def METHOD_NAME(self, data_shape):
    if self.nine_channels:
        new_ds = []
        for ds in data_shape:
            height, width = ds[:2]
            if height == -1 or width == -1:
                new_ds.append(ds)
                continue
            H = (height // 6) * 6
            W = (width // 6) * 6
            new_ds.append((H // 3, W // 3, 9))
        return new_ds
    return data_shape