Bulk/single image/s convert to Pink × Green duotone

green_duotone.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-
# @gist.github.com/motebaya - 3/9/2025
# rewrite from TS - https://lovable.dev/projects/8354edf5-ed78-4f83-8860-5ac9d2f067ff

import numpy as np
import os
from PIL import Image
import sys

OPTIMIZED_SHADOW = np.array([22, 80, 39], dtype=np.float32) #165027
OPTIMIZED_HIGHLIGHT = np.array([249, 159, 210], dtype=np.float32) #F99FD2
CLASSIC_SHADOW = np.array([27, 96, 47], dtype=np.float32) #1b602f
CLASSIC_HIGHLIGHT = np.array([247, 132, 197], dtype=np.float32) #f784c5

def duotone(
  imgp: str,
  classic: bool = False,
  reverse: bool = False,
  out: str = "",
) -> None:
  img = Image.open(imgp).convert("RGB")
  arr = np.asarray(img, dtype=np.float32)
  
  # using rec. 709 formula
  luminance = 0.2126 * arr[...,0] + 0.7152 * arr[...,1] + 0.0722 * arr[...,2]
  min_l, max_l = luminance.min(), luminance.max()
  norm = (luminance - min_l) / (max_l - min_l + 1e-6)
  
  # contrast
  norm = np.where(
    norm < 0.5, 
    np.power(norm * 2, 1.8) / 2,
    1 - np.power((1 - norm) * 2, 1.8) / 2
  )
  
  f = "duotone_"
  if classic:
    f += "classic"
    s, h = CLASSIC_SHADOW, CLASSIC_HIGHLIGHT
  else:
    s, h = OPTIMIZED_SHADOW, OPTIMIZED_HIGHLIGHT
    f += "optimized"
  
  if reverse:
    f += "_reverse"
    s, h = h, s
  
  f = f + "_" + os.path.basename(imgp)
  norm = norm[..., None]
  Image.fromarray(
    np.clip(
      s + norm * (h - s),
      0, 255
    ).astype(np.uint8),
    "RGB"
  ).save(os.path.join(out, f))
  print(f" * ok: {os.path.join(out, f)}")
  return

def fromdof(f: str, **kwargs) -> None:
  if os.path.isfile(f):
    duotone(f, **kwargs)
    return
  
  if os.path.isdir(f):
    out = os.path.join(f, "duotone_" + "reverse" if kwargs["reverse"] else "classic" if kwargs["classic"] else "original")
    os.makedirs(out, exist_ok=True)
    kwargs['out'] = out
    for x, file in enumerate(os.listdir(f), 1):
      print(f"{x:02d} | {file}")
      duotone(
        os.path.join(f, file),
        **kwargs,
      )
    return

if __name__ == "__main__":
  arg = sys.argv
  if len(arg) < 2:
    print("Usage: python pg_duotone.py <image_path> <mode>")
    sys.exit(1)

  mode = arg[2].split(",") if len(arg) > 2 else []
  assert all(
    m in (
      "classic",
      "reverse",
    ) for m in mode), "wrong mode!"
  fromdof(
    arg[1],
    reverse="reverse" in mode,
    classic="classic" in mode,
  )
  

Original	Classic	Reverse	Classic & Reverse