Faces turn into black masks, hair becomes a solid patch, the whole piece is heavier than the screen. Work through the causes in order.
Reviewed by the Vextrify team, tested in our own laser workshops · Updated · How we test
Try Vextrify freeWork from the file to the machine. Fix the tone of the image first, because it costs nothing to change. Check the line interval second. Only then spend scrap material on a test grid. Changing the machine before you have fixed the file leaves the real cause in place.
A photo whose shadows are already near black has no room to get lighter on the material. Dark hair, a dark jacket and a night scene turn into solid patches after dithering, because every dark tone becomes dense dots that merge. Open the live preview in Photo Studio, pick the profile for your material, which sets starting brightness, contrast and gamma, and raise the shadows until detail is visible in the dark regions.
If the line interval is smaller than the laser's spot, neighbouring lines overlap and every tone burns darker than intended. The interval in mm is 25.4 divided by DPI, so 254 DPI is 0.1 mm. Compare that with your spot size and widen the interval if the lines overlap. The right figure for your machine comes from a test grid.
Dot gain means the burn spreads past the dot, so the engraving is always darker than the screen. A file prepared for light birch will be too heavy on a material that darkens easily, and a file prepared as a positive will look wrong on dark acrylic, where the mark is lighter than the surface. Pick the profile that matches the material, compare dithering methods in the preview, and use Invert for dark materials.
If the file and spacing are right and the result is still too dark, the burn itself is too strong for this material. Engrave a material test grid on a scrap piece, a matrix of speed and power fields, choose the field that gives the tonal range you want and save it. This is the only place the numbers should come from. If the result is flat and grey instead of dark, see the page on muddy photo engraving.
Dot gain: the burn spreads past each dot, so tones come out darker than they look on screen. A line interval smaller than the laser's spot makes it worse. Lighten the file and check spacing before you change machine settings.
Only after the file and the line interval are right, and then by testing on scrap. Copying a power figure from another machine rarely works, since it depends on the laser and the material.
Dark tones in the source become dense dots that merge after dithering. Raise the shadows in the preview until detail shows in the dark areas.
No. A muddy result is flat and grey with weak contrast. There is a separate page for it.