cuter44/ISBN13Parser.js

## demo.html
<!DOCTYPE html>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <script src="ISBN13Parser.js"></script>
  </head>

  <body>
    <input type="file" accept="image/*" onchange="loadAndParse(this);"/>
    <script>
      var parser = new ISBN13Parser();

      function loadAndParse(input)
      {
        console.log(input.value);

        var reader = new window.FileReader();
        reader.onloadend = function(){
          var img = new Image();
          img.src = this.result;
          alert(parser.parseImage(img));
        };

        reader.readAsDataURL(input.files[0]);
      }

    </script>
  </body>
</html>

## ISBN13Parser.js
/** ISBN-13 decoder
 * author by galin<cuter44@foxmail.com>
 * free to use if reserve the author info.
 */

function ISBN13Parser(){
  this.sResult = null;
  this.iaResult = null;
  this.baResult = null;
  this.thresold = 80;

  this.cb = (function (){
    var a = new Array();

    a[13]=0; a[39]=0; a[114]=0;
    a[25]=1; a[51]=1; a[102]=1;
    a[19]=2; a[27]=2; a[108]=2;
    a[61]=3; a[33]=3; a[ 66]=3;
    a[35]=4; a[29]=4; a[ 92]=4;
    a[49]=5; a[57]=5; a[ 78]=5;
    a[47]=6; a[ 5]=6; a[ 80]=6;
    a[59]=7; a[17]=7; a[ 68]=7;
    a[55]=8; a[ 9]=8; a[ 72]=8;
    a[11]=9; a[23]=9; a[116]=9;

    return(a);
  })();

  this.parseImage = function (img)
  {
    return(
      this.parseCanvas(this.img2Canvas(img))
    );
  }

  this.parseCanvas = function (cvs)
  {
    this.baResult =
      this.parseBits(this.binarize(this.discolor(cvs)));
    this.iaResult = this.decodeBits(this.baResult);

    var sResult = "";
    for (var i=0; i<13; i++)
      sResult = sResult.concat(this.iaResult[i]);
    this.sResult = sResult;

    return(this.sResult);
  }

  this.decodeBits = function (bits)
  {
    var offset = 3,
        decoded = new Array(13);

    for (var i=1; i<=6; i++)
    {
      var b = 0;
      for (var j=0; j<7; j++)
        b = (b<<1)+bits[offset++];
      decoded[i]=this.cb[b];

      //console.log(b.toString(2) + " -> " + decoded[i]);
    }

    offset = 50;
    for (var i=7; i<=12; i++)
    {
      var b = 0;
      for (var j=0; j<7; j++)
        b = (b<<1)+bits[offset++];
      decoded[i]=this.cb[b];

      //console.log(b.toString(2) + " -> " + decoded[i]);
    }

    decoded[0] = 9;

    return(decoded);
  }

  this.parseBits = function (cvs)
  {
    var w = cvs.width,
        h = cvs.height,
        w_mid = Math.floor(w/2),
        h_mid = Math.floor(h/2),
        ctx = cvs.getContext("2d"),
        data = ctx.getImageData(0, h_mid, w, 1).data,
        edge_l, edge_r, wh_l, wh_r, ln_found;

    wh_l = wh_r = 0;
    edge_l = edge_r = w_mid*4;
    ln_found = (data[4*w_mid]==0) ? -1 : 0;

    while (ln_found<30)
    {
      if (wh_l<wh_r)
      {
        var p = data[edge_l];

        edge_l -= 4;
        if (edge_l<0)
          throw("左边缘溢出");

        if (data[edge_l]-p==255)
          ln_found++;

        wh_l += (data[edge_l]==255) ? 1 : -wh_l;
      }
      else
      {
        var p = data[edge_r];

        edge_r += 4;
        if (edge_r>(w-1)*4)
          throw("右边缘溢出");

        if (data[edge_r]-p==255)
          ln_found++;

