Convert image to a matrix in python
Question:
I want to do some image processing using Python.
Is there a simple way to import .png image as a matrix of greyscale/RGB values (possibly using PIL)?
Answers:
im.load in PIL returns a matrix-like object.
you can use PyGame image and use PixelArray to access the pixeldata
scipy.misc.imread() will return a Numpy array, which is handy for lots of things.
Up till now no one told about matplotlib.image:
import matplotlib.image as img
image = img.imread(file_name)
Now the image would be a 3D numpy array
print image.shape
Would be something like: (317, 504, 3)
scipy.misc.imread() is deprecated now. We can use imageio.imread instead of that to read it as a Numpy array
Definitely try
from matplotlib.image import imread
image = imread(filename)
The filename preferably has to be an .jpg image.
And then, try
image.shape
This would return :
-
for a black and white or grayscale image
An (n,n) matrix where n represents the dimension of the images (pixels) and values inside the matrix range from 0 to 255.
Typically 0 is taken to be black, and 255 is taken to be white. 128 tends to be grey!
-
For color or RGB image
It will render a tensor of 3 channels. Each channel is an (n,n) matrix where each entry represents the respectively the level of Red, Green or Blue at the actual location inside the image.
I want to do some image processing using Python.
Is there a simple way to import .png image as a matrix of greyscale/RGB values (possibly using PIL)?
im.load in PIL returns a matrix-like object.
you can use PyGame image and use PixelArray to access the pixeldata
scipy.misc.imread() will return a Numpy array, which is handy for lots of things.
Up till now no one told about matplotlib.image:
import matplotlib.image as img
image = img.imread(file_name)
Now the image would be a 3D numpy array
print image.shape
Would be something like: (317, 504, 3)
scipy.misc.imread() is deprecated now. We can use imageio.imread instead of that to read it as a Numpy array
Definitely try
from matplotlib.image import imread
image = imread(filename)
The filename preferably has to be an .jpg image.
And then, try
image.shape
This would return :
-
for a black and white or grayscale image
An (n,n) matrix where n represents the dimension of the images (pixels) and values inside the matrix range from 0 to 255.
Typically 0 is taken to be black, and 255 is taken to be white. 128 tends to be grey! -
For color or RGB image
It will render a tensor of 3 channels. Each channel is an (n,n) matrix where each entry represents the respectively the level of Red, Green or Blue at the actual location inside the image.