DHash Image Hashing algorithm with z-transformation

dhash_z_transformed.py

# Inspired from https://github.com/JohannesBuchner/imagehash repository
import imagehash
from PIL import Image

def alpharemover(image):
    if image.mode != 'RGBA':
        return image
    canvas = Image.new('RGBA', image.size, (255,255,255,255))
    canvas.paste(image, mask=image)
    return canvas.convert('RGB')

def with_ztransform_preprocess(hashfunc, hash_size=8):
    def function(path):
        image = alpharemover(Image.open(path))
        image = image.convert("L").resize((hash_size, hash_size), Image.ANTIALIAS)
        data = image.getdata()
        quantiles = np.arange(100)
        quantiles_values = np.percentile(data, quantiles)
        zdata = (np.interp(data, quantiles_values, quantiles) / 100 * 255).astype(np.uint8)
        image.putdata(zdata)
        return hashfunc(image)
    return function
  
dhash_z_transformed = with_ztransform_preprocess(imagehash.dhash, hash_size = 8)