        wh_r += (data[edge_r]==255) ? 1 : -wh_r;
      }
    }

    // shrink
    while (data[edge_l]==255)
      edge_l+=4;
    while (data[edge_r]==255)
      edge_r-=4;

    var l=edge_l/4, r=edge_r/4, p=l, s=(r-l)/95;
    var bits = new Array(95);

    for (var i=0; i<95; i++)
    {
      var p_l = Math.ceil(p), p_r = Math.floor(p+s);
          c = 0;

      for (var j=p_l; j<=p_r; j++)
        c += (data[j*4]==0)?1:0;
      bits[i] = Math.round(c/(p_r-p_l+1));
      //console.log(p_l+" -> "+p_r+", "+c+"/"+(p_r-p_l+1)+"="+bits[i]);
      ctx.fillStyle = (i%2==0)? "rgba(255,0,0,0.5)" : "rgba(0,255,0,0.5)";
      ctx.fillRect(p_l, h_mid-1, p_r-p_l+1, 3);

      p+=s;
    }

    this.dump(cvs);
    return(bits);
  }

  this.binarize = function (cvs)
  {
    var w = cvs.width, h = cvs.height,
        ctx = cvs.getContext("2d"),
        imgd = ctx.getImageData(0, 0, w, h),
        data = imgd.data,
        px_count = w*h,
        b_count = new Array(256),
        b_convert = new Array(256),
        pr_accel = 0;

    for (var i=0; i<px_count; i++)
        b_count[data[i*4]] = (b_count[data[i*4]]===undefined) ? 1 : b_count[data[i*4]]+1;
    for (var i=0; i<256; i++)
    {
      var pr = (b_count[i]===undefined) ? 0 : b_count[i]/px_count;
      pr_accel += pr;
      b_convert[i] = Math.round(pr_accel*256);
    }
    for (var i=0; i<px_count; i++)
      data[i*4] = data[i*4+1] = data[i*4+2] =
        ((b_convert[data[i*4]]<this.thresold)?0:255);

    ctx.putImageData(imgd, 0, 0);
    this.dump(cvs);
    return(cvs);
  }

  this.discolor = function (cvs)
  {
    var w = cvs.width, h = cvs.height,
        ctx = cvs.getContext("2d"),
        imgd = ctx.getImageData(0, 0, w, h),
        data = imgd.data,
        px_count = w*h;

    for (var i=0; i<px_count; i++)
    {
      var b = Math.round((data[i*4]*299+data[i*4+1]*587+data[i*4+2]*114)/1000);
      data[i*4] = data[i*4+1] = data[i*4+2] = b;
    }

    ctx.putImageData(imgd, 0, 0);
    this.dump(cvs);
    return(cvs);
  }

  this.img2Canvas = function (img)
  {
    var cvs = document.createElement("canvas");
    cvs.width = img.width;
    cvs.height = img.height;
    var ctx = cvs.getContext("2d");
    ctx.drawImage(img, 0, 0);

    this.dump(cvs);
    return(cvs);
  };

  this.dump = function (cvs)
  {
    var c = document.createElement("canvas");
    c.width = cvs.width;
    c.height = cvs.height;
    c.getContext("2d").drawImage(cvs, 0, 0);

    document.body.appendChild(c);
  }
}
	<!DOCTYPE html>
	<html>
	<head>
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
	<script src="ISBN13Parser.js"></script>
	</head>

	<body>
	<input type="file" accept="image/*" onchange="loadAndParse(this);"/>
	<script>
	var parser = new ISBN13Parser();

	function loadAndParse(input)
	{
	console.log(input.value);

	var reader = new window.FileReader();
	reader.onloadend = function(){
	var img = new Image();
	img.src = this.result;
	alert(parser.parseImage(img));
	};

	reader.readAsDataURL(input.files[0]);
	}

	</script>
	</body>
	</html>
	/** ISBN-13 decoder
	* author by galin<cuter44@foxmail.com>
	* free to use if reserve the author info.
	*/

