Projection Device Keystone Correction via Trapezoidal Scaling
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Solution Overview
Problem
Projection devices often suffer from keystone distortion when the lens optical axis is not perpendicular to the projection surface, leading to reduced projection quality, and existing methods for correction are either costly or complex.
Innovation Solution
A projection device and method that utilize image processing to perform keystone correction by obtaining target coordinates, creating trapezoidal boundaries, and applying directional scaling to align the original image with a target quadrilateral boundary, thereby projecting a rectangular image without distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual adjustment of projection device placement is performed, then keystone distortion can be reduced, but it requires precise manual positioning and cannot adapt to environmental restrictions
Solution Approach 1:
The patent applies preliminary action by performing image pre-distortion processing before projection. The image processing chip预先 processes the image data to compensate for keystone distortion, so that when the distorted image is projected, it automatically corrects to form a rectangular projection image without requiring manual device adjustment.
Solution Approach 2:
The patent replaces the mechanical adjustment system with an image processing system. Instead of manually adjusting the projection device placement (mechanical approach), the system uses an image processing chip to perform digital pre-distortion processing, substituting mechanical positioning with digital image processing to achieve keystone correction.
2Manufacturing precision
If image pre-distortion processing is performed to achieve keystone correction, then projection quality is improved, but the processing complexity and cost increase
Solution Approach 1:
The patent applies segmentation by dividing the keystone correction process into two sequential scaling operations: horizontal direction scaling and vertical direction scaling. The image processing chip first performs scaling in one direction, then performs scaling in the perpendicular direction, breaking down the complex pre-distortion processing into simpler, more manageable steps that reduce processing complexity.
Data Source
AI summary
A projection device and a projection image correction method are provided. Four target coordinates of four target vertices forming a target quadrilateral boundary are obtained. A first trapezoidal boundary is obtained according to a predetermined image boundary and a first coordinate component of each of the four target coordinates. At least one edge of the target quadrilateral boundary is extended until intersecting with at least one of two reference line segments to obtain a second trapezoidal boundary. Bases of the first trapezoidal boundary are perpendicular to bases of the second trapezoidal boundary. First direction scaling processing is performed according to the first trapezoidal boundary, and second direction scaling processing is performed according to the second trapezoidal boundary, to scale an original image into a target image block aligned with the target quadrilateral boundary in an output image. The projection device projects the output image to display a rectangular projection image.