First up, this requires some awareness of the difference between raster and vector images
Raster files are composed on pixels., eg. a normal photograph. In this case the format was JPG. Vector files use mathematical equations to make geometric chapes, lines, and curves with fixed points on a grid to produce an image. A common vector format is SVG.
Raster images are challenging and require more preparation before engraving or etching them with a laser cutter. You need to start with a photo with lots of contrast, eg. with a pure white background and pale clothes to contrast darkish hair (or trim the photo as I did).
One technique is error diffusion raster (Stucki, Jarvis, FloydSteinberg). The darker the grayscale value, the denser the points are set. The point size remains unchanged.
I'm a GIMP user (open source), not a Photoshop user. For my needs I found a couple of good tutorials online:
GIMP tutorial- Scale image to 300 px/inch
- Convert to black and white
- Histogram adjusted for good range of dark and light areas
- Adjust colour levels histogram towards the centre
- Adjust colour curves to boost the contrast
- Apply sharpening
After the GIMP tutorial I then applied this YouTube Lightburn tutorial:
- import and select the image
- tools > adjust image Alt + I
- Best image mode > Jarvis or Stucki
- DPI – approx 300
- To sharpen:
- Enhance radius: 25
- Enhance amount: 100
- Lighten the face and remove background dots:
- Brightness: 7
Note that the Preview normally looks poor and can be safely ignored! But you can get the time estimate through Preview.
After treatment with the two tutorials:
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