public static unsafe SKPixmap FrequencyFilter(this SKImage image, int min, int max)
{
ComplexImage complexImage = image.ToComplexImage();
complexImage.FastFourierTransform();
FrequencyFilter filter = new FrequencyFilter(new FrequencyRange(min, max));
filter.Apply(complexImage);
complexImage.ReverseFastFourierTransform();
SKPixmap pixmap = complexImage.ToSKPixmap(image);
return(pixmap);
}