Quadrangle Area Extraction via Line Segment Likelihood Ranking
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Solution Overview
Problem
Conventional image capturing devices face challenges in extracting a quadrangle area including a subject contour from images, especially when the size of the quadrangle area is unknown or when multiple subject images are present in a single image, leading to inadequate extraction and user selection difficulties due to switching between incorrect rectangle candidates.
Innovation Solution
An image processing apparatus that detects vertical and horizontal line segments, generates facing-lines candidates, and calculates the likelihood of rectangle candidates based on the relationship between line segments, allowing for smooth user selection by displaying candidates in descending order of likelihood and preventing switching between different subject images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of edge pixels on each detected straight line is calculated and straight lines are selected according to the largeness of the calculated numbers, then the quadrangle area can be extracted using a simple method, but an inadequate quadrangle area may be extracted when the size of the quadrangle area is unknown or multiple subject images exist in one image
Solution Approach 1:
The patent changes the evaluation parameter from simple edge pixel count to a comprehensive likelihood value that considers multiple factors including edge pixel distribution, line segment relationships, and geometric constraints. This allows accurate extraction of quadrangle areas of various sizes and handles multiple subject images effectively.
Solution Approach 2:
The patent introduces line segments as an intermediary element between edge pixels and quadrangle area selection. By detecting line segments from edge pixels and evaluating their relationships, the system achieves more accurate quadrangle area extraction while maintaining computational efficiency.
2Adaptability or versatility
If multiple rectangle candidates are displayed on the display screen in descending order of the evaluation value and the user selects a rectangle candidate, then the user can choose from multiple options, but the user cannot select a rectangle candidate smoothly because of phenomena that a displayed rectangle candidate is switched between different subject images and that another rectangle candidate is displayed for a subject image for which a rectangle candidate has already been selected
Solution Approach 1:
The patent implements a feedback mechanism where the system monitors the user's selection state and provides appropriate feedback by controlling the display of rectangle candidates. When a rectangle candidate is selected, the system provides visual feedback by changing its display state and prevents redundant selections, enabling smooth user operation.
Solution Approach 2:
The patent dynamically controls the display state of rectangle candidates based on user interaction. The display updates adaptively to reflect selection status, hiding already-selected candidates and highlighting selectable ones, which creates a smooth user experience when handling multiple subject images.
3Measurement precision
If straight lines are detected using Hough transform and edge images are processed, then the subject contour can be represented, but the processing complexity increases and inadequate extraction occurs when size is unknown
Solution Approach 1:
The patent segments the edge image into multiple line segments with specific attributes (position, length, orientation). By dividing the continuous edge detection task into discrete line segment elements, the system reduces processing complexity while maintaining accurate subject contour representation.
Solution Approach 2:
The patent extracts only the essential features (line segments with key attributes) from the edge image, discarding redundant information. This extraction approach simplifies subsequent processing while preserving the necessary information for accurate quadrangle area detection.
Data Source
AI summary
An image processing apparatus includes: a line segment detecting unit configured to detect vertical line segments and horizontal line segments in an image; a facing-lines candidate generating unit configured to generate vertical and horizontal facing-lines candidates from the vertical and horizontal line segments, the vertical and horizontal facing-lines candidates being candidates for pairs of facing lines configuring quadrangle areas in the image; a rectangle candidate generating unit configured to generate a plurality of pairs of one of the vertical facing-lines candidates and one of the horizontal facing-lines candidates, and to generate the quadrangle areas as rectangle candidates; and a calculating unit configured to calculate likelihood of each of the rectangle candidates based on a relationship between line segments constituting the vertical facing-lines candidates and the horizontal facing-lines candidates and the rectangle candidates.