// Copyright (C) 2014 Davis E. King (davis@dlib.net) // License: Boost Software License See LICENSE.txt for the full license. #undef DLIB_HOUGH_tRANSFORM_ABSTRACT_Hh_ #ifdef DLIB_HOUGH_tRANSFORM_ABSTRACT_Hh_ #include "../geometry.h" #include "../image_processing/generic_image.h" namespace dlib{// ---------------------------------------------------------------------------------------- classhough_transform{/*! WHAT THIS OBJECT REPRESENTS This object is a tool for computing the line finding version of the Hough transform given some kind of edge detection image as input. It also allows the edge pixels to be weighted such that higher weighted edge pixels contribute correspondingly more to the output of the Hough transform, allowing stronger edges to create correspondingly stronger line detections in the final Hough transform. THREAD SAFETY It is safe for multiple threads to make concurrent accesses to this object without synchronization. !*/ public: explicithough_transform(unsignedlongsize_ ); /*! requires - size_ > 0 ensures - This object will compute Hough transforms that are size_ by size_ pixels. This is in terms of both the Hough accumulator array size as well as the input image size. - #size() == size_ !*/unsignedlongsize( ) const; /*! ensures - returns the size of the Hough transforms generated by this object. In particular, this object creates Hough transform images that are size() by size() pixels in size. !*/longnr( ) const; /*! ensures - returns size() !*/longnc( ) const; /*! ensures - returns size() !*/ std::pair<point, point>get_line( const point& p ) const; /*! requires - rectangle(0,0,size()-1,size()-1).contains(p) == true (i.e. p must be a point inside the Hough accumulator array) ensures - returns the line segment in the original image space corresponding to Hough transform point p. - The returned points are inside rectangle(0,0,size()-1,size()-1). !*/ template < typename image_type > pointget_best_hough_point( const point& p, const image_type& himg ); /*! requires - image_type == an image object that implements the interface defined in dlib/image_processing/generic_image.h and it must contain grayscale pixels. - himg.nr() == size() - himg.nc() == size() - rectangle(0,0,size()-1,size()-1).contains(p) == true ensures - This function interprets himg as a Hough image and p as a point in the original image space. Given this, it finds the maximum scoring line that passes though p. That is, it checks all the Hough accumulator bins in himg corresponding to lines though p and returns the location with the largest score. - returns a point X such that get_rect(himg).contains(X) == true !*/ template < typename in_image_type, typename out_image_type >voidoperator() ( const in_image_type& img, const rectangle& box, out_image_type& himg ) const; /*! requires - in_image_type == an image object that implements the interface defined in dlib/image_processing/generic_image.h and it must contain grayscale pixels. - out_image_type == an image object that implements the interface defined in dlib/image_processing/generic_image.h and it must contain grayscale pixels. - box.width() == size() - box.height() == size() ensures - Computes the Hough transform of the part of img contained within box. In particular, we do a grayscale version of the Hough transform where any non-zero pixel in img is treated as a potential component of a line and accumulated into the Hough accumulator #himg. However, rather than adding 1 to each relevant accumulator bin we add the value of the pixel in img to each Hough accumulator bin. This means that, if all the pixels in img are 0 or 1 then this routine performs a normal Hough transform. However, if some pixels have larger values then they will be weighted correspondingly more in the resulting Hough transform. - #himg.nr() == size() - #himg.nc() == size() - #himg is the Hough transform of the part of img contained in box. Each point in #himg corresponds to a line in the input box. In particular, the line for #himg[y][x] is given by get_line(point(x,y)). Also, when viewing the #himg image, the x-axis gives the angle of the line and the y-axis the distance of the line from the center of the box. !*/};}#endif // DLIB_HOUGH_tRANSFORM_ABSTRACT_Hh_