This texture was generated in Filter Forge, a Photoshop plugin that allows you to create your own filters.
Often when you threshold e.g. a distorted gradient or bevelled shapes (frames in particular) you wont have the same thickness due to the stretching/dist
This small snippet shows how to make strokes/outline
The upper part (red), shows the trivial simple approach that produces non uniform stroke. The lower part (green) shows the essentials of this snippet: uniform stroke.
LIMITATIONS: The approach can reduce fine details in more complex inputs. Due to the high pass step, sharp corners gets rounded, see variation 3 (this is what you see if you uncheck Ellipse/Rounded Rect). Also due to the high pass step, close feature strokes may "melt" together as seen in the last variation (relative to the thickness).
Stroke Thick Line Shape Figure Uniform Outline Equal Ellipse Rounded Rectangle Frame