def image_path_from_index(self, index):
        """
        Construct an image path from the image's "index" identifier.
        """
        # set the prefix
        prefix = self._image_set

        image_path = os.path.join(self._data_path, prefix, index + self._image_ext)
        assert os.path.exists(image_path), \
                'Path does not exist: {}'.format(image_path)
        return image_path

        Construct an image path from the image's "index" identifier.
        
lib/datasets/nthu.py