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?
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)
