PHOTO PREPARATION GUIDE · RASTERGO
Dithering for laser engraving: what it does and when to use it
Updated October 2026 · Free browser tool · photos stay on your device
Dithering converts continuous tones into a pattern of dots so a laser, which is effectively on or off, can suggest grey levels. Use one dithering step in your pipeline — either in your preparation tool or in the laser software, not both.
Why dithering exists
A laser does not print grey. It either marks a spot or it does not. Dithering fakes tonal range by varying how densely dots are placed, so the eye reads shading from a distance.
Common approaches
- Error-diffusion (Floyd–Steinberg, Jarvis/Judice/Ninke, Stucki): organic pattern, good for photos, spreads error to neighbouring pixels.
- Ordered / Bayer: regular grid pattern, predictable and fast, can look mechanical at low DPI.
Which one looks right depends on DPI, material and viewing distance. There is no universally best choice, and one that looks good on slate may look wrong on light wood.
Do not dither twice
If you export an already dithered file and your laser software applies another tonal conversion, the second pass works on dots instead of tones and the pattern breaks up. Pick one place for the conversion: either export a dithered PNG and import it in a pass-through mode, or export a continuous-tone PNG and let the laser software convert it. Check the image mode on import.
Practical check
View the export at 100% and then at the size it will be viewed from. Dithering that looks noisy at 100% often reads correctly at arm's length.
RasterGo prepares image files in your browser. Material previews are labelled digital simulations, not photographs of engraved pieces, and no power, speed or physical result is promised.