Python Image hashing

Question

I'm currently trying to get a hash from an image in python, i have successfully done this and it works somewhat.

However, I have this issue: Image1 and image2 end up having the same hash, even though they are different. I need a form of hashing which is more accurate and precise.

Image1 = Image1

Image2 = Image2

The hash for the images is: faf0761493939381

I am currently using from PIL import Image import imagehash

And imagehash.average_hash

Code here

import os
from PIL import Image
import imagehash


def checkImage():
    for filename in os.listdir('images//'):
        hashedImage = imagehash.average_hash(Image.open('images//' + filename))
    print(filename, hashedImage)

    for filename in os.listdir('checkimage//'):
        check_image = imagehash.average_hash(Image.open('checkimage//' + filename))
    print(filename, check_image)

    if check_image == hashedImage:
        print("Same image")
    else:
        print("Not the same image")

    print(hashedImage, check_image)


checkImage()

Answer 1

Try using hashlib. Just open the file and perform a hash.

import hashlib

# Simple solution
with open("image.extension", "rb") as f:
    hash = hashlib.sha256(f.read()).hexdigest()

# General-purpose solution that can process large files
def file_hash(file_path):
    # https://stackoverflow.com/questions/22058048/hashing-a-file-in-python

    sha256 = hashlib.sha256()

    with open(file_path, "rb") as f:
        while True:
            data = f.read(65536) # arbitrary number to reduce RAM usage
            if not data:
                break
            sha256.update(data)

    return sha256.hexdigest()

Thanks to Antonín Hoskovec for pointing out that it should be read binary (rb), not simple read (r)!

Answer 2

By default, imagehash checks if image files are nearly identical. The files you are comparing are more similar than they are not. If you want a more or less unique way of fingerprinting files you can use a different approach, such as employing a cryptographic hashing algorithm:

import hashlib

def get_hash(img_path):
    # This function will return the `md5` checksum for any input image.
    with open(img_path, "rb") as f:
        img_hash = hashlib.md5()
        while chunk := f.read(8192):
           img_hash.update(chunk)
    return img_hash.hexdigest()