A QR code on a business card is usually a dead grey square in the corner — functional, anonymous, and the first thing the eye skips. A code with your face dithered through it does the same job while also being the reason someone picks the card up.
Print is less forgiving than screen. Everything below is about the gap between the two.
How to do it
Decide what the code should do
A link to your site or LinkedIn is the simplest and the shortest. The Contact card mode builds a vCard straight from name, phone and email and puts it in the code directly — no link, no server, saved to the phone on scan. That directness costs modules: every field is more characters, which means more modules and a smaller cell left for the picture. Keep a contact card to the few fields you actually want handed over, and use a link instead if the portrait needs more room than that leaves it.
Choose a portrait that survives one bit
Strong directional light, plain background, tight crop. Colour is discarded entirely, so a dark jacket against a dark wall becomes one shape. Check the picture in greyscale first; if you cannot tell where you end and the background begins, neither can the dither.
Dither for ink, not for screen
Printers spread ink slightly, which thickens dark areas and closes up fine gaps — an effect called dot gain. A dither that looks perfect on a monitor can turn muddy on uncoated stock. Bias a little lighter than looks right, and prefer Stucki or Jarvis–Judice–Ninke if the code will be printed small — their wider kernels spread the error further and hold their structure better than Floyd–Steinberg's tighter diffusion.
Size it at 2cm or more
As a rule of thumb a printed code wants around 2cm square to be read comfortably at arm's length, and more if people will scan it from further away. The ratio that matters is distance to size: roughly 10:1. A code read from 40cm needs about 4cm.
Keep the quiet zone
A QR code needs clear margin around it — four modules' worth — for a scanner to find its edges. Do not bleed it to the trim, do not tuck text against it, and do not let a background pattern run underneath. This is the single most common reason a printed code fails.
Proof on the real stock before you order
Print one at final size on the paper you intend to use, and scan it with a few different phones in ordinary indoor light. Matte and uncoated stock scatter more light and are more forgiving than gloss, which throws glare straight back at the camera. Do this before committing to a run of five hundred.
Why printed codes fail
- No quiet zone. The code runs into a border, an edge, or body text.
- Printed too small. Under about 2cm, phone cameras start to struggle at normal distances.
- Inverted. Light modules on a dark ground defeats some older scanners. Keep dark on light.
- Gloss varnish. A spot UV finish over a code produces glare exactly where the camera needs contrast.
- Dead link. The one failure no amount of print care fixes. Use a destination you will still control in five years.
A note on tracking
If you want to know how often the card actually gets scanned, point the code at a short link that redirects, rather than at the destination directly. That also means you can repoint a card you have already handed out. The trade-off is a server in the path — the picture is still dithered locally, but the link resolves through us.