Document Camera Projective Transformation for Oblique View Correction
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Solution Overview
Problem
Conventional document cameras struggle with capturing clear images of three-dimensional objects from oblique angles, leading to edge truncation and distortion, which complicates image processing and projection, making it difficult for viewers to see the projected image effectively.
Innovation Solution
An imaging apparatus with a shape acquiring unit, correction parameter acquiring unit, and image effect processing unit that determines the contour and shape of the original object, corrects image effects using projection parameters, and performs image processing to cut out and transform the image for optimal projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the camera shoots the original from an oblique direction, then the camera can capture three-dimensional objects, but the edge of the original goes out of the view angle and the zoom magnification has to be reduced
Solution Approach 1:
The patent introduces a new dimension of processing by performing projective transformation on the captured image. This transformation corrects the perspective distortion caused by oblique shooting, effectively recovering the original proportions and edges that were lost in the 2D projection, thus resolving the contradiction between capturing 3D objects and maintaining measurement precision
Solution Approach 2:
The patent changes the parameter of image representation by applying projective transformation parameters. This transformation adjusts the geometric parameters of the image to correct distortion, allowing the system to maintain high zoom magnification while capturing oblique views of three-dimensional objects
2Shape
If the zoom magnification is reduced to avoid edge truncation, then the entire original fits in the view angle, but the ratio of the area of the original to the total area of the picked-up image is reduced
Solution Approach 1:
The patent performs projective transformation as a preliminary action on the captured image before further processing or projection. This pre-correction ensures that the entire original is properly represented in the corrected image with optimal area ratio, eliminating the need to reduce zoom magnification to avoid edge truncation
3Ease of manufacture
If the image containing unnecessary parts is processed for luminance and color difference, then image effects are improved, but the image is improperly processed and viewers find difficulty in viewing the projected image
Solution Approach 1:
The patent extracts only the necessary parts of the original image by applying projective transformation to isolate and correct the region of interest. This extraction removes unnecessary parts that would otherwise contaminate the image processing, ensuring that luminance and color difference processing is applied only to relevant areas, thus maintaining both ease of processing and reliability of the final image
Data Source
AI summary
A document camera has an image processing apparatus, which acquires the contour of an image of an original by means of a Roberts filter. The image processing apparatus detects straight lines as candidates for forming an image of the original from the acquired contour and acquires the shape of a quadrangle of the original. The image processing apparatus determines the projection parameters showing the relationship between the shape of the image of the original and the shape of the actual original from the positions of the corners of the quadrangle and executes an operation of projection/transformation on the image of the original. The document camera outputs the image data of the image to a projector, which projects an image of the original on a screen according to the image data.