Function _check_image_input

stable_baselines3/common/env_checker.py:57–92

Check that the input will be compatible with Stable-Baselines when the observation is apparently an image. :param observation_space: Observation space :param key: When the observation space comes from a Dict space, we pass the corresponding key to have more precise warning

(observation_space: spaces.Box, key: str = "")

def _check_image_input(observation_space: spaces.Box, key: str = "") -> None:
    """
    Check that the input will be compatible with Stable-Baselines
    when the observation is apparently an image.

    :param observation_space: Observation space
    :param key: When the observation space comes from a Dict space, we pass the
        corresponding key to have more precise warning messages. Defaults to "".
    """
    if observation_space.dtype != np.uint8:
        warnings.warn(
            f"It seems that your observation {key} is an image but its `dtype` "
            f"is ({observation_space.dtype}) whereas it has to be `np.uint8`. "
            "If your observation is not an image, we recommend you to flatten the observation "
            "to have only a 1D vector"
        )

    if np.any(observation_space.low != 0) or np.any(observation_space.high != 255):
        warnings.warn(
            f"It seems that your observation space {key} is an image but the "
            "upper and lower bounds are not in [0, 255]. "
            "Because the CNN policy normalize automatically the observation "
            "you may encounter issue if the values are not in that range."
        )

    non_channel_idx = 0
    # Check only if width/height of the image is big enough
    if is_image_space_channels_first(observation_space):
        non_channel_idx = -1

    if observation_space.shape[non_channel_idx] < 36 or observation_space.shape[1] < 36:
        warnings.warn(
            "The minimal resolution for an image is 36x36 for the default `CnnPolicy`. "
            "You might need to use a custom features extractor "
            "cf. https://stable-baselines3.readthedocs.io/en/master/guide/custom_policy.html"
        )


def _check_unsupported_spaces(env: gym.Env, observation_space: spaces.Space, action_space: spaces.Space) -> bool:  # noqa: C901