opencv库中houghcircle函数中的dp参数究竟如何工作？ [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参数究竟如何工作？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
我想了解 .houghcircles（） 功能，但我不完全了解 dp 会影响结果。
查找 http： //i.imgur.com/iGyr7TG.jpg
提前感谢。
解决方案
Verba docent，
Exempla trahunt。
-Demo
可配置的UI面板允许通过移动几个滑块来调整参数
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----- -------------------------------------------------- --------------------按[ESC]退出
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
或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。圆）
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
）：
＃-------------------------- = 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<状态> < vars> ）
if（aCannyRefreshFLAG）：
edges = cv2.Canny（demo，aCanny_LoTreshold，
aCanny_HiTreshold
）
＃ -------------------------------------------------- ----------------------- GUI-SHOW-Canny（） - < edges> -onRefreshFLAG
cv2.imshow（DEMO.Canny ，edges）
pass
if（aCannyRefreshFLAG或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。上面in.onRefreshFLAG重新同步部分
＃------------------------------------- ------------------------------------------- GUI输入？ [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
如果__name__ =='__main__'：
main（）
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()
这篇关于opencv库中houghcircle函数中的dp参数究竟如何工作？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
查看全文
![http： //i.imgur.com/iGyr7TG.jpg](\"https://i.imgur.com/iGyr7TG.jpg\"){kind=link}
