How to use CoreImage to create a smooth threshold filter?
<p>Are there existing filters that could be used as a smooth threshold? By this I mean that pixel values should be thresholded between two values, but the intermediate values are interpolated.</p>

<p>Basically, I'm trying to implement this:</p>

<p><a href="https://www.filterforge.com/wiki/index.php/Thresholds#Interpolation_.28.22Blending.22.29" rel="nofollow">https://www.filterforge.com/wiki/index.php/Thresholds#Interpolation_.28.22Blending.22.29</a></p>