# Source code for rl_coach.filters.observation.observation_to_uint8_filter

    #
    # Copyright (c) 2017 Intel Corporation
    #
    # Licensed under the Apache License, Version 2.0 (the "License");
    # you may not use this file except in compliance with the License.
    # You may obtain a copy of the License at
    #
    #      http://www.apache.org/licenses/LICENSE-2.0
    #
    # Unless required by applicable law or agreed to in writing, software
    # distributed under the License is distributed on an "AS IS" BASIS,
    # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    # See the License for the specific language governing permissions and
    # limitations under the License.
    #

    import numpy as np

    from rl_coach.core_types import ObservationType
    from rl_coach.filters.observation.observation_filter import ObservationFilter
    from rl_coach.spaces import ObservationSpace

    class ObservationToUInt8Filter(ObservationFilter):
        """
        Converts a floating point observation into an unsigned int 8 bit observation. This is
        mostly useful for reducing memory consumption and is usually used for image observations. The filter will first
        spread the observation values over the range 0-255 and then discretize them into integer values.
        """
        def __init__(self, input_low: float, input_high: float):
            """
            :param input_low: The lowest value currently present in the observation
            :param input_high: The highest value currently present in the observation
            """
            super().__init__()
            self.input_low = input_low
            self.input_high = input_high

            if input_high <= input_low:
                raise ValueError("The input observation space high values can be less or equal to the input observation "
                                 "space low values")

        def validate_input_observation_space(self, input_observation_space: ObservationSpace):
            if np.all(input_observation_space.low != self.input_low) or \
                    np.all(input_observation_space.high != self.input_high):
                raise ValueError("The observation space values range don't match the configuration of the filter."
                                 "The configuration is: low = {}, high = {}. The actual values are: low = {}, high = {}"
                                 .format(self.input_low, self.input_high,
                                         input_observation_space.low, input_observation_space.high))

        def filter(self, observation: ObservationType, update_internal_state: bool=True) -> ObservationType:
            # scale to 0-1
            observation = (observation - self.input_low) / (self.input_high - self.input_low)

            # scale to 0-255
            observation *= 255

            observation = observation.astype('uint8')

            return observation

        def get_filtered_observation_space(self, input_observation_space: ObservationSpace) -> ObservationSpace:
            input_observation_space.low = 0
            input_observation_space.high = 255
            return input_observation_space