Python OpenCV – imdecode()函数

Python cv2.imdecode()函数用于从内存缓存中读取图像数据并将其转换为图像格式。这通常用于从 Internet 有效地加载图像。

Syntax: cv2.imdecode(buf,flags)

Parameters:

• buf – It is the image data received  in bytes
• flags – It specifies the way in which image should be read. It’s default value is cv2.IMREAD_COLOR

Return: Image array

注意：如果给定的 buf 不是图像数据，则返回 NULL。

示例 1：

Python3

#import modules
import numpy as np
import urllib.request
import cv2
  
# read the image url
url = 'https://media.geeksforgeeks.org/wp-content/uploads/20211003151646/geeks14.png'
  
  
with urllib.request.urlopen(url) as resp:
    
    # read image as an numpy array
    image = np.asarray(bytearray(resp.read()), dtype="uint8")
      
    # use imdecode function
    image = cv2.imdecode(image, cv2.IMREAD_COLOR)
  
    # display image
    cv2.imwrite("result.jpg", image)

输出：

例 2：如果需要灰度，则可以使用 0 作为标志。

Python3

# import necessary modules
import numpy as np
import urllib.request
import cv2
  
# read image url
url = 'https://media.geeksforgeeks.org/wp-content/uploads/20211003151646/geeks14.png'
  
with urllib.request.urlopen(url) as resp:
  
    # convert to numpy array
    image = np.asarray(bytearray(resp.read()), dtype="uint8")
      
    # 0 is used for grayscale image
    image = cv2.imdecode(image, 0)
      
    # display image
    cv2.imwrite("result.jpg", image)

输出：

示例 3：从文件中读取图像

输入图像：

Python3

# import necessayr modules
import numpy as np
import urllib.request
import cv2
  
# read th image
with open("image.jpg", "rb") as image:
    
    f = image.read()
      
    # convert to numpy array
    image = np.asarray(bytearray(f))
      
    # RGB to Grayscale
    image = cv2.imdecode(image, 0)
      
    # display image
    cv2.imshow("output", image)

输出：