Digital Optical Imaging System Calibration Using Position Error Vectors
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Solution Overview
Problem
Digital optical imaging systems, particularly those with zoom systems, face challenges in accurately correcting imaging errors such as spherical and chromatic aberrations across various zoom positions, leading to suboptimal image quality due to the complexity and cost of advanced lens systems.
Innovation Solution
A method for calibrating digital optical imaging systems that includes a motorized zoom system, an image sensor, and a logic unit for digital image processing, where an initial calibration process determines position error vectors for each zoom position, forming a distortion model using higher-order polynomials to correct imaging errors across the entire zoom range, enabling precise image correction at all zoom positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex lens systems (planapochromats, apochromats) are used to correct imaging errors, then image quality is improved, but system cost and complexity increase significantly
Solution Approach 1:
The patent replaces complex mechanical optical systems (multiple lens elements) with a digital correction system. A reference image is captured and stored, then during operation, the current image is compared with the reference image and corrected by calculating and applying position error vectors for each pixel. This substitutes physical optical correction with computational correction, achieving high image quality without complex lens assemblies.
Solution Approach 2:
The patent performs preliminary calibration by capturing a reference image at a known good quality setting. This reference image is stored and used as the basis for all subsequent corrections. The position error vectors are pre-calculated and stored, enabling rapid correction during operation without requiring complex real-time optical adjustment mechanisms.
2Adaptability or versatility
If zoom systems are implemented to provide variable magnification, then versatility is improved, but imaging errors (position errors, distortion) increase across different zoom positions
Solution Approach 1:
Instead of using complex mechanical zoom systems with multiple moving lens groups that introduce alignment errors, the patent captures a reference image at each desired zoom position. The correction data is pre-calculated and stored for each zoom level. During operation, the system simply selects the appropriate correction data based on the current zoom position and applies it digitally, eliminating the need for precise mechanical alignment across zoom ranges.
Solution Approach 2:
The patent performs preliminary calibration at each zoom position by capturing reference images and calculating position error vectors before normal operation. These correction data are stored in memory associated with specific zoom positions. When the zoom system is used, the pre-calculated correction data is retrieved and applied, avoiding the need for real-time optical adjustment and maintaining image accuracy across all zoom levels.
3Measurement precision
If manual software correction is used to fix lens distortion, then image quality is improved, but extensive databases and processing time are required
Solution Approach 1:
The patent performs preliminary calibration by capturing reference images and calculating position error vectors for each zoom position before normal operation. The correction data (position error vectors) are pre-calculated and stored in memory. During operation, the system simply retrieves the appropriate correction data based on the current zoom position and applies it to the captured image, enabling rapid correction without extensive real-time processing or large external databases.
Solution Approach 2:
The patent applies local correction by calculating and storing position error vectors for each pixel position in the image. The correction is applied locally to each pixel based on its specific position error relative to the reference image, rather than applying global transformation parameters. This enables precise correction of local distortion artifacts while maintaining efficiency through pre-calculated lookup tables.
Data Source
AI summary
The invention relates to a method for calibrating a digital optical imaging system, comprising at least one motorized or coded zoom system and an image sensor, a method for correcting imaging errors in such an imaging system, and an optical imaging system configured to perform the methods according to the invention. In the calibration method, a reference object is recorded at various zoom positions, and the image is digitally corrected pixel by pixel using a previously determined model. For this purpose, distortion correction coefficients and image position correction coefficients are determined. The actual total magnification of the system is then determined from the corrected image. The model determined in the calibration process also serves to correct imaging errors during operation of the imaging system.