How to decode first digit in EAN13?

[WojTec]

I have some EAN13, lets say 6 462456 178322. After digitalize I have:

Code:

101
0100011
0000101
0011011
0011101
0110001
0101111
01010
1100110
1000100
1001000
1000010
1101100
1101100
101

First digit is not coded directly in bars. So question is how to compute it, if I have binary data?

[Sir Rufo]

Have a Close Look at http://de.wikipedia.org/wiki/European_Article_Number

[WojTec]

Yes, I read this. First digit is not coded in barcode, but used to encode "left". Coded are digits 2-13 (each 7 bits + 11 bits for sentinels). So, I have 84 bits. Last 6 digits I can decode by lookup in code table for "right". But to know digits 2-7 I need to know first one. I don't have idea how to get it :(

[Sir Rufo]

Just compare with the Code-Table

Code:

101
0100011 - 4 U
0000101 - 6 G
0011011 - 2 G
0011101 - 4 G
0110001 - 5 U
0101111 - 6 U
01010
1100110 - 1 G
1000100 - 7 G
1001000 - 8 G
1000010 - 3 G
1101100 - 2 G
1101100 - 2 G
101

And after that u have UGGGUU GGGGGG and the Code-Table offers 6

So we have 6 462456 178322

qed

[WojTec]

Oh, now I see, thanks :-D