evo.py 文件源码

def get_fitness(self, target):
        """
        Get fitness of the individual.
        This was calculated by RMS distance of histograms.

        Args:
            target: target image.

        Returns:
            the fitness value.
        """
        h = ImageChops.difference(target, self.im).histogram()
        return math.sqrt(reduce(operator.add,
                         map(lambda h, i: h*(i**2),
                             h, range(256)*3)) /
                            (float(target.size[0]) * target.size[1]))