I use GIMP to export a PNG for engraving. I ensure that the resolution (200 dpi) gets saved in the image file. When I upload it to the Glowforge, the size is way off. Instead of 2.7 inches tall, it’s closer to twice that. How can I get the image to engrave at exactly the right size? What image resolution does Glowforge assume when it ignores what I specified in the PNG? Do I need to use some other file format?
96 dpi IIRC. (Yes this is a complete sentence Discourse.) 
(Somebody educate this program.)
Embed your image in a .svg (inkscape, AI, corel) for exact size and placement.
Hmm. I thought SVG was only for scoring and cutting. I want to engrave. Is there a way to engrave from an SVG?
Yes, embed an image or any closed filled vector shape.
Great, thanks. I will try putting the bitmap graphic into an SVG format. Not sure how to do that in GIMP yet. If anybody has any experience with that, I would love to hear about it.
It’s easier to import the image you made in gimp into Inkscape. You want to have all the editing except for scale already done before booting up Inkscape because many of the things you can do to that bitmap in Inkscape (flip, rotate, etc.) turn out badly in GFUI.
So you want to get it the way you want in gimp. Export it as png. Then open up Inkscape, import the image, place it and size it on your 20" x 12" document and save as SVG. Import that into GFUI.
Okay, thanks for the advice. I figured out how to bring the bitmap and the paths from GIMP into Inkscape, and then save all of it into a single SVG. Unfortunately, the GIMP paths were no longer aligned with the bitmap, because I had to export them from GIMP separately, and then import them separately. Requires manually dragging the vectors and bitmap together again in Inkscape.
I wish there were a simple way to do the whole vector cutout of a bitmap all in Inkscape, but I haven’t figured it out yet if there is.
In GIMP, I just use the magic wand tool to select the background, then invert the selection, then shrink the selection by a few pixels, then convert to a path. Super easy.
Is there an equally simple workflow in Inkscape, I wonder?
Actually, it is not a grammatically complete sentence. 
It would be if you replaced the 96 with something like “Use 96 DPI IIRC.” (although many would say you should spell out the IIRC). Nouns & verbs are kind of required for full sentences and implied ones don’t count 
Brevity is the soul of wit. 
(And yes, I realize that coming from me, that is incredibly ironic.)
Now that’s a complete sentence.
I bet Discourse didn’t yell at you
Does that imply you’re generally witless?
Discourse has been yelling at me from day one. (All those tutorials? I can’t do a damned thing without it telling me that it’s similar to something I’ve already posted.) 
And yes, it does.
yeah, that one is a real irritant. And the one where it warns you that you’ve already had several replies in the same thread and maybe you should let other people pipe in…even though there are 150 other replies…
If we continue this conversation, we’ll both see it. 
Yes Discourse doesn’t like conversations!
Discourse is actually all about conversations it’s one of their main features. 
“Conversations, not pages”
All these minor nags are just reminders to keep the conversation on topic and help moderate duplicate posts. If you’ve ever had to moderate a Sharepoint site at a large enterprise you know the pain.
@evansd2 I appreciate the info, but it appears that method of cutting out around an object only applies to vector objects. I am trying to cut out around an image object (raster). Inkscape appears not to be able to do this. When I use the fill tool, it doesn’t produce a vector boundary; it just fills in the pixels outside the image. Back to the drawing board.
– Will