SizeMismatchError When trying to train a model using a custom dataset

[vylly]

I'm trying to train a model using a custom dataset (I made sure to have a COCO style json file for my dataset) but when I'm trying to train a model using it I receive a SizeMismatchError.

Here is the code for what I'm doing :

cfg = get_cfg()

cfg.merge_from_file("../detectron2/configs/COCO-InstanceSegmentation/mask_rcnn_R_50_FPN_3x.yaml")
cfg.DATASETS.TRAIN = ("flowchart",)
cfg.DATASETS.TEST = ()   
cfg.DATALOADER.NUM_WORKERS = 2
cfg.MODEL.WEIGHTS = "detectron2://COCO-InstanceSegmentation/mask_rcnn_R_50_FPN_3x/137849600/model_final_f10217.pkl"  # initialize from model zoo
cfg.SOLVER.IMS_PER_BATCH = 1
cfg.SOLVER.BASE_LR = 0.00025
cfg.SOLVER.MAX_ITER = 300   
cfg.MODEL.ROI_HEADS.BATCH_SIZE_PER_IMAGE = 128  
cfg.MODEL.ROI_HEADS.NUM_CLASSES = 7 # my dataset has 7 classes

os.makedirs(cfg.OUTPUT_DIR, exist_ok=True)
trainer = DefaultTrainer(cfg) 
trainer.resume_or_load(resume=False)
trainer.train()

And here is the log :

SizeMismatchError: Caught SizeMismatchError in DataLoader worker process 0.
Original Traceback (most recent call last):
  File "/home/william/.conda/envs/detectron2-env/lib/python3.6/site-packages/torch/utils/data/_utils/worker.py", line 178, in _worker_loop
    data = fetcher.fetch(index)
  File "/home/william/.conda/envs/detectron2-env/lib/python3.6/site-packages/torch/utils/data/_utils/fetch.py", line 44, in fetch
    data = [self.dataset[idx] for idx in possibly_batched_index]
  File "/home/william/.conda/envs/detectron2-env/lib/python3.6/site-packages/torch/utils/data/_utils/fetch.py", line 44, in <listcomp>
    data = [self.dataset[idx] for idx in possibly_batched_index]
  File "/home/william/detectron2/detectron2/data/common.py", line 39, in __getitem__
    data = self._map_func(self._dataset[cur_idx])
  File "/home/william/detectron2/detectron2/utils/serialize.py", line 23, in __call__
    return self._obj(*args, **kwargs)
  File "/home/william/detectron2/detectron2/data/dataset_mapper.py", line 73, in __call__
    utils.check_image_size(dataset_dict, image)
  File "/home/william/detectron2/detectron2/data/detection_utils.py", line 73, in check_image_size
    "mismatch (W,H), got {}, expect {}".format(image_wh, expected_wh)
detectron2.data.detection_utils.SizeMismatchError: mismatch (W,H), got (2080, 1560), expect (4160, 3120)

The size mismatch error is always a factor of 2 but when printing the size of an image and its reference in the json they actually match :

d = DatasetCatalog.get('flowchart')
print(d[0]['width'])
print(d[0]['height'])

1303
2000

from PIL import Image
im = Image.open(d[0]["file_name"])
print(im.size)

(1303, 2000)

Anybody encountered this issue ?

[vylly]

That was my bad on this one, miscommunicating with the coworkers on how the dataset & json was build.

[XiaoJiNu]

@vylly hi, I miss the same problem but what makes the problem? Whether the size of the image in json is not right?

[vylly]

@XiaoJiNu Yes exactly, in my case the issue was that we modified some of the image sizes without updating the json file so there was a difference between what was written in the json and the actual size of the images

[morestart]

hi this is my error , do you know how to solve it?

detectron2.data.detection_utils.SizeMismatchError: Mismatched (W,H) for image /content/data/Images/137.jpg, got (3264, 2448), expect (2448, 3264)

[joeljosephjin]

I too am getting the same exact error. And on rerunning the code several times, it sometimes passes without showing this error.

hi this is my error , do you know how to solve it?

detectron2.data.detection_utils.SizeMismatchError: Mismatched (W,H) for image /content/data/Images/137.jpg, got (3264, 2448), expect (2448, 3264)

[morestart]

I too am getting the same exact error. And on rerunning the code several times, it sometimes passes without showing this error.

hi this is my error , do you know how to solve it?

detectron2.data.detection_utils.SizeMismatchError: Mismatched (W,H) for image /content/data/Images/137.jpg, got (3264, 2448), expect (2448, 3264)

i use rectLabel to generate the coco json file, it worked.I never received this error again

[Jeyakumar-johnny-jonathan]

Mismatched (W,H) for image /content/Mask_RCNNtrain/IMG_0855.jpeg, got (4032, 3024), expect (3024, 4032)

[CarlBhy]

i have solved this question,You can take a look through this link！
#2278 (comment)

[Sendeman]

Mismatched (W,H) for image /content/Mask_RCNNtrain/IMG_0855.jpeg, got (4032, 3024), expect (3024, 4032)

Hi, in my case it was due to exif metadata which rotates the image. detectron2 uses Pillow to load in the data during shape checkin which does the auto rotation, cv2.imread() however doesnt. To fix this take a look at this answer! https://stackoverflow.com/questions/19786301/python-remove-exif-info-from-images