- Check the file for soft edges, an opaque background and low DPI
- Remove the background or harden the edges
- Set a white choke of 0.1–0.15 mm and print
1. Soft, semi-transparent edges
Photoshop feathers, drop shadows, glow effects and JPEG-to-PNG conversions leave pixels with 10–90 % opacity around the design. On screen they look like a smooth edge. The RIP treats any pixel with alpha above its threshold as “design” and prints white under it — so the halo is literally the shadow of your anti-aliasing.
- See it: in ZoroPrint Studio or the RIP, the item card shows “soft edges → white halo” when more than 2 % of visible pixels are semi-transparent.
- Fix it: press Fix. Alpha is snapped to 0 / 255 (hard edge). For shadows you actually want, keep them but expect a faint white base under them — that is physics, not a bug.
2. An opaque background
A JPG, or a PNG exported with a white or cream background, prints as a full rectangle: colour on the whole area and white under the whole area. Around the artwork you get a white box, not a halo.
- See it: the card says “opaque background → white box around the design”.
- Fix it: press Fix. The background is flood-filled from the border to transparent (tolerance 40), and the new edge is softened by one pixel.
3. No choke
Even with a perfect file, ink spreads a little on film and the white layer registers a fraction of a millimetre off the colour layer. The choke shrinks the white plane inside the colour edge so any misregistration shows colour, not white.
- Standard: 0.1–0.15 mm (3–4 px at 720 dpi). ZoroPrint defaults to 0.1 mm.
- Above 0.2 mm the edges of thin lines start to look washed out because the white no longer supports them — for hairlines use a smaller choke, not a bigger one.
