@manipulative
    def gamma(self, adjustment_value, channel=None):
        if not isinstance(adjustment_value, numbers.Real):
            raise TypeError('expecting float, not ' + repr(adjustment_value))
        if channel in CHANNELS:
            library.MagickGammaImageChannel(self.wand,
                                            CHANNELS[channel],
                                            adjustment_value)
        elif channel is None:
            library.MagickGammaImage(self.wand, adjustment_value)
        else:
            raise ValueError(repr(channel) + ' is an invalid channel type'
                             '; see wand.image.CHANNELS dictionary')
        self.raise_exception()
Gamma correct image.
dataset/ETHPy150Open dahlia/wand/wand/image.py/Image.gamma