Touch-Based Keystone Correction for Projectors
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Solution Overview
Problem
Existing keystone correction methods for multimedia projectors, which rely on camera-assisted approaches, fail when camera vision cannot accurately detect the projecting area due to hardware issues or reduced ambient light conditions, preventing proper image alignment.
Innovation Solution
A touch-input based keystone correction technique that projects an image onto a touch screen, uses perspective transformations to modify the image's size and shape, and receives touch signals to align the image corners, allowing for accurate resizing and reshaping without camera detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If camera-assisted keystone correction is used, then image alignment can be achieved under ideal conditions, but the system fails when camera detection is unreliable due to hardware issues or lighting conditions
Solution Approach 1:
The patent removes the camera component from the keystone correction system entirely. Instead of using camera-assisted detection, the system projects test patterns onto the display surface and uses a separate sensing mechanism (such as ambient light sensors or touch screen controllers) to detect the projected pattern coordinates. This extraction of the camera function eliminates the reliability issues associated with camera detection while maintaining the ability to perform perspective transformation.
Solution Approach 2:
The patent introduces an intermediary sensing mechanism that detects the projected test patterns without requiring camera vision. This intermediary system (such as ambient light sensors or touch screen controllers) acts as a mediator between the projected image and the processing system, enabling reliable coordinate detection under various lighting conditions without the vulnerabilities of camera-based approaches.
2Extent of automation
If camera-assisted approaches are used for keystone correction, then automatic detection is possible, but the system becomes vulnerable to hardware issues and ambient light conditions
Solution Approach 1:
The system performs self-calibration by projecting test patterns and automatically detecting them using its own sensing mechanisms. The projector system uses its embedded sensors (ambient light sensors or touch screen controllers) to detect the projected patterns, eliminating dependence on external camera systems. This self-service approach maintains automation while improving reliability by using the system's own components for detection.
3Device complexity
If touch screen controllers are used for detection instead of cameras, then hardware complexity is reduced, but the system requires a touch screen interface
Solution Approach 1:
The patent leverages the multi-functionality of touch screen controllers, which serve both as the display surface for projection and as the detection mechanism. The same touch screen controller that manages touch input also detects the projected test pattern coordinates, eliminating the need for separate camera hardware. This universal approach reduces hardware complexity while the system maintains adaptability by working specifically with touch screen surfaces.
Data Source
AI summary
An example calibration device includes a projector to project a first image onto a touch screen. The first image includes a first set of four corner coordinates. A processor is to perform a first perspective transformation of the first image into a second image for projection onto the touch screen by the projector. The second image includes a second set of four corner coordinates. The processor is to receive at least one touch signal associated with a second set of four corner coordinates associated with the second image from the touch screen. The processor is to perform a second perspective transformation of the second image using the second set of four corner coordinates to resize the second image based on the first set of four corner coordinates.