs, allowing the projector to be installed at various angles while maintaining image accuracy through pre-applied geometric corrections
3Device complexity
If traditional correction methods correct only non-linear or only linear distortion, then the correction process is simple, but the other type of distortion remains uncorrected
Solution Approach 1:
The patent merges the correction of non-linear distortion and linear keystone effect into a unified correction framework. By combining the determination of non-linear correction parameters with linear correction parameters in a single integrated process, the system achieves comprehensive distortion correction without significantly increasing device complexity, as both corrections are applied through coordinated parameter adjustments
Data Source
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AI summary
An image correction method of projector and an image correction system are provided. An image capturing apparatus shoots a physical calibration panel to obtain a first image, and shoots an outputting image of a calibration panel pattern on a projection screen outputted from the projector to obtain a second image. A processor analyzes the first image to obtain a first calibration parameter and a first homography matrix, and performs an undistorting operation for the second image based on the first calibration parameter to obtain a third image. The processor analyzes the third image to obtain a second calibration parameter and a second homography matrix of the projector. The processor performs a compensating operation for an original image to be outputted from the projector based on the second calibration parameter, the second homography matrix and the first homography matrix to obtain a compensated image.