Automatic Keystone Correction via Focusing Zone Analysis
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Solution Overview
Problem
Existing projection systems require manual adjustment and additional components for keystone correction, which is inefficient and impractical, especially when projectors are tilted due to space constraints, and current distance measurement methods are inadequate for practical applications.
Innovation Solution
A projection system comprising a projector with a stepper motor-driven lens module, an image capturing device, and a processor that divides the captured image into focusing zones, adjusts focus for maximum clarity, calculates included angles, and performs warping operations to correct keystone distortions automatically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual adjustment is used for keystone correction, then the projection image can be corrected to a rectangle, but the operation efficiency is low and requires visual judgment
Solution Approach 1:
The system performs automatic keystone correction by capturing the projection image, calculating distortion parameters, and adjusting the image accordingly without requiring manual user intervention. The projector automatically detects the trapezoidal distortion and applies the necessary correction transformations.
Solution Approach 2:
The patent replaces manual visual judgment and mechanical adjustment with an automated image processing system that uses algorithms to detect trapezoidal distortion and calculate correction parameters, substituting human operation with computational methods.
2Extent of automation
If additional distance measuring modules are added for automatic keystone correction, then automation is improved, but the device size increases and may not fit small projectors
Solution Approach 1:
The projector's existing image capturing device (such as a camera or sensor) is made multi-functional by using it both for normal projection monitoring and for keystone correction detection. This eliminates the need for separate distance measuring modules while maintaining automatic correction capability.
Solution Approach 2:
The patent combines the keystone correction function with the projector's existing imaging components. The same image capture device used for displaying content is also utilized to detect the projection image geometry and trigger automatic correction, merging multiple functions into a single integrated system.
3Measurement precision
If laser modules are used for distance measurement, then measurement precision is improved, but the measurement range is too short for practical projector distances
Solution Approach 1:
Instead of measuring distance directly along the optical axis (one-dimensional measurement), the system captures a two-dimensional image of the projection and uses image geometry analysis to infer distance and angle information. This dimensional shift allows measurement of longer distances using the same imaging components.
Data Source
AI summary
A projection system and a keystone correction method are provided. The projection system includes: a projector projecting an image to a projection zone; an image capturing device capturing a captured image including the projection zone; and a processor. The processor divides the captured image into multiple focusing zones, and controls a stepper motor to shift focusing on the focusing zones at edges to obtain a step of the stepper motor and a distance for each of the focusing zones with a maximum clarity value. The distance is a projection distance between a lens module and the focusing zone. The processor calculates an included angle between the direction of a light axis of the projector and the projection zone according to the distances of the focusing zones at the edges, and performs a warping operation on a projection image according to the included angle.