third_party/mmyolo/tools/dataset_converters/labelme2coco.py

# Copyright (c) OpenMMLab. All rights reserved.
"""This script helps to convert labelme-style dataset to the coco format.

Usage:
    $ python labelme2coco.py \
                --img-dir /path/to/images \
                --labels-dir /path/to/labels \
                --out /path/to/coco_instances.json \
                [--class-id-txt /path/to/class_with_id.txt]

Note:
    Labels dir file structure:
    .
    └── PATH_TO_LABELS
         ├── image1.json
         ├── image2.json
         └── ...

    Images dir file structure:
    .
    └── PATH_TO_IMAGES
         ├── image1.jpg
         ├── image2.png
         └── ...

    If user set `--class-id-txt` then will use it in `categories` field,
    if not set, then will generate auto base on the all labelme label
    files to `class_with_id.json`.

    class_with_id.txt example, each line is "id class_name":
    ```text
    1 cat
    2 dog
    3 bicycle
    4 motorcycle

    ```
"""
import argparse
import json
from pathlib import Path
from typing import Optional

import numpy as np
from mmengine import track_iter_progress

from mmyolo.utils.misc import IMG_EXTENSIONS


def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument('--img-dir', type=str, help='Dataset image directory')
    parser.add_argument(
        '--labels-dir', type=str, help='Dataset labels directory')
    parser.add_argument('--out', type=str, help='COCO label json output path')
    parser.add_argument(
        '--class-id-txt', default=None, type=str, help='All class id txt path')
    args = parser.parse_args()
    return args


def format_coco_annotations(points: list, image_id: int, annotations_id: int,
                            category_id: int) -> dict:
    """Gen COCO annotations format label from labelme format label.

    Args:
        points (list): Coordinates of four vertices of rectangle bbox.
        image_id (int): Image id.
        annotations_id (int): Annotations id.
        category_id (int): Image dir path.

    Return:
        annotation_info (dict): COCO annotation data.
    """
    annotation_info = dict()
    annotation_info['iscrowd'] = 0
    annotation_info['category_id'] = category_id
    annotation_info['id'] = annotations_id
    annotation_info['image_id'] = image_id

    # bbox is [x1, y1, w, h]
    annotation_info['bbox'] = [
        points[0][0], points[0][1], points[1][0] - points[0][0],
        points[1][1] - points[0][1]
    ]

    annotation_info['area'] = annotation_info['bbox'][2] * annotation_info[
        'bbox'][3]  # bbox w * h
    segmentation_points = np.asarray(points).copy()
    segmentation_points[1, :] = np.asarray(points)[2, :]
    segmentation_points[2, :] = np.asarray(points)[1, :]
    annotation_info['segmentation'] = [list(segmentation_points.flatten())]

    return annotation_info


def parse_labelme_to_coco(
        image_dir: str,
        labels_root: str,
        all_classes_id: Optional[dict] = None) -> (dict, dict):
    """Gen COCO json format label from labelme format label.

    Args:
        image_dir (str): Image dir path.
        labels_root (str): Image label root path.
        all_classes_id (Optional[dict]): All class with id. Default None.

    Return:
        coco_json (dict): COCO json data.
        category_to_id (dict): category id and name.

    COCO json example:

    {
        "images": [
            {
                "height": 3000,
                "width": 4000,
                "id": 1,
                "file_name": "IMG_20210627_225110.jpg"
            },
            ...
        ],
        "categories": [
            {
                "id": 1,
                "name": "cat"
            },
            ...
        ],
        "annotations": [
            {
                "iscrowd": 0,
                "category_id": 1,
                "id": 1,
                "image_id": 1,
                "bbox": [
                    1183.7313232421875,
                    1230.0509033203125,
                    1270.9998779296875,
                    927.0848388671875
                ],
                "area": 1178324.7170306593,
                "segmentation": [
                    [
                        1183.7313232421875,
                        1230.0509033203125,
                        1183.7313232421875,
                        2157.1357421875,
                        2454.731201171875,
                        2157.1357421875,
                        2454.731201171875,
                        1230.0509033203125
                    ]
                ]
            },
            ...
        ]
    }
    """

    # init coco json field
    coco_json = {'images': [], 'categories': [], 'annotations': []}

    image_id = 0
    annotations_id = 0
    if all_classes_id is None:
        category_to_id = dict()
        categories_labels = []
    else:
        category_to_id = all_classes_id
        categories_labels = list(all_classes_id.keys())

        # add class_ids and class_names to the categories list in coco_json
        for class_name, class_id in category_to_id.items():
            coco_json['categories'].append({
                'id': class_id,
                'name': class_name
            })

