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利用trackbar找到理想的阈值（gray&HSV）

环境：python opencv ， jupyter notebook 有时候想要进行图片阈值处理，但是不能一下就找准想要的阈值。这时候，可以利用cv2.createTrackbar()函数。拖动bar改变阈值，观察图片的分割效果，当分割到理想效果时，看bar的值，即为最合适的阈值。gray和HSV都可以处理。效果图：

在这里插入图片描述 HSV空间分割浅绿色：

在这里插入图片描述 gray：

import cv2 import numpy as np def nothing(x): pass img = cv2.imread('Album.jpg',0) cv2.namedWindow("tracking") cv2.createTrackbar("l_T","tracking",220,255,nothing) # 220 起始值; 255 bar长度 cv2.createTrackbar("u_T","tracking",255,255,nothing) while True: l_T=cv2.getTrackbarPos("l_T","tracking") # lower threshold u_T=cv2.getTrackbarPos("u_T","tracking") # upper threshold _,mask = cv2.threshold(img,l_T,u_T,cv2.THRESH_BINARY_INV) # 阈值处理 cv2.imshow('img',img) cv2.imshow('mask',mask) key = cv2.waitKey(1) # Esc键 if key == 27: break cv2.destroyAllWindows()

HSV： createTrackbar中的startValue是绿色的HSV范围，随便设置也可，反正可调：

绿色的HSV： l_g = np.array([35, 43, 46]) # lower green value u_g = np.array([77,255,255]) # upper green

import cv2 import numpy as np def nothing(x): pass # use track bar to perfectly define (1/2) # the lower and upper values for HSV color space(2/2) cv2.namedWindow("Tracking") #参数：1 Lower/Upper HSV 3 startValue 4 endValue cv2.createTrackbar("LH","Tracking",35,255,nothing) cv2.createTrackbar("LS","Tracking",43,255,nothing) cv2.createTrackbar("LV","Tracking",46,255,nothing) cv2.createTrackbar("UH","Tracking",77,255,nothing) cv2.createTrackbar("US","Tracking",255,255,nothing) cv2.createTrackbar("UV","Tracking",255,255,nothing) while True: frame = cv2.imread('color.jpg') hsv = cv2.cvtColor(frame,cv2.COLOR_BGR2HSV) l_h = cv2.getTrackbarPos("LH","Tracking") l_s = cv2.getTrackbarPos("LS","Tracking") l_v = cv2.getTrackbarPos("LV","Tracking") u_h = cv2.getTrackbarPos("UH","Tracking") u_s = cv2.getTrackbarPos("US","Tracking") u_v = cv2.getTrackbarPos("UV","Tracking") l_g = np.array([l_h, l_s, l_v]) # lower green value u_g = np.array([u_h,u_s,u_v]) mask = cv2.inRange(hsv,l_g,u_g) res=cv2.bitwise_and(frame,frame,mask=mask) # src1,src2 cv2.imshow("frame", frame) cv2.imshow("mask", mask) cv2.imshow("res", res) key = cv2.waitKey(1) if key == 27: # Esc break cv2.destroyAllWindows()

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