Hi guys, I did some work in inkscape by changing the photo in filters and then used it to laser engrave into wood. Now I wanted to make the same effect for another photo but for the love of god I have absolutely no idea how I did it. Spent the last 3 hours going through filters and things but in vain. Can someone archieve the same finish I did the first time ? Looks like I used draw pencil effect, but is is just too dim. Here is how it looks

Hi-

That looks like some kind of edge detecting.
Can be achieved with either the convolve matrix (effect looks same at every zoom level, not scaling with the object) or by some difference of a blurred copy and the original.

Don't have it right at hand but it's easy to rig one.

In the mean time check out this topic, which you may find interesting:
halftone filter templates

Here are the two mentioned edge detecting filters:
svg source