def __call__(self, dataset_dict):
        """
        Args:
            dataset_dict (dict): Metadata of one image, in Detectron2 Dataset format.

        Returns:
            dict: a format that builtin models in detectron2 accept
        """
        dataset_dict = copy.deepcopy(dataset_dict)  # it will be modified by code below
        file_name = dataset_dict['file_name']
        semseg_name = dataset_dict['sem_seg_file_name']
        image = Image.open(file_name).convert('RGB')

        dataset_dict['width'] = image.size[0]
        dataset_dict['height'] = image.size[1]

        if self.is_train == False:
            image = self.transform(image)
            image = torch.from_numpy(np.asarray(image).copy())
            image = image.permute(2,0,1)
            
        semseg = self.read_semseg(semseg_name)
        semseg = torch.from_numpy(semseg.astype(np.int32))
        dataset_dict['image'] = image
        dataset_dict['semseg'] = semseg
        return dataset_dict

        Args:
            dataset_dict (dict): Metadata of one image, in Detectron2 Dataset format.

        Returns:
            dict: a format that builtin models in detectron2 accept
        
datasets/dataset_mappers/bdd_semseg_dataset_mapper.py