Hof transformation is a method for finding straight lines, circles, and other simple shapes in an image. Hof line transformation is to find a straight line in a binary image by using Hof transformation.
Using cv_hough_probabilistic, corresponding to ppht (cumulative probability Hof transformation )? The specific implementation of this algorithm is to be further explored !!!
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The HOF line transformation function is:
Houghlines
Finding a straight line in a binary image using the Hough Transform
CvSeq* cvHoughLines2( CvArr* image, void* line_storage, int method, double rho, double theta, int threshold, double param1=0, double param2=0 );
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Image
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Input an 8-bit, single-channel (Binary) image. When the cv_hough_probabilistic method is used to detect the image, its content is changed by the function.
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Line_storage
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The detected Line Segment Storage warehouse. it can be a memory storage warehouse (in this case, a line segment sequence is created in the storage warehouse and returned by the function) or a special type that contains line segment parameters (see below) has a single row/single column matrix (cvmat *). The matrix header is modified by the function so that its Cols/rows contains a group of detected line segments. If line_storage is a matrix, and the actual number of line segments exceeds the matrix size, the maximum number of lines may be returned (for standard Hough transformation, the line segments are output in descending order of length ).
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Method
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One of the following variables is the Hough variable:
- Cv_hough_standard-traditional or standard Hough transformation. each line segment is represented by two floating point numbers (p, θ), where p is the distance between the line and the origin (0, 0), and the angle between the θ line segment and the x-axis. Therefore, the matrix type must be cv_32fc2 type.
- Cv_hough_probabilistic-probabilistic Hough Transformation (if the image contains long linear segmentation, it is more efficient). It returns the line segment instead of the entire line segment. Each split is expressed by the start and end points. Therefore, the matrix (or the sequence created) type is cv_32sc4.
- Cv_hough_multi_scale-multi-scale variant of the traditional hough transformation. The line segment is encoded in the same way as cv_hough_standard.
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Rock
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Distance Precision of pixel-related units
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Theta
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Angle accuracy of radian Measurement
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Threshold
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Threshold parameter. If the cumulative value is greater than threshold, the line segment returned by the function.
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Param1
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Parameters related to the first method:
- Do not use (0) for traditional Hough transformations ).
- This is the minimum line segment length.
- For the multi-scale hough transformation, it is the denominator of the Distance Precision, and the approximate distance precision is, and the precise precision should be ).
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Param2
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Parameters related to the second method:
- Do not use (0) for traditional Hough transformations ).
- This parameter indicates the maximum gap between broken line segments in the same line ), that is, when the interval between two broken lines in the same line is less than param2, combine them into one.
- For multi-scale hough transformation, it is the denominator of angle precision theta (the approximate angle precision is Theta, and the precise angle should be Theta/param2 ).
The cvhoughlines2 function implements different methods for Line Segment Detection. Example.
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/* Code */
Cvcvtcolor color space conversion is used in the program to convert the input image from a color space to another color space. The system uses a single-channel image, which is then converted to a three-channel image, and then uses the Hough transformation.
# Include
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/* Result */
SRC
Hough line
As shown in the figure, green lines are used to sketch all the straight lines after being detected by the canny contour, and then transformed by the Hough line.
