pythonのメモ: 7月 2014

2014/07/30

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