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Barcode recognition with JavaScript - Demo: http://bit.ly/djvUoy

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get_barcode_from_image.js
JavaScript
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/*
* Copyright (c) 2010 Tobias Schneider
* This script is freely distributable under the terms of the MIT license.
*/
 
(function(){
var UPC_SET = {
"3211": '0',
"2221": '1',
"2122": '2',
"1411": '3',
"1132": '4',
"1231": '5',
"1114": '6',
"1312": '7',
"1213": '8',
"3112": '9'
};
getBarcodeFromImage = function(imgOrId){
var doc = document,
img = "object" == typeof imgOrId ? imgOrId : doc.getElementById(imgOrId),
canvas = doc.createElement("canvas"),
width = img.width,
height = img.height,
ctx = canvas.getContext("2d"),
spoints = [1, 9, 2, 8, 3, 7, 4, 6, 5],
numLines = spoints.length,
slineStep = height / (numLines + 1),
round = Math.round;
canvas.width = width;
canvas.height = height;
ctx.drawImage(img, 0, 0);
while(numLines--){
console.log(spoints[numLines]);
var pxLine = ctx.getImageData(0, slineStep * spoints[numLines], width, 2).data,
sum = [],
min = 0,
max = 0;
for(var row = 0; row < 2; row++){
for(var col = 0; col < width; col++){
var i = ((row * width) + col) * 4,
g = ((pxLine[i] * 3) + (pxLine[i + 1] * 4) + (pxLine[i + 2] * 2)) / 9,
s = sum[col];
pxLine[i] = pxLine[i + 1] = pxLine[i + 2] = g;
sum[col] = g + (undefined == s ? 0 : s);
}
}
for(var i = 0; i < width; i++){
var s = sum[i] = sum[i] / 2;
if(s < min){ min = s; }
if(s > max){ max = s; }
}
var pivot = min + ((max - min) / 2),
bmp = [];
for(var col = 0; col < width; col++){
var matches = 0;
for(var row = 0; row < 2; row++){
if(pxLine[((row * width) + col) * 4] > pivot){ matches++; }
}
bmp.push(matches > 1);
}
var curr = bmp[0],
count = 1,
lines = [];
for(var col = 0; col < width; col++){
if(bmp[col] == curr){ count++; }
else{
lines.push(count);
count = 1;
curr = bmp[col];
}
}
var code = '',
bar = ~~((lines[1] + lines[2] + lines[3]) / 3),
u = UPC_SET;
for(var i = 1, l = lines.length; i < l; i++){
if(code.length < 6){ var group = lines.slice(i * 4, (i * 4) + 4); }
else{ var group = lines.slice((i * 4 ) + 5, (i * 4) + 9); }
var digits = [
round(group[0] / bar),
round(group[1] / bar),
round(group[2] / bar),
round(group[3] / bar)
];
code += u[digits.join('')] || u[digits.reverse().join('')] || 'X';
if(12 == code.length){ return code; break; }
}
if(-1 == code.indexOf('X')){ return code || false; }
}
return false;
}
})();

It does not return the left most number 5 in your example. How do i get that? I need to have that in order to be able to do an EAN checksum check

This code is great!
If you need a more accurate barcode scanner, try http://manuels.github.com/unix-toolbox.js-exact-image/demo/

manuels - I really like your code. Can you advise though, how do you increase the memory size as if you take a photo with an iphone 5 for example it complains about a memory issue?

I looked through this code when I started working on my barcode reader, it's nice to see that I understand
more of it now.
I have a demo of mine up if you want to take a look at it.
http://eddiela.github.io/BarcodeReader/demo.html

i need clear java script code for bar code scanner .because i am struggling where i have to pass my source image and i need to implement in mobile ...so any one can help me ....

Hi EddieLa ,

please post the file DecoderWorker.js of your code

Just copy the link and replace the htm file with the js file. Here is the link:
view-source:http://eddiela.github.io/BarcodeReader/DecoderWorker.js

I've used this to build a webcam barcode scanner

https://github.com/tonylampada/barcodescanner/tree/gh-pages

Live demo here:
https://github.com/jhuckaby/webcamjs/issues/9

Doesn't work that great (at least with my webcam)

It can only scan big images with not-so-long barcodes.

Any ideas on how to improve it?

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