'Augmenter body'

def __call__(self, src):

    alpha = (1.0 + random.uniform((- self.contrast), self.contrast))
    gray = (src * self.coef)
    gray = (((3.0 * (1.0 - alpha)) / gray.size) * nd.sum(gray))
    src *= alpha
    src += gray
    return [src]
