deluge-recolor.py

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


def recolor_blue_to_red(image_path):
    img = Image.open(image_path)

    # Preserve original format
    original_format = img.format

    print(image_path, img.mode)

    # Handle alpha channel if present
    if img.mode in ("RGBA", "LA", "P"):
        img = img.convert("RGBA")
        alpha = img.getchannel("A")
        img = img.convert("RGB")
        has_alpha = True
    else:
        img = img.convert("RGB")
        has_alpha = False

    # Convert to HSV
    hsv = img.convert("HSV")
    hsv_np = np.array(hsv)

    h = hsv_np[:, :, 0]

    # Blue hue range in Pillow HSV (0–255 scale)
    blue_min = 140
    blue_max = 200

    # Mask blue pixels
    mask = (h >= blue_min) & (h <= blue_max)

    # Shift blue hue to red (red ≈ 0)
    h[mask] = 0

    hsv_np[:, :, 0] = h
    recolored = Image.fromarray(hsv_np, "HSV").convert("RGB")

    # Reattach alpha if needed
    if has_alpha:
        recolored.putalpha(alpha)

    # Save to same path, same format
    recolored.save(image_path, format=original_format)


if __name__ == "__main__":
    if len(sys.argv) != 2:
        print(f"Usage: python {sys.argv[0]} <image_path>")
        sys.exit(1)

    image_path = sys.argv[1]

    if not os.path.isfile(image_path):
        print("Error: File not found.")
        sys.exit(1)

    recolor_blue_to_red(image_path)
    print("Image recolored successfully.")

deluge.nix

{ pkgs, ... }:
let
  recolor = pkgs.writers.writePython3 "recolor" {
    libraries = [pkgs.python3Packages.pillow pkgs.python3Packages.numpy];
  } (builtins.readFile ./deluge-recolor.py);
  in 
{
  config.services.deluge = {
    enable = true;
    declarative = true;
    package = pkgs.deluge-2_x.overrideAttrs ({postInstall ? "", ...}: {
      postInstall = postInstall + ''
        for file in $out/${pkgs.python3Packages.python.sitePackages}/deluge/ui/web/icons/deluge-*.png; do
          ${recolor} $file
        done
      '';
    });
   # ...
}