opencv库中houghcircle函数中的dp参数究竟是如何工作的? [英] How exactly does the dp parameter in the houghcircle function in the opencv library work?
本文介绍了opencv库中houghcircle函数中的dp参数究竟是如何工作的?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我试图理解 .houghcircles() 函数，但我不完全理解 dp 影响结果.
查找 http:///i.imgur.com/iGyr7TG.jpg
提前致谢.
解决方案
Verba docent,
示例 trahunt.
最好在交互式 GUI 演示中看到
一个可配置的 UI 面板允许通过移动几个滑块来调整参数
<小时>导入系统导入简历2导入数学导入 numpy从 scipy.ndimage 导入标签pi_4 = 4*math.pidef nothing_asCallback(x):经过def GUI_openCV_circles():#-------------------------------------------------------------------------------------------GUI-<图像>frame = cv2.imread("openCV_CircleDetection_IMG_LASSO_AREA.JPG")演示 = 帧[:800,:800,:]#-------------------------------------------------------------------------------------------GUI-<window>-scv2.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 = 无 # .initaCanny_LoTreshold = 127aCanny_LoTreshold_PREVIOUS = -1aCanny_HiTreshold = 255aCanny_HiTreshold_PREVIOUS = -1aHough_dp = 1aHough_dp_PREVIOUS = -1aHough_minDistance = 10aHough_minDistance_PREVIOUS = -1aHough_param1_aCannyHiTreshold = 255aHough_param1_aCannyHiTreshold_PREVIOUS = -1aHough_param2_aCentreDetectTreshold = 20aHough_param2_aCentreDetectTreshold_PREVIOUS = -1aHough_minRadius = 10aHough_minRadius_PREVIOUS = -1aHough_maxRadius = 30aHough_maxRadius_PREVIOUS = -1#--------------------------------------------------------------------------------------------GUI-<ACTOR>-scv2.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) # 静态 ...#-------------------------------------------------------------------------------------------GUI-mainloop()打印 " - - - - - - - - - - - - - - - - - - - - - - - ---------------------------- 按[ESC]退出"而(真):#--------------------------------------------------------------------------------------------GUI-[ESCAPE]?如果 aKeyPRESSED == 27:休息#-------------------------------------------------------------------------------------------<vars>-DETECT-delta(s)aCanny_LoTreshold = cv2.getTrackbarPos("Lo_Treshold", "DEMO.Canny")aCanny_HiTreshold = cv2.getTrackbarPos("Hi_Treshold", "DEMO.Canny")如果(aCanny_LoTreshold ！= aCanny_LoTreshold_PREVIOUS或 aCanny_HiTreshold != aCanny_HiTreshold_PREVIOUS):# --------------------------= 标志aCannyRefreshFLAG = True# --------------------------= 重新同步aCanny_LoTreshold_PREVIOUS = aCanny_LoTresholdaCanny_HiTreshold_PREVIOUS = aCanny_HiTreshold别的:# --------------------------= 取消标记aCannyRefreshFLAG = FalseaHough_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")如果 ( aHough_dp != aHough_dp_PREVIOUS或 aHough_minDistance != aHough_minDistance_PREVIOUS或 aHough_param1_aCannyHiTreshold != aHough_param1_aCannyHiTreshold_PREVIOUS或 aHough_param2_aCentreDetectTreshold != aHough_param2_aCentreDetectTreshold_PREVIOUS或 aHough_minRadius != aHough_minRadius_PREVIOUS或 aHough_maxRadius != aHough_maxRadius_PREVIOUS):# --------------------------= 标志aHoughRefreshFLAG = True# ----------------------------------------------= RE-同步aHough_dp_PREVIOUS = aHough_dpaHough_minDistance_PREVIOUS = aHough_minDistanceaHough_param1_aCannyHiTreshold_PREVIOUS = aHough_param1_aCannyHiTresholdaHough_param2_aCentreDetectTreshold_PREVIOUS = aHough_param2_aCentreDetectTresholdaHough_minRadius_PREVIOUS = aHough_minRadiusaHough_maxRadius_PREVIOUS = aHough_maxRadius别的:# --------------------------= 取消标记aHoughRefreshFLAG = False#-------------------------------------------------------------------------------REFRESH-process-pipe-line ( 带有最近的 <state> <vars> )如果(aCannyRefreshFLAG):边缘 = cv2.Canny(演示，aCanny_LoTreshold，aCanny_HiTreshold)#-------------------------------------------------------------------------------------------GUI-SHOW-Canny()-<edges>-onRefreshFLAGcv2.imshow(DEMO.Canny"，边缘)经过如果(aCannyRefreshFLAG 或 aHoughRefreshFLAG):circles = cv2.HoughCircles(边缘，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>-onRefreshFLAGdemoWithCircles = cv2.cvtColor(demo, cv2.COLOR_BGR2RGB) # .re-init <<<<源代码demoWithCircles = cv2.cvtColor(demoWithCircles, cv2.COLOR_RGB2BGR)对于 aCircle in circles[0]:cv2.circle( demoWithCircles, ( int( aCircle[0] ), int( aCircle[1] ) ),圆[2]，(0,255,0),1)经过经过cv2.imshow("DEMO.Canny.Circles", demoWithCircles)经过#-------------------------------------------------------------------------------------------<vars>-UPDATE-<state># 参考.上面的 .onRefreshFLAG RE-SYNC 部分#--------------------------------------------------------------------------------------------GUI-INPUT ?[逃脱]aKeyPRESSED = cv2.waitKey(1) &0xFF经过#-------------------------------------------------------------------------------------------GUI-<window>-s/DESTROYcv2.destroyWindow("DEMO.IN")cv2.destroyWindow("DEMO.Canny")cv2.destroyWindow("DEMO.Canny.Circles")#-------------------------------------------------------------------------------------------GUI-<window>-s经过定义主():GUI_openCV_circles()返回 0如果 __name__ == '__main__':主要的()I'm trying to understand the .houghcircles() function and I'm not fully understanding how dp affects the results.
Looking up http://docs.opencv.org/modules/imgproc/doc/feature_detection.html?highlight=houghcircles#houghcircles, it says:
dp– Inverse ratio of the accumulator resolution to the image resolution.
For example,
ifdp=1, the accumulator has the same resolution as the input image.
Ifdp=2, the accumulator has half as big width and height.
Say you have a 1000x1000 image. You then set dp to 3, so the accumulator sees only 1/3 the image? Or is it something like, the image size remains the same but the number of pixels seen is less? i.e. ever 3 pixels in the original image correlate to 1 pixel that the accumulator sees, like the original image is "blurred"?
I've managed to detect accurately the number of red apples in a bowl by understanding the other parameters and then fiddling with dp.
Perhaps my understanding of the accumulator is incorrect as well since the two are correlated? From what I understand, it is the number of times a region is "hit", but I am not sure how it calculates a "hit region"
My code takes a bowl of apples, converts to HSV, grabs the reddish hues, converts it to either black or white (not greyscale format) using bitWiseOr, then do some .erode() / .dilate() to reduce noise, then .houghcircles().
My resulting image looks like this http://i.imgur.com/iGyr7TG.jpg
Thanks in advance.
解决方案
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()
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