All About The UPC

Published: 06/13/18

PUTTING TOGETHER A UPC CODE FOR A CLIENT

First of all, the client needs to have their UPC number. Though Panda can generate the visual barcode itself, we cannot generate a numerical code for our clients.

We recommend using buyabarcode.com for clients that need to purchase a barcode.

GENERATING THE BARCODE

Though there are many website that allow you to generate barcodes, JF suggests using http://online-barcode-generator.net/ for the ease of use and the file format it can export to.

Once on the website, here are the simple steps to follow:

  1. Select your barcode type from the scroll-down list. Generally, this'll be UPC-A, though European clients may ask for an EAN-13.
  2. Enter the barcode in the "Enter contents" field. (JF recommends clicking more option and setting the scale to "Large.") Then click "Create."
  3. Your UPC code is now ready. Save it as an Illustrator EPS or SVG for the next step. (Then you can "cut it down," just because it's cool.)

So now you have your UPC, that's great! We'll now make sure that our client can link it without any of the usual issues cropping up (namely rich black).

"FIXING" THE BARCODE

To fix the barcode, we'll use Illustrator. Once your file is open, here is what you must do (this applies for both the SVG or EPS version of the file).

  1. Set the color mode to CMYK. (It's very important to do this first.)
  2. Select the white background and delete it.
  3. Select the numbers and change their fill color to C: 0%, M: 0%, Y: 0%, K: 100%.
  4. Select the numbers and change their fill color to C: 0%, M: 0%, Y: 0%, K: 100%.
  5. Export as a PDF to be linked by your client.

Voilà! Your UPC should now be in pure black and ready to be approved by Panda.

ADDITIONAL INFORMATION ON UPCS AND THE TECH BEHIND IT

The background of a UPC can contain no more than 10% of Cyan, a mixture of magenta and yellow equaling no more than 50%, and 0% black (or key).

Please read below to understand the reasons for these limits on UPC inks.

What the laser 'sees'

Practically all scanners are based on a helium-neon laser light beam which "sees" the yellow and red process printing colors as light areas, and the blue and black colors as dark areas. Since the UPC decode is based on the time it takes the beam to cross the dark bars and the light spaces in between, it is obvious there must be sufficient color contrast between the bars and spaces. To the laser, a 100% process blue background would be indistinguishable from the black bars; but yellow and red background would be OK. So why 10% process blue as a "usually acceptable" screen in the "light" spaces between the bars? First, the blue dots in screens higher than 10% are usually of such a size that when the laser beam crosses them, it thinks it has begun to see a dark bar. This confuses the scanner, and it reports a no-scan. Second, when the blue dots butt against an actual dark bar, the scanner thinks the bar is wider than it actually is and again reports a no-scan.

Black and blue

Screens of black cause similar, but even greater, problems and thus are to be totally avoided. To attempt to use blue screens over 10% and any black is to take a high-risk gamble on scannability. Why is there a limit on yellow and red? While it is true that process yellow and red are good background colors for laser scanning of black and blue dark bars, don't overlook the effect of laying one ink down on another.

The ink problem

In the making of the film master used to generate the bars on the printing plate, the width of the bars is reduced to allow for bar width gain caused by the spread of the ink as it is absorbed into the paper. This bar width reduction (taken by shaving the bar edges) varies with the printing process and the paper. It is also affected by humidity, ink viscosity, heat treatment and other variables. When the black bars are printed on top of the red and/or yellow ink, the absorption capacity of the paper will have been reduced. The black ink will tend to spread as it goes onto the still wet yellow/red ink background. While there will be no contrast problem, the distance between the bars may be so reduced, or the bar edge become so irregular, that the symbol will not scan. This is known as an "ink trapping" problem. It has been found through experience that a limit of 50% in yellow and red, singly or in combination, minimizes these problems.

Remember, a UPC scanner needs:

Straight bar edges so the distances (thus time intervals) across the bars and spaces are exact. A good color contrast (solid black or blue on white) "excuses" and enables a scanner to read some symbols which would otherwise be unscannable due to irregular, too wide or too narrow bars. By the same token, straight edge bars of correct width will often "excuse" some otherwise unscannable color contrasts.

Scanner variance

Each brand, type, and model of scanner—even identical units— may vary in ability to "forgive" and decode out-of-spec symbols. Some non-laser beam wand scanners (used by retailers and wholesalers) may recognize symbols on which a laser unit completely strikes out, and vice versa. However the UPC specifications were not written around any one scanner, but around the entire technology. All scanners can read an in-spec symbol, and that is the criterion to use—not what can be gotten away with!

From: http://www.pips.com/acceptable_bar_code_background_colors.htm

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