Keystone Correction via Line Rotation and Shift
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image processing methods for correcting perspective distortion in projected images, such as keystone correction, are complex and prone to errors when the projector is not aligned frontally with the projection surface, requiring multiple steps and knowledge of the projection angle, especially when the surface is rotated or tilted.
Innovation Solution
An image processing method where individual image lines are rotated and/or shifted to align with the projection surface, maintaining the orientation of other lines, allowing for intuitive keystone correction without needing to know the projection angle or distance, and enabling correction of perspective distortions by varying the length distribution of image line sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional keystone correction methods are used to correct perspective distortion, then the projected image can be corrected, but the process becomes complex and prone to errors when the projector is not aligned frontally with the projection surface
Solution Approach 1:
The patent segments the image correction process by treating each image line independently. Instead of applying complex global transformation matrices, the method processes each horizontal image line separately, rotating and shifting them individually to align with the projection surface. This segmentation simplifies the correction process while maintaining accuracy for non-frontal projector orientations.
Solution Approach 2:
The patent inverts the traditional approach by not calculating how to transform the image to match the distorted projection, but rather how to rotate and shift each image line to directly align with the projection surface edges. This inversion of the problem-solving approach simplifies the correction process and eliminates the need for complex angle measurements.
2Manufacturing precision
If multiple correction steps are applied to achieve proper alignment, then the perspective distortion can be corrected, but the process requires excessive time and multiple operations
Solution Approach 1:
The patent performs preliminary action by directly rotating and shifting each image line to its final aligned position in a single operation. Instead of applying multiple sequential correction steps, the method calculates the required rotation and shift for each line and applies them simultaneously, achieving proper alignment in one pass through the image data.
3Measurement precision
If the projection angle and distance are measured precisely, then accurate keystone correction can be achieved, but the measurement process becomes complex and difficult
Solution Approach 1:
The patent extracts the essential alignment information directly from the projection surface edges rather than measuring the projection angle and distance. By taking out only the necessary geometric information (edge positions and orientations) from the complex measurement problem, the method achieves accurate correction without requiring precise angle and distance measurements.
4Adaptability or versatility
If the projector is placed in a non-frontal orientation, then flexibility in projection positioning is improved, but perspective distortion occurs in the projected image
Solution Approach 1:
The patent applies dynamics by making the image line rotation and shift amounts variable for each line based on its position in the image. Instead of applying a uniform correction, the method dynamically adjusts the rotation and shift parameters for each image line to compensate for the perspective distortion caused by non-frontal projector orientation, thereby maintaining image accuracy while preserving positioning flexibility.
Data Source
AI summary
For keystone correction of the perspective distortion of an image (18) projected onto a projection surface (12), an image existing in electronic form is processed by a processing device to reverse the perspective distortion. For this purpose, the processing device, respectively rotates and shifts exactly one image line (36) at a time, respectively, while the orientation of the other image lines (40,42,46) is maintained fixed. In addition or alternately, the image lines (36,40,42,46) of the original electronic image comprise a plurality of partial sections of equal lengths which are differently stretched and/or compressed by the processing device. Subsequently, the image is newly computed under consideration of all of the image lines (36,40,42,46) and is projected onto a projection surface (12) by a projector.