Projection Position Adjustment Using Sub-Pixel Boundary Detection
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Solution Overview
Problem
Existing image projection systems face challenges in accurately adjusting the projection position of multiple images, particularly when the resolution of the camera is lower than the projector, leading to difficulties in maintaining adjustment accuracy and handling increased resolution.
Innovation Solution
The system employs an image processing apparatus with an acquisition unit, projection control unit, and adjusting unit, which projects pattern images with boundaries to compare output values from an image sensor, allowing precise adjustment of the projection position in units smaller than the pixel size by using reference pixels and patterns like checker patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the camera resolution is lower than the projector resolution, then the system can use lower-cost imaging equipment, but the adjustment precision of projection position deteriorates
Solution Approach 1:
The patent divides the projection adjustment process into two distinct phases: a rough adjustment phase using low-resolution camera feedback, and a fine adjustment phase using sub-pixel interpolation calculations. This segmentation allows the system to use inexpensive low-resolution cameras while achieving high precision through computational methods in the second phase.
Solution Approach 2:
The patent performs preliminary rough adjustment using the low-resolution camera to bring the projection position close to the target. This preliminary action establishes a starting point that is sufficiently near to the final position, enabling subsequent fine adjustment through sub-pixel interpolation to achieve the required precision without needing high-resolution camera hardware.
2Ease of operation
If traditional color information-based adjustment methods are used, then the adjustment process is simple, but the adjustment accuracy deteriorates due to color information changes
Solution Approach 1:
The patent extracts only the brightness information from the captured projection image, deliberately excluding color information from the adjustment calculation. By taking out only the necessary brightness data and ignoring color variations, the system achieves high precision adjustment without being affected by color information changes, while maintaining operational simplicity.
Solution Approach 2:
The patent changes the parameter used for adjustment from color information to brightness information. This parameter change makes the adjustment process immune to color variations and lighting conditions that would otherwise affect accuracy, while the brightness-based approach remains computationally simple and easy to implement.
3Productivity
If the projection position is adjusted in large increments, then the adjustment process is faster, but the final adjustment accuracy deteriorates
Solution Approach 1:
The patent segments the adjustment process into two stages with different step sizes: a first stage with large adjustment increments for rapid convergence toward the target position, and a second stage with sub-pixel level increments for precise final positioning. This segmentation enables the system to achieve both high speed and high accuracy by optimizing the step size for each phase of the adjustment process.
Solution Approach 2:
The patent dynamically adjusts the increment size during the adjustment process. Initially, large increments are used to quickly approach the target position, and then the increment size is reduced to sub-pixel levels for fine-tuning. This dynamic adjustment of step size allows the system to optimize both the speed of convergence and the final positioning accuracy.
Data Source
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AI summary
It includes an acquisition unit that acquires output values of a plurality of pixels from an image sensor, the image sensor including the plurality of pixels, the plurality of pixels having a predetermined pixel size, and a projection control unit capable of causing a first projection apparatus to project a first pattern image, and causing a second projection apparatus to project a second pattern image with a distance smaller than the predetermined pixel size as a unit of movement of a projection position, the first pattern image including one or more boundaries that are boundaries between a bright section and a dark section, the second pattern image including one or more corresponding boundaries corresponding to the one or more boundaries. Further, the information processing apparatus includes a storage unit that stores, as a reference value, an output value of one or more predetermined reference pixels in which an image of the one or more boundaries is formed, the output value being acquired from the image sensor that picks up the first pattern image projected by the first projection apparatus, and an adjusting unit that adjusts the projection position by comparing, for each movement of the projection position, an output value of the one or more predetermined reference pixels and the stored reference value, the output value of the one or more predetermined reference pixels being acquired from the image sensor that picks up the second pattern image projected by the second projection apparatus while moving the projection position in units of the movement after the projection of the first pattern image is stopped.