day4 边缘检测Canny

1.canny边缘检测

# coding=utf-8
 
import cv2
import numpy as np
 
filename = 'woman.JPEG'
 
#读入图像，以灰度格式
img = cv2.imread(filename)
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
 
canny1 = cv2.Canny(img,200,300)
                  #200：最小阈值   300：最大阈值
                  #灰度梯度高于maxVal被认为是边界
                  #低于minVal抛弃
 
cv2.imshow("canny",canny1)
cv2.waitKey()
cv2.destroyAllWindows()

2.pyplot 应用

#-*- coding:utf-8 -*-
 
import cv2
import numpy as np
from matplotlib import pyplot as plt
 
filename = 'woman.JPEG'
 
img = cv2.imread(filename,0)
 
canny1 = cv2.Canny(img,200,300)
 
#plt.subplot(121),plt.imshow(img,cmap='woman')
plt.subplot(121),plt.imshow(img,cmap='gray')  #必须是gray
 
#1行2列 第2个图像
plt.subplot(122), plt.imshow(canny1,'gray')
plt.title('Edge Image')          #标题
plt.xticks([]), plt.yticks([])   #去除x y 轴
plt.xlim([0,500])               #图像y轴 0-500
 
plt.show()