    def _make_img_list(self):
        """ Creates a dictionary of lists of the acceptable images contained in lr_dir and hr_dir. """
        
        for res in ['hr', 'lr']:
            file_names = os.listdir(self.folders[res])
            file_names = [file for file in file_names if file.endswith(self.extensions)]
            self.img_list[res] = np.sort(file_names)
        
        if self.n_validation_samples:
            samples = np.random.choice(
                range(len(self.img_list['hr'])), self.n_validation_samples, replace=False
            )
            for res in ['hr', 'lr']:
                self.img_list[res] = self.img_list[res][samples]
Creates a dictionary of lists of the acceptable images contained in lr_dir and hr_dir.
ISR/utils/datahandler.py