How to create an Inner Glow node effect The Inner Glow effect is a filter that allows to soften the edge while keeping a clear line of the main silhouette at his center. It is heavily used by Blizzard and many other stylized studios to project decorations and text to an high poly sculpture with a stylized crack look like if a dagger was used to sculpt it.
Michael Vicente has made a tutorial about this technique in a PDF: https://www.pearltrees.com/s/file/preview/139604217/OrbBevelTIP.pdf or in a video: https://youtu.be/eGHU8DI6fo4?t=5183

I try to achieve this:



It is important that we get only thin lines and not holes in more complex and wider areas. If we look at the displacement horizontally it should look like a V with a thin tipping point.



And here is what he gets by projecting it, as you can see there is just a think line at the center and the depth is flat:



The final result after using the Polish modifier of ZBrush:



The source image for your tests:



With the Inner Glow effect:
Use the Erode Node

A simple Dilate/Erode node in Threshold mode with "Distance" set to the same value as "Edge" does exactly the right thing.


With the math node "Power" afterwards the result matches the image from the tutorial perfectly.



Additional explanation

Linearity of the gradient

The Threshold mode of the Dilate/Erode node has a linear falloff. Here is a proof:
In the viewer-result you see the texture above and the output of the erode node below.

Congruence of the results

Here is a proof that the result of photoshop's inner glow effect is the same as the result of my proposed node graph above. The differences still visible are caused by different image formats and scaling blurriness.