convert_coco2017_captions.py

import json
import os
import argparse
from tqdm import tqdm

def parse_args():
    parser = argparse.ArgumentParser(
        description="Convert COCO2017 captions to LLaMA-Factory jsonl format"
    )
    parser.add_argument(
        "--coco-root",
        type=str,
        required=True,
        help="COCO2017 root directory (default: /workspace/DL_DATA/COCO2017/)"
    )
    parser.add_argument(
        "--output",
        type=str,
        default="./data/coco_train2017_captions.jsonl",
        help="Output jsonl file path"
    )
    parser.add_argument(
        "--prompt",
        type=str,
        default="<image>\nDescribe the image.",
        help="Human prompt text"
    )
    return parser.parse_args()
    
def main():
    args = parse_args()
    coco_root = args.coco_root
    output_jsonl = args.output
    human_prompt = args.prompt

    caption_json = os.path.join(coco_root, "annotations_new/captions_train2017.json")
    image_dir = os.path.join(coco_root, "images/train2017")

    assert os.path.exists(caption_json), f"Caption file not found: {caption_json}"
    assert os.path.exists(image_dir), f"Image dir not found: {image_dir}"

    with open(caption_json, "r", encoding="utf-8") as f:
        coco = json.load(f)

    # image_id -> file_name
    id2file = {img["id"]: img["file_name"] for img in coco["images"]}
    annotations = coco["annotations"]
    os.makedirs(os.path.dirname(output_jsonl), exist_ok=True)

    with open(output_jsonl, "w", encoding="utf-8") as out_f:
        for ann in tqdm(annotations, desc="Converting COCO captions"):
            image_id = ann["image_id"]
            caption = ann["caption"].strip()
            file_name = id2file[image_id]

            image_path = os.path.join(image_dir, file_name)

            sample = {
                "image": image_path,
                "conversations": [
                    {
                        "from": "human",
                        "value": human_prompt
                    },
                    {
                        "from": "gpt",
                        "value": caption
                    }
                ]
            }

            out_f.write(json.dumps(sample, ensure_ascii=False) + "\n")
    print(f"Done. Saved to {output_jsonl}")

if __name__ == "__main__":
    main()