Python OpenCV | cv2.copyMakeBorder() 方法

OpenCV-Python是一个Python绑定库，旨在解决计算机视觉问题。 cv2.copyMakeBorder() 方法用于在图像周围创建边框，如相框。

Syntax: cv2.copyMakeBorder(src, top, bottom, left, right, borderType, value)

Parameters: 
src: It is the source image. 
top: It is the border width in number of pixels in top direction. 
bottom: It is the border width in number of pixels in bottom direction. 
left: It is the border width in number of pixels in left direction. 
right: It is the border width in number of pixels in right direction. 
borderType: It depicts what kind of border to be added. It is defined by flags like cv2.BORDER_CONSTANT, cv2.BORDER_REFLECT, etc dest: It is the destination image
value: It is an optional parameter which depicts color of border if border type is cv2.BORDER_CONSTANT.

Return Value: It returns an image. 
 

边界类型标志描述如下：

cv2.BORDER_CONSTANT: It adds a constant colored border. The value should be given as a keyword argument
cv2.BORDER_REFLECT: The border will be mirror reflection of the border elements. Suppose, if image contains letters “abcdefg” then output will be “gfedcba|abcdefg|gfedcba“. 
cv2.BORDER_REFLECT_101 or cv2.BORDER_DEFAULT: It does the same works as cv2.BORDER_REFLECT but with slight change. Suppose, if image contains letters “abcdefgh” then output will be “gfedcb|abcdefgh|gfedcba“. 
cv2.BORDER_REPLICATE: It replicates the last element. Suppose, if image contains letters “abcdefgh” then output will be “aaaaa|abcdefgh|hhhhh“. 
 

用于以下所有示例的图像：

示例 #1：

Python3

# Python program to explain cv2.copyMakeBorder() 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'
 
# Using cv2.copyMakeBorder() method
image = cv2.copyMakeBorder(image, 10, 10, 10, 10, cv2.BORDER_CONSTANT, None, value = 0)
 
# Displaying the image
cv2.imshow(window_name, image)

输出：

示例 #2：

Python3

# Python program to explain cv2.copyMakeBorder() 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'
 
# Using cv2.copyMakeBorder() method
image = cv2.copyMakeBorder(image, 100, 100, 50, 50, cv2.BORDER_REFLECT)
 
# Displaying the image
cv2.imshow(window_name, image)

输出：