47 lines
1.7 KiB
Python
47 lines
1.7 KiB
Python
|
#!/usr/bin/env python3
|
||
|
|
"""Composite a native-transparent keyframe onto a uniform video chroma backdrop."""
|
||
|
|
|
||
|
|
from __future__ import annotations
|
||
|
|
|
||
|
|
import argparse
|
||
|
|
import re
|
||
|
|
from pathlib import Path
|
||
|
|
|
||
|
|
from PIL import Image
|
||
|
|
|
||
|
|
|
||
|
|
def parse_color(value: str) -> tuple[int, int, int, int]:
|
||
|
|
if not re.fullmatch(r"#[0-9a-fA-F]{6}", value):
|
||
|
|
raise SystemExit(f"invalid key color: {value}; expected #RRGGBB")
|
||
|
|
return tuple(int(value[index : index + 2], 16) for index in (1, 3, 5)) + (255,)
|
||
|
|
|
||
|
|
|
||
|
|
def main() -> None:
|
||
|
|
parser = argparse.ArgumentParser(description=__doc__)
|
||
|
|
parser.add_argument("source", help="Accepted native-transparent keyframe PNG")
|
||
|
|
parser.add_argument("output", help="RGB PNG for the video model")
|
||
|
|
parser.add_argument("--key-color", default="#00FF00")
|
||
|
|
args = parser.parse_args()
|
||
|
|
|
||
|
|
source = Path(args.source).expanduser().resolve()
|
||
|
|
output = Path(args.output).expanduser().resolve()
|
||
|
|
if source == output:
|
||
|
|
raise SystemExit("source and output must differ; preserve the native-transparent keyframe")
|
||
|
|
|
||
|
|
with Image.open(source) as opened:
|
||
|
|
if "A" not in opened.getbands():
|
||
|
|
raise SystemExit("source has no alpha channel; regenerate it with native transparency")
|
||
|
|
foreground = opened.convert("RGBA")
|
||
|
|
alpha_min, alpha_max = foreground.getchannel("A").getextrema()
|
||
|
|
if alpha_min > 16 or alpha_max <= 16:
|
||
|
|
raise SystemExit("source must contain both transparent background and visible subject pixels")
|
||
|
|
|
||
|
|
background = Image.new("RGBA", foreground.size, parse_color(args.key_color))
|
||
|
|
background.alpha_composite(foreground)
|
||
|
|
output.parent.mkdir(parents=True, exist_ok=True)
|
||
|
|
background.convert("RGB").save(output)
|
||
|
|
print(output)
|
||
|
|
|
||
|
|
|
||
|
|
if __name__ == "__main__":
|
||
|
|
main()
|