How do I take an image with shadows/highlights and create a B&W version?

Question

I've got this image:

Grayscale: https://www.bungie.net/common/destiny2_content/icons/d514846e22682a17cea973e666a80277.png

Color: https://www.bungie.net/common/destiny2_content/icons/5fc6477c6e7f302b27819a276c13d72a.png

I'd like to go from this rendered PNG into something black and white. For example, imagine that the "polished metal" portions of the image are one color, and the "unpolished" portions of the image are the other.

I generally will try to use the "Levels" tool to do the best job I can, but what I find is that some of the highlights overlap with the same colors as some of the shadows. This leads to a lot of manual retouching that I'd like to avoid.

I've found that a selective Gaussian blur can make the edges more distinct, and the larger areas more homogeneous, but it isn't quite enough to solve the problem.

In the long term, I'd like to automate the whole workflow in something like ImageMagick or a GIMP Script or similar, as there are a lot of these images and Bungie adds more over time. So ideally, I don't have to do a lot of eyeballing in order to get something that looks good.

Can anyone suggest a way to reduce these grayscale images to black and white, preserving the detail, while avoiding manual action and causing weird shadow/highlight overlap artifacts?

Answer 1

One waterproof trick exists: Redraw it. Do it in a vector program. You can there use extrusions to get the apparent 3D depth + shadows + highlights, if they are needed. Or color all only black and white, if you want perfectly flat BW result like logos often must be.

Raster versions (JPG, PNG) can be got by rasterizing to the wanted resolution and size.

As said, this works. But one must have practiced a while to make a vector drawing program to obey his will.

Automation? Unfortunately this method does not have that possibility except in case you can program some clever artificial intelligence application for the job.