如何在Python中打开图像

Question

I am new to Stackoverflow and still learning python but I am attempting to begin a project of mine. I plan on creating a filter for images using python. The first step I would like to learn is how to open up an image in python. This is what I have so far:

from PIL import Image
im = Image.open('Jordan.jpg')
im.show()

Am I on the right track? Iam using Python 2.7

Answer 1

the most natural python object that corresponds to an image is a multi-dimensional array; that's the most natural representation and it's also the best data structure to manipulate an image, as you intend to do by creating a filter.

Python has an array module, however, for creating and manipulating multi-dimensional arrays (eg, creating a filter), i highly recommend installing two python libraries NumPy and SciPy either from the links supplied here or pip installing them:

pip install numpy
pip install scipy


>>> from scipy import misc as MSC
>>> imfile = "~/path/to/an/image.jpg"

use the imread function in scipy's miscellaneous module, which in fact just calls PIL under the hood; this function will read in jpeg as well as png images

>>> img = MSC.imread(imfile)

verify that it is a NumPy array

>>> isinstance(img, NP.ndarray)
True 

a color image has three axes: X (width) Y (height), and Z (the three elements that comprise an RGB tuple;

first two axes are the pixel width and height of the image, the last dimension should be '3' (or '4' for an 'png' image which has an alpha channel)

>>> img.shape
(200, 200, 3)

selecting one pixel roughly from the image center (a single RGB 3-tuple)

>>> img[100,100,:]
array([83, 26, 17], dtype=uint8)

if you call Matplotlib's imshow method and pass in this NumPy array, it will render the image