#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# don't forget: pip install Pillow

import math
from PIL import Image

source = Image.open("image.tif")

def ycc(r, g, b):
    y = .299*r + .587*g + .114*b
    cb = 128 -.168736*r -.331364*g + .5*b
    cr = 128 +.5*r - .418688*g - .081312*b
    return y, cb, cr

def rgb(y, cb, cr):
    r = y + 1.402 * (cr-128)
    g = y - .34414 * (cb-128) -  .71414 * (cr-128)
    b = y + 1.772 * (cb-128)
    return round(r), round(g), round(b)

data = []
min_luma = 255
max_luma = 0
for pixel in source.getdata():
    yuv_pixel = ycc(*pixel)
    luma = yuv_pixel[0]
    log_luma = math.log(yuv_pixel[0],10)
    min_luma = min(min_luma, log_luma)
    max_luma = max(max_luma, log_luma)
    data.append((log_luma, yuv_pixel[1], yuv_pixel[2]))

luma_range = max_luma - min_luma
luma_factor = luma_range / 192

for index,pixel in enumerate(data):
    pixel = (round((pixel[0] - min_luma) / luma_factor), pixel[1], pixel[2])
    rgb_pixel = rgb(*pixel)
    data[index] = rgb_pixel

print(min_luma)
print(max_luma)

enhanced = Image.new('RGB', source.size)
enhanced.putdata(data)
enhanced.save('enhanced.tif')