CODEWITHSUNDEEP
pythondata-sciencepgm
victor2605
victor2605

Reputation: 33

How to read PGM P2 image in Python

So first, I'm in a mission on AI's college group. I have a dataset with many faces in PGM P2(ASCII) format. Before starting Neural Network proccess, I need to extract the array of pixels from images, but I can't found a way to read these images in Python.

I've already tried PIL but it doesn't work with PGM P2.

Can I do this in Python? Any help would be much appreciated.

Upvotes: 3

Views: 3597

Answers (1)

Felix
Felix

Reputation: 196

I know it's a little late to answer but I ran into the same issue and I thought it might be useful to post my solution. There does not seem to exist a library that reads ASCII based PGM (P2) on Python.

Here is my function, it takes in the name of the file and returns a tuple with: (1) A 1xn numpy array with the data, (2) A tuple containing the length and width, (3) The number of shades of gray.

import numpy as np
import matplotlib.pyplot as plt

def readpgm(name):
    with open(name) as f:
        lines = f.readlines()

    # Ignores commented lines
    for l in list(lines):
        if l[0] == '#':
            lines.remove(l)

    # Makes sure it is ASCII format (P2)
    assert lines[0].strip() == 'P2' 

    # Converts data to a list of integers
    data = []
    for line in lines[1:]:
        data.extend([int(c) for c in line.split()])

    return (np.array(data[3:]),(data[1],data[0]),data[2])

data = readpgm('/location/of/file.pgm')

plt.imshow(np.reshape(data[0],data[1])) # Usage example

Upvotes: 3

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