scripts/data_collection/caption_opus.py

"""
Caption images using Anthropic Claude Opus 4.6 API.
Generates detailed descriptions for fine-tuning Flux.
"""
import os
import json
import base64
import argparse
import time
from pathlib import Path
from concurrent.futures import ThreadPoolExecutor, as_completed

import anthropic
from tqdm import tqdm

INPUT_DIR = Path("/home/adminuser/chungcat/data/raw/unsplash")
OUTPUT_DIR = Path("/home/adminuser/chungcat/data/captions")

CAPTION_PROMPT = """Describe this image in detail for an AI image generation model. Include:
- Main subject and composition
- Colors, lighting, mood
- Style (photographic, artistic, etc.)
- Important details and textures
- Background elements

Write a single detailed paragraph, 2-4 sentences. Be specific and descriptive."""


def encode_image(image_path):
    with open(image_path, "rb") as f:
        return base64.standard_b64encode(f.read()).decode("utf-8")


def caption_image(client, image_path, model="claude-opus-4-6-20250219"):
    img_data = encode_image(image_path)
    suffix = image_path.suffix.lower()
    media_type = "image/jpeg" if suffix in [".jpg", ".jpeg"] else "image/png"

    response = client.messages.create(
        model=model,
        max_tokens=300,
        messages=[
            {
                "role": "user",
                "content": [
                    {
                        "type": "image",
                        "source": {
                            "type": "base64",
                            "media_type": media_type,
                            "data": img_data,
                        },
                    },
                    {"type": "text", "text": CAPTION_PROMPT},
                ],
            }
        ],
    )
    return response.content[0].text


def process_batch(client, images, output_dir, model, max_retries=3):
    results = []
    for img_path in images:
        output_path = output_dir / f"{img_path.stem}.json"
        if output_path.exists():
            continue

        for attempt in range(max_retries):
            try:
                caption = caption_image(client, img_path, model)
                result = {
                    "image": str(img_path),
                    "caption": caption,
                    "filename": img_path.name,
                }
                output_path.write_text(json.dumps(result, ensure_ascii=False))
                results.append(result)
                break
            except anthropic.RateLimitError:
                time.sleep(2 ** attempt)
            except Exception as e:
                print(f"Error {img_path.name}: {e}")
                if attempt == max_retries - 1:
                    print(f"  Skipping after {max_retries} retries")
                time.sleep(1)

    return results


def main():
    parser = argparse.ArgumentParser(description="Caption images with Claude Opus")
    parser.add_argument("--input-dir", type=Path, default=INPUT_DIR)
    parser.add_argument("--output-dir", type=Path, default=OUTPUT_DIR)
    parser.add_argument("--model", default="claude-opus-4-6-20250219")
    parser.add_argument("--batch-size", type=int, default=10)
    parser.add_argument("--workers", type=int, default=5)
    parser.add_argument("--max-images", type=int, default=None)
    args = parser.parse_args()

    api_key = os.environ.get("ANTHROPIC_API_KEY")
    if not api_key:
        raise ValueError("Set ANTHROPIC_API_KEY environment variable")

    client = anthropic.Anthropic(api_key=api_key)
    args.output_dir.mkdir(parents=True, exist_ok=True)

    images = sorted(args.input_dir.glob("*.jpg")) + sorted(args.input_dir.glob("*.png"))
    if args.max_images:
        images = images[:args.max_images]

    already_done = len(list(args.output_dir.glob("*.json")))
    images = [img for img in images if not (args.output_dir / f"{img.stem}.json").exists()]

    print(f"Total images: {len(images) + already_done}")
    print(f"Already captioned: {already_done}")
    print(f"To caption: {len(images)}")

    batches = [images[i:i+args.batch_size] for i in range(0, len(images), args.batch_size)]

    total_captioned = 0
    with ThreadPoolExecutor(max_workers=args.workers) as executor:
        futures = [
            executor.submit(process_batch, client, batch, args.output_dir, args.model)
            for batch in batches
        ]
        for future in tqdm(as_completed(futures), total=len(futures)):
            results = future.result()
            total_captioned += len(results)

    print(f"\nDone! Captioned {total_captioned} new images")
    print(f"Total captions: {already_done + total_captioned}")


if __name__ == "__main__":
    main()