Keystone Correction via Line Buffer Segmentation
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Solution Overview
Problem
Existing digital projection systems face inefficiencies in keystone correction due to the need for costly frame buffers and high memory intensity when correcting keystone distortion caused by non-perpendicular projections, leading to slow processing and high costs.
Innovation Solution
A method that predistorts the video image by processing only a small number of video lines at a time, using a keystone controller to horizontally and vertically scale the image, reducing memory requirements and improving processing efficiency by building up a predistorted output frame sequentially.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If horizontal or vertical scaling is applied to correct keystone distortion, then image distortion is corrected, but memory usage increases significantly requiring costly frame buffers
Solution Approach 1:
The patent divides the image into multiple scan lines and processes them sequentially rather than loading the entire image into memory. The frame buffer is segmented into smaller line buffers that are processed one at a time, dramatically reducing the memory required for keystone correction while maintaining the ability to correct distortion across the entire image.
2Manufacturing precision
If frame buffer is used for keystone correction processing, then image scaling can be performed, but processing speed decreases and costs increase
Solution Approach 1:
The patent pre-calculates the horizontal and vertical scaling factors based on the desired keystone correction parameters before processing begins. This preliminary calculation allows the processing stage to simply apply the pre-determined scaling factors to each scan line, significantly speeding up the actual correction process while maintaining accurate scaling.
3Manufacturing precision
If entire frame is processed simultaneously for keystone correction, then correction accuracy is maintained, but processing time increases
Solution Approach 1:
The patent processes the image in periodic increments by handling one scan line at a time in sequence rather than attempting to process the entire frame simultaneously. This periodic processing approach maintains correction accuracy for each line while dramatically reducing the time required compared to simultaneous full-frame processing.
Data Source
AI summary
We describe a keystone correction system and method. A vertical scalar vertically scales an input image and stores the results to a line buffer. A horizontal scalar retrieves the stored results from the line buffer and horizontally scales the stored results using the relatively small number of lines from the line buffer. The system repeats the vertically scaling, storing, and horizontal scaling until it processes all input image lines.