opencv图像处理(一)图像的基本操作
图像的基本操作包括图像的数据读取(图像的大小)、图像的显示、图像的保存、读取视频、图像的截屏、颜色通道信息提取、边界填充、数值计算和图像的融合。
图像的数据读取
import cv2 ***
import matplotlib.pyplot as plt
import numpy as np
img=cv2.imread('F:/deeplearning/opencv/2_7/image operate/cat.jpg')
print(img.shape)
print(img)
图像的显示
cv2.imshow('image',img)
cv2.waitKey(0)
cv2.destroyAllWindows()
图像显示函数
def cv_show(name,img):
cv2.imshow(name,img)
cv2.waitKey(0)
cv2.destroyAllWindows()
```python
cv2.IMREAD_COLOR:彩色图像 cv2.IMREAD_GRAYSCALE:灰度图像(此时只有一个通道) 图片灰度图像读取
```python
img=cv2.imread('cat.jpg',cv2.IMREAD_GRAYSCALE)
print(img)
print(img,shape)
图像的保存
cv2.imwrite('mycat.png',img)
读取视频
- cv2.VideoCapture可以捕获摄像头,用数字来控制不同的设备,例如0,1。
- 如果是视频文件,直接指定好路径即可。
vc = cv2.VideoCapture('test.mp4')
if vc.isOpened():
oepn, frame = vc.read()
else:
open = False
while open:
ret, frame = vc.read()
if frame is None:
break
if ret == True:
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.imshow('result', gray)
if cv2.waitKey(100) & 0xFF == 27:
break
vc.release()
cv2.destroyAllWindows()
图像截屏
img=cv2.imread('cat.jpg')
cat=img[0:50,0:200]
cv_show('cat',cat)
颜色通道提取
b,g,r=cv2.split(img)
r
r.shape
img=cv2.merge((b,g,r))
img.shape
cur_img = img.copy()
cur_img[:,:,0] = 0
cur_img[:,:,1] = 0
cv_show('R',cur_img)
cur_img = img.copy()
cur_img[:,:,0] = 0
cur_img[:,:,2] = 0
cv_show('G',cur_img)
cur_img = img.copy()
cur_img[:,:,1] = 0
cur_img[:,:,2] = 0
cv_show('B',cur_img)
#%% md
边界填充
- BORDER_REPLICATE:复制法,也就是复制最边缘像素。
- BORDER_REFLECT:反射法,对感兴趣的图像中的像素在两边进行复制例如:fedcba|abcdefgh|hgfedcb
- BORDER_REFLECT_101:反射法,也就是以最边缘像素为轴,对称,gfedcb|abcdefgh|gfedcba
- BORDER_WRAP:外包装法cdefgh|abcdefgh|abcdefg
- BORDER_CONSTANT:常量法,常数值填充。
top_size,bottom_size,left_size,right_size = (50,50,50,50)
replicate = cv2.copyMakeBorder(img, top_size, bottom_size, left_size, right_size, borderType=cv2.BORDER_REPLICATE)
reflect = cv2.copyMakeBorder(img, top_size, bottom_size, left_size, right_size,cv2.BORDER_REFLECT)
reflect101 = cv2.copyMakeBorder(img, top_size, bottom_size, left_size, right_size, cv2.BORDER_REFLECT_101)
wrap = cv2.copyMakeBorder(img, top_size, bottom_size, left_size, right_size, cv2.BORDER_WRAP)
constant = cv2.copyMakeBorder(img, top_size, bottom_size, left_size, right_size,cv2.BORDER_CONSTANT, value=0)
import matplotlib.pyplot as plt
plt.subplot(231), plt.imshow(img, 'gray'), plt.title('ORIGINAL')
plt.subplot(232), plt.imshow(replicate, 'gray'), plt.title('REPLICATE')
plt.subplot(233), plt.imshow(reflect, 'gray'), plt.title('REFLECT')
plt.subplot(234), plt.imshow(reflect101, 'gray'), plt.title('REFLECT_101')
plt.subplot(235), plt.imshow(wrap, 'gray'), plt.title('WRAP')
plt.subplot(236), plt.imshow(constant, 'gray'), plt.title('CONSTANT')
plt.show()
数值计算
img_cat=cv2.imread('cat.jpg')
img_dog=cv2.imread('dog.jpg')
img_cat2= img_cat +10
img_cat[:5,:,0]
img_cat2[:5,:,0]
(img_cat + img_cat2)[:5,:,0]
cv2.add(img_cat,img_cat2)[:5,:,0]
图像融合
img_cat + img_dog
img_cat.shape
img_dog = cv2.resize(img_dog, (500, 414))
img_dog.shape
res = cv2.addWeighted(img_cat, 0.4, img_dog, 0.6, 0)
plt.imshow(res)
res = cv2.resize(img, (0, 0), fx=4, fy=4)
plt.imshow(res)
res = cv2.resize(img, (0, 0), fx=1, fy=3)
plt.imshow(res)
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