Outline areas in Gimp, to laser with Glowforge

We were making a cutting board for a wedding and wanted to include a graphic that was part of the invitation. Unfortunately the graphic had lots of colors which don’t always show up so well on the Glowforge.

We tried it just as is, lasering it onto a test cypress board:

As you can see, the man fades into the landscape. So we thought we would just outline the colors, and since I know people ask this question when Lasering maps, I thought I would show the steps I did in Gimp.

  1. Use the Select By Color Tool, choose one color to start. I choose the color of the plants in the foreground. You should see the dotted selection line showing around what you choose to select.
  2. Grow your selection. In the Select menu choose Grow… I choose to grow it by 3 to have lines 3 thick.
  3. Select the Paint tool, and set the paint brush size to be HUGE, I choose 800
  4. Quickly paint black over the whole image, with the huge paint brush it takes no time. The color of the plant is now Black, as is any other part of the image that has that color.
  5. On the Select Menu, choose Shrink… Shrink it by 3 to go back to the original size selection
  6. Select the Eraser tool with the huge 800 size brush again, erase the whole canvas. It will only erase the parts of the image that were the color you choose in Step 1.
  7. Repeat steps 1-6 for each color.

I did this and lasered the results on the back of the test board and got this:

We were not 100% satisfied with the results, so we combined both and got this (on a maple board, that will match our final project):

here is the image on the cutting board, but no finish applied yet:


Not a bad result, and an interesting workflow.

In the future if you want to get a look at how an image might look when sent to the Glowforge use the desaturate command to convert it to greyscale. There are a few options in that tool that yield slightly different results, it’s worth playing around to see what you’re working with.

Then you can mess with the select by color and/or curves to really dial in the greyscale to get the result you’re looking for.


Kudos for staying with it.


Love the combo image! Congrats on how well it turned out.

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This turned out really nice!

Nice work! Thanks for the insight into GIMP. Very interesting and helpful

I use Gimp in much the same way all the time but I save each mask as a path and then export all the paths as an SVG. Each one will come into Inkscape as a path that you can fill with a different color and when you bring that into the GFUI you can set them up as different engraving settings of the different colors.



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