Python [plt 和 cv] 图片读取、显示和保存_pltcv

1. 图片读取方式

读取图片，并设置图片大小

1. keras 导入

   img = load_img(image_path, target_size=target_input) # 设置导入尺寸
   
   plt.imshow(img)
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2. opencv 导入

   img = cv2.imread(image_path)
   img = cv2.resize(img, target_input[:2])   # cv.resize 值只接受（h, w）
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2. 绘图

2.1 图片显示

1. opencv 绘制 （默认 gbr）

   cv2.imshow(windown, img)  # window 可以随意命名
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   若不能正常显示：

   cv2.waitKey(0)  # 键盘绑定函数，等待按键
   cv2.destroyAllWindows() # 按下键盘中的按键，启动该程序销毁所有窗口
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2. plt 显示

   使用 img = cv2.cvtColor(img,cv2.COLOR_BGR2RGB) 可以先将opencv读取的bgr转化为plt可以读取的bgr格式

   plt.imshow()
   plt.show()
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2.2 关闭坐标显示

plt.xticks([]) # 关闭x坐标显示
plt.yticks([]) # 关闭y坐标显示
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3. 保存图片

保存在当前目录下（或者使用绝对地址）

plt.savefig('./result.jpg')
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4. 实例

• 矩阵边线

# Python program to explain cv2.rectangle() method 

# importing cv2 
import cv2 

# path 
path = r'C:\Users\Rajnish\Desktop\geeksforgeeks\geeks.png'

# Reading an image in default mode 
image = cv2.imread(path) 

# Window name in which image is displayed 
window_name = 'Image'

# Start coordinate, here (5, 5) 
# represents the top left corner of rectangle 
start_point = (5, 5) 

# Ending coordinate, here (220, 220) 
# represents the bottom right corner of rectangle 
end_point = (220, 220) 

# Blue color in BGR 
color = (255, 0, 0) 

# Line thickness of 2 px 
thickness = 2

# Using cv2.rectangle() method 
# Draw a rectangle with blue line borders of thickness of 2 px 
image = cv2.rectangle(image, start_point, end_point, color, thickness) 

# Displaying the image 
cv2.imshow(window_name, image) 

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• 实心矩阵

# Python program to explain cv2.rectangle() method 
	
# importing cv2 
import cv2 
	
# path 
path = r'C:\Users\Rajnish\Desktop\geeksforgeeks\geeks.png'
	
# Reading an image in grayscale mode 
image = cv2.imread(path, 0) 
	
# Window name in which image is displayed 
window_name = 'Image'

# Start coordinate, here (100, 50) 
# represents the top left corner of rectangle 
start_point = (100, 50) 

# Ending coordinate, here (125, 80) 
# represents the bottom right corner of rectangle 
end_point = (125, 80) 

# Black color in BGR 
color = (0, 0, 0) 

# Line thickness of -1 px 
# Thickness of -1 will fill the entire shape 
thickness = -1

# Using cv2.rectangle() method 
# Draw a rectangle of black color of thickness -1 px 
image = cv2.rectangle(image, start_point, end_point, color, thickness) 

# Displaying the image 
cv2.imshow(window_name, image) 

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参考