閾値処理(threshold)

python 2.7
numpy 1.8.1
openCV 2.4.9
Windows 7 64bit

fig.1 gray

fig.2 cv2.THRESH_BINARY

fig.3 cv2.THRESH_BINARY_INV

fig.4 cv2.THRESH_OTSU

fig.5 cv2.THRESH_BINARY_INV+cv2.THRESH_OTSU

fig.6 cv2.THRESH_TOZERO_INV

fig.7 cv2.THRESH_TOZERO_INV, mask=cv2.THRESH_BINARY

threshold

import cv2.cv as cv import cv2 import numpy as np src = cv2.imread('lena.jpg') #fig.1 gray = cv2.cvtColor(src,cv2.COLOR_BGR2GRAY) cv2.imshow('gray',gray) cv2.imwrite('gray.png',gray) #fig.2 ret, thresh = cv2.threshold(gray, 100, 255, cv2.THRESH_BINARY) print ret cv2.imshow('binary',thresh) cv2.imwrite('thresh.png',thresh) #fig.3 ret_inv, thresh_inv = cv2.threshold(gray, 100, 255, cv2.THRESH_BINARY_INV) print ret_inv cv2.imshow('binary_inv',thresh_inv) cv2.imwrite('thresh_inv.png',thresh_inv) #fig.4 ret_otsu, thresh_otsu = cv2.threshold(gray, 0, 255, cv2.THRESH_OTSU) print ret_otsu cv2.imshow('binary_otsu',thresh_otsu) cv2.imwrite('thresh_otsu.png',thresh_otsu) #fig.5 ret_inv_otsu, thresh_inv_otsu = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY_INV+cv2.THRESH_OTSU) print ret_inv_otsu cv2.imshow('binary_inv_otsu',thresh_inv_otsu) cv2.imwrite('thresh_inv_otsu.png',thresh_inv_otsu) #fig.6 ret_tozero_inv, thresh_tozero_inv = cv2.threshold(gray, 100, 255, cv2.THRESH_TOZERO_INV) print ret_tozero_inv cv2.imshow('binary_tozero_inv',thresh_tozero_inv) cv2.imwrite('thresh_tozero_inv.png',thresh_tozero_inv) #fig.7 mask = thresh > 200 thresh_tozero_inv[mask] = 255 cv2.imshow('binary_tozero_inv_255',thresh_tozero_inv) cv2.imwrite('thresh_tozero_inv_255.png',thresh_tozero_inv) cv2.waitKey(0) cv2.destroyAllWindows()

LINK

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threshold