    # filter incorrect image file
    img_file_list = [
        img_file for img_file in Path(image_dir).iterdir()
        if img_file.suffix.lower() in IMG_EXTENSIONS
    ]

    for img_file in track_iter_progress(img_file_list):

        # get label file according to the image file name
        label_path = Path(labels_root).joinpath(
            img_file.stem).with_suffix('.json')
        if not label_path.exists():
            print(f'Can not find label file: {label_path}, skip...')
            continue

        # load labelme label
        with open(label_path, encoding='utf-8') as f:
            labelme_data = json.load(f)

        image_id = image_id + 1  # coco id begin from 1

        # update coco 'images' field
        coco_json['images'].append({
            'height':
            labelme_data['imageHeight'],
            'width':
            labelme_data['imageWidth'],
            'id':
            image_id,
            'file_name':
            Path(labelme_data['imagePath']).name
        })

        for label_shapes in labelme_data['shapes']:

            # Update coco 'categories' field
            class_name = label_shapes['label']

            if (all_classes_id is None) and (class_name
                                             not in categories_labels):
                # only update when not been added before
                coco_json['categories'].append({
                    'id':
                    len(categories_labels) + 1,  # categories id start with 1
                    'name': class_name
                })
                categories_labels.append(class_name)
                category_to_id[class_name] = len(categories_labels)

            elif (all_classes_id is not None) and (class_name
                                                   not in categories_labels):
                # check class name
                raise ValueError(f'Got unexpected class name {class_name}, '
                                 'which is not in your `--class-id-txt`.')

            # get shape type and convert it to coco format
            shape_type = label_shapes['shape_type']
            if shape_type != 'rectangle':
                print(f'not support `{shape_type}` yet, skip...')
                continue

            annotations_id = annotations_id + 1
            # convert point from [xmin, ymin, xmax, ymax] to [x1, y1, w, h]
            (x1, y1), (x2, y2) = label_shapes['points']
            x1, x2 = sorted([x1, x2])  # xmin, xmax
            y1, y2 = sorted([y1, y2])  # ymin, ymax
            points = [[x1, y1], [x2, y2], [x1, y2], [x2, y1]]
            coco_annotations = format_coco_annotations(
                points, image_id, annotations_id, category_to_id[class_name])
            coco_json['annotations'].append(coco_annotations)

    print(f'Total image = {image_id}')
    print(f'Total annotations = {annotations_id}')
    print(f'Number of categories = {len(categories_labels)}, '
          f'which is {categories_labels}')

    return coco_json, category_to_id


def convert_labelme_to_coco(image_dir: str,
                            labels_dir: str,
                            out_path: str,
                            class_id_txt: Optional[str] = None):
    """Convert labelme format label to COCO json format label.

    Args:
        image_dir (str): Image dir path.
        labels_dir (str): Image label path.
        out_path (str): COCO json file save path.
        class_id_txt (Optional[str]): All class id txt file path.
            Default None.
    """
    assert Path(out_path).suffix == '.json'

    if class_id_txt is not None:
        assert Path(class_id_txt).suffix == '.txt'

        all_classes_id = dict()
        with open(class_id_txt, encoding='utf-8') as f:
            txt_lines = f.read().splitlines()
        assert len(txt_lines) > 0

        for txt_line in txt_lines:
            class_info = txt_line.split(' ')
            if len(class_info) != 2:
                raise ValueError('Error parse "class_id_txt" file '
                                 f'{class_id_txt},  please check if some of '
                                 'the class names is blank, like "1  " -> '
                                 '"1 blank", or class name has space between'
                                 ' words, like "1 Big house" -> "1 '
                                 'Big-house".')
            v, k = class_info
            all_classes_id.update({k: int(v)})
    else:
        all_classes_id = None

    # convert to coco json
    coco_json_data, category_to_id = parse_labelme_to_coco(
        image_dir, labels_dir, all_classes_id)

    # save json result
    Path(out_path).parent.mkdir(exist_ok=True, parents=True)
    print(f'Saving json to {out_path}')
    json.dump(coco_json_data, open(out_path, 'w'), indent=2)

    if class_id_txt is None:
        category_to_id_path = Path(out_path).with_name('class_with_id.txt')
        print(f'Saving class id txt to {category_to_id_path}')
        with open(category_to_id_path, 'w', encoding='utf-8') as f:
            for k, v in category_to_id.items():
                f.write(f'{v} {k}\n')
    else:
        print('Not Saving new class id txt, user should using '
              f'{class_id_txt} for training config')


def main():
    args = parse_args()
    convert_labelme_to_coco(args.img_dir, args.labels_dir, args.out,
                            args.class_id_txt)
    print('All done!')


if __name__ == '__main__':
    main()