In order for the job control software to turn your design into tool paths, it needs to be a vector drawing. If you aren’t familiar with what a vector drawing is or the type of software you need to create and edit one, check out our Getting Started with Laser Cutting Tutorial.
To convert a graphic image to a vector file we will:
- Isolate desired part of the image
- Simplify the graphic
- Import to Inkscape
- Trace the Bitmap
Isolate the Desired Part of the Graphic
For this example, we will be using the whole image, but if you want to use only part of the image, it's easiest to do this while it's still a graphic. When we import our modified graphic into Inkscape and trace it, the entire image will be traced. So cut out anything unwanted at this step.
Simplify the graphic
The first step to converting a graphic image is to isolate the part of your image that you want to convert to a vector. The best images have high contrast between the background and the portion of the image you want to convert. In this example, we will use a simple image of a laser caution symbol. When creating a trace of a graphic its best to remove all unneeded portions of the file, and make sure the contrast between the background and foreground are as high a possible.
We’ll start by opening the drawing in Gimp. You could leave the white background, but if you can remove everything unwanted down to the Alpha layer, you can get better results. We will remove the white background by doing a magic wand selection and deleting it.
Note: If your background remains white, select Layer > Transparency > Add Alpha Channel
Next, we will remove the yellow from the graphic image. I will use the colour picker tool to select the yellow portions of the drawing and delete them. There is a bit of gradient yellow near the edges where the jpeg has blended the colours. It's good to click around with the colour picker and remove most of these so you get a good mask later on.
Its best to have as high contrast as possible, so we will darken the remaining portion of the drawing. You can do this by controlling brightness and contrast, or with the dodge/burn tool with a big brush. Using the Dodge/Burn tool, left click will lighten, Ctrl+Left Click will darken.
Now is a great time to correct any imperfections that may have occurred while editing the graphic. It doesn’t need to be perfect though so don’t sweat the small stuff, the outline is what is most critical.
Export your graphic as a .png or .jpeg.
Import Into Inkscape
Open a new document in input and select “Import”.
When you import an image you will have the option to link or embed it. We aren’t going to be keeping the graphic image in the vector file because it can corrupt our vector. So the best way is to choose “link”.
Trace the Bitmap
Next, we need to trace the bitmap. The trace function creates a vector copy of your graphic image. With the graphic image selected, go to Path > Trace Bitmap. You will see the following dialogue box:
There are multiple ways to accomplish the trace, and the most effective way will be different for each image. We typically use the brightness cutoff scan. When adjusting the threshold you will notice that at a certain level you start to lose detail. We recommend increasing the threshold until you see you're losing your desired shape in the preview, then reduce it by about 25%. This is usually a pretty good middle ground. Under the options tab, you may want to uncheck “Smooth Corners”.
The image on ‘top’ is your new vector! Sometimes its hard to tell the difference. You should expect to see a little rounding over sharp edges if this is a problem for your design you should make your graphic very large before doing the trace. You can now change the fill colour or the edge colour to create cuts or engravings.
The finished product! We’ve changed the vector to have no fill and made the stroke a 0.01mm thick red line. Now its ready to cut!
If you want to learn more about using a laser cutter, we have a whole category of Laser Cutting Tutorials! If you have a great file ready to cut, we now offer a Laser Cutting Service. Additive manufacturing more your thing? Head on over to our 3D Printing Tutorials section to learn all about it!