Whiteboard Image Correction and Speaker Removal
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Solution Overview
Problem
Current methods of recording classroom lectures or presentations are limited by geometric distortion, poor acquisition conditions, and obstruction by the speaker, resulting in difficult-to-interpret visual signals, which restrict the visual and educational experience.
Innovation Solution
A method that involves detecting the boundaries of a whiteboard image in video frames, classifying them, forming quadrangles, identifying the most likely whiteboard areas, cropping those areas, correcting perspective, and enhancing colors, while also implementing an algorithm to remove the speaker from the frame, allowing for improved visualization of the whiteboard image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If simple video recording is used to capture the lecture scene, then the recording process is simple, but the visual signal is hard to interpret due to geometric distortion, poor acquisition conditions, and speaker obstruction
Solution Approach 1:
The patent extracts the whiteboard image from the complex video scene by detecting whiteboard boundaries and cropping the region of interest. This separates the useful whiteboard content from the distracting elements like the speaker and poor acquisition conditions, directly improving visual interpretability while maintaining recording simplicity
Solution Approach 2:
The patent creates a corrected copy of the whiteboard image by applying perspective transformation to eliminate geometric distortion. This produces a clean, interpretable version of the whiteboard content without requiring changes to the original recording process
2Area of stationary object
If the speaker is included in the video frame, then the complete lecture scene is captured, but the whiteboard image becomes obscured and difficult to interpret
Solution Approach 1:
The patent extracts only the whiteboard region from the full video frame by detecting whiteboard boundaries and cropping. This removes the speaker and other obstructing elements while preserving the complete whiteboard content, directly resolving the conflict between frame coverage and whiteboard visibility
3Manufacturing precision
If perspective correction is applied to the whiteboard image, then geometric distortion is eliminated, but additional processing steps are required
Solution Approach 1:
The patent performs perspective correction as a preliminary processing step immediately after whiteboard detection and cropping. By applying the transformation early in the processing pipeline, the system establishes geometric accuracy for all subsequent operations without requiring complex iterative corrections later
Data Source
AI summary
A method, system and computer program product for improving the recording of classroom lectures or other such presentations. A video frame containing a whiteboard image is converted into a black and white image for the detection of boundaries. These boundaries are classified as horizontal or vertical lines. Quadrangles are then formed using spatial arrangements of these lines. The quadrangles that are most likely to spatially coincide with the boundaries of the whiteboard image are identified. The quadrangles are then sorted (ranked) based on specific characteristics, such as size and position. The area corresponding to the identified quadrangle in the video frame is then cropped. Furthermore, the speaker in the video frame can be removed based on detecting changes that are characteristic of movements of a speaker. In this manner, the visual and educational experience involved in the recording of classroom lectures or other such presentation is improved.