How exactly does the dp parameter in the houghcircle function in the opencv library work?
I\'m trying to understand the .houghcircles() function and I\'m not fully understanding how dp affects the result
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Verba docent,
Exempla trahunt.Best seen on an interactive GUI-Demo
A configurable UI-panel allows to adjust parameter(s) by moving a few sliders
import sys import cv2 import math import numpy from scipy.ndimage import label pi_4 = 4*math.pi def nothing_asCallback(x): pass def GUI_openCV_circles(): # --------------------------------------------------------------------------------GUI-<image> frame = cv2.imread( "openCV_CircleDetection_IMG_LASSO_AREA.JPG" ) demo = frame[:800,:800,:] # --------------------------------------------------------------------------------GUI-<window>-s cv2.namedWindow( "DEMO.IN", cv2.cv.CV_WINDOW_AUTOSIZE ) cv2.namedWindow( "DEMO.Canny", cv2.cv.CV_WINDOW_AUTOSIZE ) cv2.namedWindow( "DEMO.Canny.Circles", cv2.cv.CV_WINDOW_AUTOSIZE ) # --------------------------------------------------------------------------------GUI-<state>-initial-value(s) aKeyPRESSED = None # .init aCanny_LoTreshold = 127 aCanny_LoTreshold_PREVIOUS = -1 aCanny_HiTreshold = 255 aCanny_HiTreshold_PREVIOUS = -1 aHough_dp = 1 aHough_dp_PREVIOUS = -1 aHough_minDistance = 10 aHough_minDistance_PREVIOUS = -1 aHough_param1_aCannyHiTreshold = 255 aHough_param1_aCannyHiTreshold_PREVIOUS = -1 aHough_param2_aCentreDetectTreshold = 20 aHough_param2_aCentreDetectTreshold_PREVIOUS = -1 aHough_minRadius = 10 aHough_minRadius_PREVIOUS = -1 aHough_maxRadius = 30 aHough_maxRadius_PREVIOUS = -1 # --------------------------------------------------------------------------------GUI-<ACTOR>-s cv2.createTrackbar( "Lo_Treshold", "DEMO.Canny", aCanny_LoTreshold, 255, nothing_asCallback ) cv2.createTrackbar( "Hi_Treshold", "DEMO.Canny", aCanny_HiTreshold, 255, nothing_asCallback ) cv2.createTrackbar( "dp", "DEMO.Canny.Circles", aHough_dp, 255, nothing_asCallback ) cv2.createTrackbar( "minDistance", "DEMO.Canny.Circles", aHough_minDistance, 255, nothing_asCallback ) cv2.createTrackbar( "param1_HiTreshold", "DEMO.Canny.Circles", aHough_param1_aCannyHiTreshold, 255, nothing_asCallback ) cv2.createTrackbar( "param2_CentreDetect", "DEMO.Canny.Circles", aHough_param2_aCentreDetectTreshold, 255, nothing_asCallback ) cv2.createTrackbar( "minRadius", "DEMO.Canny.Circles", aHough_minRadius, 255, nothing_asCallback ) cv2.createTrackbar( "maxRadius", "DEMO.Canny.Circles", aHough_maxRadius, 255, nothing_asCallback ) cv2.imshow( "DEMO.IN", demo ) # static ... # --------------------------------------------------------------------------------GUI-mainloop() print " --------------------------------------------------------------------------- press [ESC] to exit " while( True ): # --------------------------------------------------------------------------------GUI-[ESCAPE]? if aKeyPRESSED == 27: break # --------------------------------------------------------------------------------<vars>-DETECT-delta(s) aCanny_LoTreshold = cv2.getTrackbarPos( "Lo_Treshold", "DEMO.Canny" ) aCanny_HiTreshold = cv2.getTrackbarPos( "Hi_Treshold", "DEMO.Canny" ) if ( aCanny_LoTreshold != aCanny_LoTreshold_PREVIOUS or aCanny_HiTreshold != aCanny_HiTreshold_PREVIOUS ): # --------------------------= FLAG aCannyRefreshFLAG = True # --------------------------= RE-SYNC