I was in hospital today and given a bracelet with a bar code, a 2D matrix and, in clear text, my name, the bar code number, date of birth, and age.

Looking at the 2D matrix, i noticed that every 4 "pixels" that formed a checkerboard pattern, there seem to be some small, black "blotches" inside the white pixels - but only when there was a checkerboard quadruple, not when there is one white next to three black pixels in an L shape. The blotches seem similar, but are not exactly similar. The rest of the print is razor sharp, so I highly doubt it's a hardware problem with the printer.

Would this be a "bug" somewhere in the software chain noone noticed or is this somehow an intentional feature?

The 2d Matrix with small subdots in "checkerboard" quadruples Detail of said matrix

P.S. For the 5 different checkups, 4 medical staff members asked me for my birthdate and typed it in, only one actually scanned the bracelet - but the old-fashioned barcode part of it. P.P.S. The data matrix encodes (according to the scanner app I have) "AC182495717", which is not the number the bar code encodes (a 10-digit decimal number starting with 10000)

  • I think this is the wrong place to put this question, try stackoverflow or a stackexchange that's more relevant to this question. I don't think there's anything to do with UX in this question Jun 23, 2023 at 21:28
  • Thx. I searched and most Matrix code printing questions turned up on UX.stackexchange - though I doubted myself.
    – IIVQ
    Jun 24, 2023 at 8:42
  • Huh? That's interesting. I could look into the spec to find out why those notches are there btw. I've noticed that most times when the "close question" hammer is used is on platform/app specific questions. Jun 24, 2023 at 8:54
  • 1
    I’m voting to close this question because it’s off topic.
    – jazZRo
    Jun 26, 2023 at 16:44

1 Answer 1


OK, so I did some research, I think your first hunch about this being a "bug" or at the least, an issue with the printer. From my understanding the scanner will probably just ignore the small artifacts. It's more interested in the blocks of data.




Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.