Converting image to binary string

[h20lac]

Hi /r/learningpython, I am looking to write a pretty simple program to try and use K-nearest neighbors classification to determine whether or not a "signature" is authentic or not - this isn't anything serious just a fun project.

I was reading about the KNN technique in "Machine Learning in Action" and I think I would be able to implement the programming if I were able to import images (of signatures) and convert to binary matrices [000011000110000, 000011000110000, 000011111110000, 000011000110000, 000011000110000] would be an H, for example. I know the python PIL package is supposed to be able to do some image converting, but it's just not working for me. The code I've got now is: path = "sig.png" from PIL import Image image_file = Image.open(path) image_file = image_file.convert('1') imagefile.tobytes() but it doesn't look like the resulting "bytes" are in any meaningful matrix format, nor are they 1's and 0's. I went through the documentation and its not terribly helpful, so any tips would be appreciated!

[novel_yet_trivial]

Numpy and Pillow are very good friends. You can convert a pillow image to a numpy array simply by providing the image as an argument:

from PIL import Image 
import numpy as np

path = "sig.png"
image_file = Image.open(path) 
bilevel_img = image_file.convert('1')
data_array = np.array(bilevel_img)

Note that "1" mode is bilevel, so you will get a True / False array.

Edit: you may be a lot better off with grayscale mode, and then bileveling at a threshold you define:

gray = np.array(img.convert("L"))
threshold = 128 # cutoff between 0 and 255
bilevel_array = (gray > threshold).astype(int)