Python中的 ImageIO 库入门

Imageio是一个Python库，它提供了一个简单的界面来读取和写入各种图像数据，包括动画图像、体积数据和科学格式。它是跨平台的。

安装：

这个模块没有内置在Python中。要安装它，请在终端中键入以下命令。

pip install imageio

要求：

• Python 3.5+
• 麻木的
• 枕头

要访问输入图像文件，请单击此处。让我们看看 imageio 库的一些工作代码：

1）读取图像：为了读取图像，我们必须使用imageio.imread()方法。

Syntax: imageio.imread(“filename or path”)

Parameter:

•  filename/path: Absolute or Relative path of the image file.

Return: returns a numpy array, which comes with a dict of meta data at its ‘meta’ attribute.

例子：

Python3

# import library
import imageio
  
# read an image
image = imageio.imread('testa.png')
  
# print shape of the image
print(image.shape)

输出：

(134, 151, 4)

2)读取 GIF 文件：为了读取GIF文件，我们必须使用imageio.get_reader()方法。

Syntax: imageio.get_reader(filename, format, mode)

Parameters:

• path/filename: FileName of required image/file/gif .
• format: str, The format to used to read the file, By default imageio select the appropriate for you ,based on the filename and its contents.
•  mode: {‘i’, ‘I’, ‘v’, ‘V’, ‘?’}
  • Used to give the reader a hint on what the user expects (default “?”):
  • ‘i’ for an image
  • I’ for multiple images
  • ‘v’ for a volume
  • ‘V’ for multiple volumes
  • ?’ for don’t care    

Returns: Reader`object which can be used to read data and meta-data from the specified file.

例子：

Python3

# import library
import imageio
  
# create an image object
image = imageio.get_reader('test.gif')
  
# iterating through matrix:
for i in image :
    
  # Each frame is a numpy matrix
  print(i.shape)

输出：

(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)
(300, 354, 4)

3）创建图像文件：为了创建图像文件，我们必须使用imageio.imwrite()方法。

Syntax: imageio.imwrite(filename,numPy_ndarray, format=None) 

Parameters:

• filename: Path / Name of file to be saved as
• numpy_ndarray: The image data. Must be NxM, NxMx3 or NxMx4.
• format: str, The format to used to read the file. By default, imageio selects, the appropriate for you, based on the filename and its contents.

例子：

Python3

# import required libraries
import imageio
import numpy as np
  
  
rows, cols = (5, 5) 
  
# create numpy 2-d array
arr = np.zeros((rows, cols))
  
# create an image
image = imageio.imwrite('image_writing.png', 
                     arr)

输出：

image_writing.png.png

由于数据值为零，因此这是 68 字节大小的空图像。