What is image mask?

[vvjn]

Hi, Can you tell me what the image mask (from path_to_train_img_mask and path_to_valid_img_mask below) is and what it is used for? Thanks.

python train_mmod.py \
 -data demo \
 -save_model demo_modelname \
 -path_to_train_img_feats train-resnet50-res4frelu.npy \
 -path_to_valid_img_feats val-resnet50-res4frelu.npy \
 -path_to_train_attr train_obj.npy \
 -path_to_valid_attr val_obj.npy \
 -path_to_train_img_mask train_obj_mask.npy \
 -path_to_valid_img_mask val_obj_mask.npy \
 -encoder_type transformer -decoder_type transformer --multimodal_model_type dcap

[ShaoDonCui]

I ran the preprocess.py but got this error, why? (base) C:\Users\cui\Desktop\my like code\DCCN-master>python preprocess.py -train_src train.lc.norm.tok.en -train_tgt train.lc.norm.tok.de -valid_src val.lc.norm.tok.en -valid_tgt val.lc.norm.tok.de -save_data demo Extracting features...

• number of source features: 0.
• number of target features: 0. Building Fields object... Building & saving training data... Traceback (most recent call last): File "C:\Users\cui\Desktop\my like code\DCCN-master\onmt\io\TextDataset.py", line 369, in iter raise StopIteration StopIteration

The above exception was the direct cause of the following exception:

Traceback (most recent call last): File "C:\Users\cui\Desktop\my like code\DCCN-master\preprocess.py", line 209, in main() File "C:\Users\cui\Desktop\my like code\DCCN-master\preprocess.py", line 194, in main train_dataset_files = build_save_dataset('train', fields, opt) File "C:\Users\cui\Desktop\my like code\DCCN-master\preprocess.py", line 128, in build_save_dataset return build_save_text_dataset_in_shards( File "C:\Users\cui\Desktop\my like code\DCCN-master\preprocess.py", line 96, in build_save_text_dataset_in_shards dataset = onmt.io.TextDataset( File "C:\Users\cui\Desktop\my like code\DCCN-master\onmt\io\TextDataset.py", line 76, in init for ex_values in example_values: File "C:\Users\cui\Desktop\my like code\DCCN-master\onmt\io\TextDataset.py", line 68, in example_values = ([ex[k] for k in keys] for ex in examples_iter) File "C:\Users\cui\Desktop\my like code\DCCN-master\onmt\io\TextDataset.py", line 55, in examples_iter = (self._join_dicts(src, tgt) for src, tgt in zip(src_examples_iter, tgt_examples_iter)) RuntimeError: generator raised StopIteration

[ShaoDonCui]

can you help me? thank you.