@manipulative
    def unsharp_mask(self, radius, sigma, amount, threshold):
        if not isinstance(radius, numbers.Real):
            raise TypeError('radius has to be a numbers.Real, not ' +
                            repr(radius))
        elif not isinstance(sigma, numbers.Real):
            raise TypeError('sigma has to be a numbers.Real, not ' +
                            repr(sigma))
        elif not isinstance(amount, numbers.Real):
            raise TypeError('amount has to be a numbers.Real, not ' +
                            repr(amount))
        elif not isinstance(threshold, numbers.Real):
            raise TypeError('threshold has to be a numbers.Real, not ' +
                            repr(threshold))
        r = library.MagickUnsharpMaskImage(self.wand, radius, sigma,
                                           amount, threshold)
        if not r:
            self.raise_exception()
Sharpens the image using unsharp mask filter. We convolve the image
dataset/ETHPy150Open dahlia/wand/wand/image.py/BaseImage.unsharp_mask