Remove Images for which there are no annotations

[shanalikhan]

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Description

Hi,
Any idea how to remove the images where there are no annotations or we need to do it manually in JSON in COCO Format?

Use case

Cleaning COCO

Additional

N/a

Are you willing to submit a PR?

• Yes I'd like to help by submitting a PR!

[LinasKo]

Hi @shanalikhan,

I'm converting this to a discussion.

[shanalikhan]

I've written the manual code here:

coco_paths = [coco_output_train_folder,coco_output_test_folder]

### Removing the images with no annotations

for coco_path in coco_paths:
    coco_json = json.load(open(os.path.join(coco_path,'result.json')))
    print(f"Orignal Images Length : {len(coco_json['images'])}")
    missing_images = []
    for idx in tqdm(range(len(coco_json['images']))):
        img_id = coco_json['images'][idx]['id'] 
        img_annotations = list(filter(lambda x: x['image_id']==img_id,coco_json['annotations']))
        if len(img_annotations)==0:
            missing_images.append(idx)
    filtered_images = list(filter(lambda x: x['id'] not in missing_images,coco_json['images']))
    coco_json['images'] = filtered_images
    print(f"New Images Length : {len(filtered_images)}")
    json.dump(coco_json,open(os.path.join(coco_path,'result.json'),'w'))
            

[LinasKo]

Indeed, we do not have a quick way of doing it at the moment. I'd normally advise doing something similar to what you did.