Digital Camera Distortion Correction via Coordinate Transform
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Solution Overview
Problem
Wide-angle lenses with high distortion aberration cause noticeable optical distortion in digital images, leading to unnatural images with curved straight lines, while minimizing distortion aberration results in prominent wide-angle distortion, especially affecting group images and building captures.
Innovation Solution
An imaging apparatus with a taking lens, image sensor, and distortion corrector that applies image conversion processing to correct optical and wide-angle distortion, using a correction selector to choose between distortion correction modes based on the type of subject and presence of human faces, employing coordinate transform processing with correction coefficient tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a lens with large distortion aberration is used to minimize wide-angle distortion, then wide-angle distortion is reduced, but optical distortion is promoted excessively causing unnatural images with curved straight lines
Solution Approach 1:
The patent applies image conversion processing that changes the parameter space of the image data by applying a coordinate transformation based on distortion correction tables. This transforms the distorted image coordinates to corrected coordinates, simultaneously addressing both wide-angle distortion and optical distortion through parameter transformation rather than physical lens modification
Solution Approach 2:
The patent replaces the mechanical/lens-based distortion correction approach with an image processing-based correction. Instead of using a lens with large distortion aberration to minimize wide-angle distortion, the system uses digital image conversion processing to correct both types of distortion, substituting physical optical means with electronic processing means
2Object-generated harmful factors
If a lens with small distortion aberration is used, then optical distortion is minimized, but wide-angle distortion becomes prominent especially in group images and building captures
Solution Approach 1:
The patent uses image conversion processing with coordinate transformation to change the parameter space of the image data. By applying the transformation based on distortion correction tables, the system corrects wide-angle distortion while maintaining optical distortion correction, achieving both goals simultaneously through parameter transformation
Solution Approach 2:
The patent creates a universal distortion correction system that can handle both optical distortion and wide-angle distortion using the same image conversion processing mechanism. The distortion correction tables and processing algorithm serve multiple functions: correcting optical distortion, correcting wide-angle distortion, and adapting to different subject types through selective application
3Object-affected harmful factors
If image conversion processing is applied to correct distortion, then distortion is reduced, but processing time and computational complexity increase
Solution Approach 1:
The patent creates distortion correction tables in advance that contain pre-calculated transformation parameters for different distortion conditions. During actual image processing, the system only needs to lookup and apply the pre-prepared transformation parameters rather than performing complex real-time calculations, significantly reducing processing time
Solution Approach 2:
The patent changes the approach from real-time complex distortion calculation to parameter lookup and application. By pre-calculating and storing distortion correction parameters in tables, the system transforms the computationally intensive real-time distortion correction into a faster parameter retrieval and application process
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
The apparatus produces images with reduced distortion, allowing for proper correction based on the subject type and conditions, effectively minimizing both optical and wide-angle distortion, thereby maintaining image quality and straight lines in digital captures.
Implementation Method 1
The distortion of image, on the other hand, is caused by distortion aberration. Since the distortion aberration is a phenomenon in which the incident light is more refracted with distance from a lens center
Implementation Method 2
The wide-angle distortion is a phenomenon that arises when a three-dimensional subject is projected through a lens onto a flat plane
Data Source
AI summary
A digital camera includes a distortion correction section, which is composed of a focal length determining section, a distortion evaluation section and a correction amount calculating section. The focal length determining section evaluates a focal length at the time of image capture. Based on the focal length, the distortion evaluation section evaluates the magnitude of wide-angle distortion and optical distortion in a captured image. Based on this evaluation, the distortion correction section selects an appropriate coefficient from an optical distortion correction coefficient table or a wide-angle distortion correction coefficient table. Using the selected coefficient, the correction amount calculating section applies a coordinate transform processing to cause positive or negative distortion to the captured image, and corrects the wide-angle distortion or the optical distortion.