aCanny_LoTreshold_PREVIOUS = aCanny_LoTreshold aCanny_HiTreshold_PREVIOUS = aCanny_HiTreshold else: # --------------------------= Un-FLAG aCannyRefreshFLAG = False aHough_dp = cv2.getTrackbarPos( "dp", "DEMO.Canny.Circles" ) aHough_minDistance = cv2.getTrackbarPos( "minDistance", "DEMO.Canny.Circles" ) aHough_param1_aCannyHiTreshold = cv2.getTrackbarPos( "param1_HiTreshold", "DEMO.Canny.Circles" ) aHough_param2_aCentreDetectTreshold = cv2.getTrackbarPos( "param2_CentreDetect","DEMO.Canny.Circles" ) aHough_minRadius = cv2.getTrackbarPos( "minRadius", "DEMO.Canny.Circles" ) aHough_maxRadius = cv2.getTrackbarPos( "maxRadius", "DEMO.Canny.Circles" ) if ( aHough_dp != aHough_dp_PREVIOUS or aHough_minDistance != aHough_minDistance_PREVIOUS or aHough_param1_aCannyHiTreshold != aHough_param1_aCannyHiTreshold_PREVIOUS or aHough_param2_aCentreDetectTreshold != aHough_param2_aCentreDetectTreshold_PREVIOUS or aHough_minRadius != aHough_minRadius_PREVIOUS or aHough_maxRadius != aHough_maxRadius_PREVIOUS ): # --------------------------= FLAG aHoughRefreshFLAG = True # ----------------------------------------------= RE-SYNC aHough_dp_PREVIOUS = aHough_dp aHough_minDistance_PREVIOUS = aHough_minDistance aHough_param1_aCannyHiTreshold_PREVIOUS = aHough_param1_aCannyHiTreshold aHough_param2_aCentreDetectTreshold_PREVIOUS = aHough_param2_aCentreDetectTreshold aHough_minRadius_PREVIOUS = aHough_minRadius aHough_maxRadius_PREVIOUS = aHough_maxRadius else: # --------------------------= Un-FLAG aHoughRefreshFLAG = False # --------------------------------------------------------------------------------REFRESH-process-pipe-line ( with recent <state> <vars> ) if ( aCannyRefreshFLAG ): edges = cv2.Canny( demo, aCanny_LoTreshold, aCanny_HiTreshold ) # --------------------------------------------------------------------------------GUI-SHOW-Canny()-<edges>-onRefreshFLAG cv2.imshow( "DEMO.Canny", edges ) pass if ( aCannyRefreshFLAG or aHoughRefreshFLAG ): circles = cv2.HoughCircles( edges, cv2.cv.CV_HOUGH_GRADIENT, aHough_dp, aHough_minDistance, param1 = aHough_param1_aCannyHiTreshold, param2 = aHough_param2_aCentreDetectTreshold, minRadius = aHough_minRadius, maxRadius = aHough_maxRadius ) # --------------------------------------------------------------------------------GUI-SHOW-HoughCircles()-<edges>-onRefreshFLAG demoWithCircles = cv2.cvtColor( demo, cv2.COLOR_BGR2RGB ) # .re-init <<< src demoWithCircles = cv2.cvtColor( demoWithCircles, cv2.COLOR_RGB2BGR ) for aCircle in circles[0]: cv2.circle( demoWithCircles, ( int( aCircle[0] ), int( aCircle[1] ) ), aCircle[2], (0,255,0), 1 ) pass pass cv2.imshow( "DEMO.Canny.Circles", demoWithCircles ) pass # --------------------------------------------------------------------------------<vars>-UPDATE-<state> # ref. above in .onRefreshFLAG RE-SYNC sections # --------------------------------------------------------------------------------GUI-INPUT ? [ESCAPE] aKeyPRESSED = cv2.waitKey(1) & 0xFF pass # --------------------------------------------------------------------------------GUI-<window>-s / DESTROY cv2.destroyWindow( "DEMO.IN" ) cv2.destroyWindow( "DEMO.Canny" ) cv2.destroyWindow( "DEMO.Canny.Circles" ) # --------------------------------------------------------------------------------GUI-<window>-s pass def main(): GUI_openCV_circles() return 0 if __name__ == '__main__': main()讨论(0)
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