suchenwi	But one basic question: in barcodes like Code 128 (EAN?), each digit is a black and a white bar, the added thickness of which two is constant, right?
 kroc	Richard: each digit (or letter for some barcodes) is a set of bars and spaces...
 suchenwi	How many?
 kroc	it depends of barcode type.
 kroc	Six per char for Code 128 for a total of 11 units.
 kroc	 Here is a sample :
	B == bar and S == space
	digit represents width.
	char == BSBSBS
	a = 121124
	b =  431111
	etc..
 kroc	 So, graphic representation will be:
	a = "X  X XX    "
	b = "XXXX   X X "
 kroc	To build the barcode, you join all char bars and spaces. It also need start and end symbol, sometimes an ending control char, and must respect minimum width requirements to be read.
 suchenwi	Ah - and for a quick shot one could draw canvas lines for the bars...
 suchenwi	Check digit too, if I remember right.
 kroc	 It's more accurate to draw on a photo image like that :
	foreach {bar space} $code {
	        set larg [expr ($bar * $unit)+$debut]
	        img-$nbimg put #000000 -to $debut 0 $larg $fin
	        set debut [expr ($space*$unit) + $larg]
	}
 suchenwi	Do you have a link to specifications of the bar-space width patterns?
 kroc	mb: to answer your question, ean8 and Code 128 aren't the same thing at all.
    * kroc checking... 
 kroc	http://www.ean-int.org
 kroc	http://www.barcodeisland.com/symbolgy.phtml