You can use the Inkscape auto-trace. (Believe it’s called Trace Bitmap, but I’m away from the computer.)
You can also generate a cut line on a raster image using the Glowforge Trace tool, and it’s a good one.
Instructions for using it here:
What Jules said.
If your image doesn’t want to trace very well due to specifics like contrast and whatnot, go back to gimp/ps/whatever and process it until it’s ready to be traced (edge detect and whatnot can help here) Import your newly over processed image into the same svg. Snap your good image to your over processed one, trace away.
Delete overprocessed garbage image from the svg, and now you have nice vector paths overlaid exactly on your “good” image, and you’re in business.
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@Jules Yes, the trace tool built into the Glowforge is quite nice, but it doesn’t (yet) include any binary morphology filters, such as dilate (grow), erode (shrink) or skeletonize. I have implemented all these filters before, and they’re all well-documented in the literature, but just not part of Glowforge yet. I will keep trying to find a good workflow, though, and when I do, I will share it with the community. Thanks for your suggestions.
Inkscape then. (Unless you own Illustrator or CorelDraw or Affinity Designer. You can use Offset to morph your outlines once you have them created.)
At least you’ve eliminated a few that won’t work for you.
You might be amazed/amused at the level of control Discourse allows. Here’s an excerpt of the settings for the (non-GF) site I manage…
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Thanks for all the helpful suggestions!
@will_bain, were you able to upload your design at the size you expected?
@jaz Yes, I finally figured it out. It’s a complicated workflow involving GIMP and Inkscape, because of a bug in Inkscape in which it refuses to read in the image resolution during import, even if you check the box.
In GIMP, I make sure the image has a blank, white background, and save the image at 90 dpi, because that’s all Inkscape can understand.
After importing it into Inkscape, I scale the image using a simple ratio based on the 90 dpi. Next, I use the trace bitmap tool in brightness cutoff mode and a threshold of 0.99, making sure to check the Invert image checkbox.
This results in very few paths, and I can easily delete all but the one or two I want if I make them all colored outlines with no fill and list them in the Objects dialog pane. Then I usually do an outset on the remaining path(s) to give a little extra room around the engraved image. The resulting file contains the bitmap to engrave and the cut path, and Glowforge brings it all in together at the correct size.
– Will Bain
Thanks for your reply – I’m glad it’s working. If you run into anything else, please post a new topic.