Question: Images without instance segmentation

[kimalaacer]

custom dataset with single class:
for images without annotations, should we give them an annotation id and leave all fields empty (see below) or just stop incrementing the annotation ids(skip image_id) if there is no annotation?:
{
"info": { },
"licenses": [{ }],
"categories": [{ }],
"images": [
{
"id": 1,
"file_name": "1.png","width": 640,"height": 640,"date_captured": "2020-11-23 20:27:52.616640","license": 1,"coco_url": "","flickr_url": ""},
{
"id": 30,"file_name": "9.png","width": 640,"height": 640,"date_captured": "2020-11-23 20:27:52.616640","license": 1,"coco_url": "",
"flickr_url": ""}],
"annotations": [{"id": 1,"image_id": 1,"category_id": 1,"iscrowd": 0,"area": 113,"bbox": [582.0,352.0,11.0,15.0],
"segmentation": [[ 592.0, ......]],"width": 640,"height": 640},
{
"id": 2,"image_id": 30,"category_id": ,"iscrowd": 0,"area": 0,"bbox": [ ],"segmentation": [[ ]],"width": 640,"height": 640},