The barcode label is a very detailed piece of technology. Just a quick look at a the mysterious numbers, different shape bars and numbers and it really does seem another language. It is not therefore surprising that a perfect scan is not quite a straight forward as we sometimes think.
All the data within the barcode label is read by moving a spot of light across the barcode (produced by the scanner), starting in the white space before the first bar and moving through all the bars and spaces to the white area at the other end of the code. If the light trails off this area the barcode is not read correctly.
Supermarket beam scanners
Supermarket checkouts use moving beam scanners. There is no way of controlling the path over the beam sufficiently to ensure that the beam will move horizontally across the code. So, it must follow the wider the code is, the greater the chance of the beam going off the top or bottom before scanning the entire width. Therefore it follows that by increasing the height of the barcode label, the chances of a good scan are improved.
To enhance the barcode label reading a magnification factor is used. This facility increases height and width in order to scale the size of the barcode.
How contrast effects barcode label scanning
As well as height and width, another factor to take into account is contrast between the lines and numbers and the background. We tend to think of barcodes as black and white but dependant on printing – there can be different shades of grey – and with advances in technology, barcode labels can be created in more or less any colour you like.
Black bars and white spaces will forever offer the best contrast for effective scanning. Whereas most colours will produce an effective scan, there are some that do not create enough contrast between foreground and background. In summary, good bar line colours are black, green, blue, and dark brown while good space colours are white red yellow and orange.