	function ISBN13Parser(){
	this.sResult = null;
	this.iaResult = null;
	this.baResult = null;
	this.thresold = 80;

	this.cb = (function (){
	var a = new Array();

	a[13]=0; a[39]=0; a[114]=0;
	a[25]=1; a[51]=1; a[102]=1;
	a[19]=2; a[27]=2; a[108]=2;
	a[61]=3; a[33]=3; a[ 66]=3;
	a[35]=4; a[29]=4; a[ 92]=4;
	a[49]=5; a[57]=5; a[ 78]=5;
	a[47]=6; a[ 5]=6; a[ 80]=6;
	a[59]=7; a[17]=7; a[ 68]=7;
	a[55]=8; a[ 9]=8; a[ 72]=8;
	a[11]=9; a[23]=9; a[116]=9;

	return(a);
	})();

	this.parseImage = function (img)
	{
	return(
	this.parseCanvas(this.img2Canvas(img))
	);
	}

	this.parseCanvas = function (cvs)
	{
	this.baResult =
	this.parseBits(this.binarize(this.discolor(cvs)));
	this.iaResult = this.decodeBits(this.baResult);

	var sResult = "";
	for (var i=0; i<13; i++)
	sResult = sResult.concat(this.iaResult[i]);
	this.sResult = sResult;

	return(this.sResult);
	}

	this.decodeBits = function (bits)
	{
	var offset = 3,
	decoded = new Array(13);

	for (var i=1; i<=6; i++)
	{
	var b = 0;
	for (var j=0; j<7; j++)
	b = (b<<1)+bits[offset++];
	decoded[i]=this.cb[b];

	//console.log(b.toString(2) + " -> " + decoded[i]);
	}

	offset = 50;
	for (var i=7; i<=12; i++)
	{
	var b = 0;
	for (var j=0; j<7; j++)
	b = (b<<1)+bits[offset++];
	decoded[i]=this.cb[b];

	//console.log(b.toString(2) + " -> " + decoded[i]);
	}

	decoded[0] = 9;

	return(decoded);
	}

	this.parseBits = function (cvs)
	{
	var w = cvs.width,
	h = cvs.height,
	w_mid = Math.floor(w/2),
	h_mid = Math.floor(h/2),
	ctx = cvs.getContext("2d"),
	data = ctx.getImageData(0, h_mid, w, 1).data,
	edge_l, edge_r, wh_l, wh_r, ln_found;

	wh_l = wh_r = 0;
	edge_l = edge_r = w_mid*4;
	ln_found = (data[4*w_mid]==0) ? -1 : 0;

	while (ln_found<30)
	{
	if (wh_l<wh_r)
	{
	var p = data[edge_l];

	edge_l -= 4;
	if (edge_l<0)
	throw("左边缘溢出");

	if (data[edge_l]-p==255)
	ln_found++;

	wh_l += (data[edge_l]==255) ? 1 : -wh_l;
	}
	else
	{
	var p = data[edge_r];

	edge_r += 4;
	if (edge_r>(w-1)*4)
	throw("右边缘溢出");

	if (data[edge_r]-p==255)
	ln_found++;

	wh_r += (data[edge_r]==255) ? 1 : -wh_r;
	}
	}

	// shrink
	while (data[edge_l]==255)
	edge_l+=4;
	while (data[edge_r]==255)
	edge_r-=4;

	var l=edge_l/4, r=edge_r/4, p=l, s=(r-l)/95;
	var bits = new Array(95);

	for (var i=0; i<95; i++)
	{
	var p_l = Math.ceil(p), p_r = Math.floor(p+s);
	c = 0;

	for (var j=p_l; j<=p_r; j++)
	c += (data[j*4]==0)?1:0;
	bits[i] = Math.round(c/(p_r-p_l+1));
	//console.log(p_l+" -> "+p_r+", "+c+"/"+(p_r-p_l+1)+"="+bits[i]);
	ctx.fillStyle = (i%2==0)? "rgba(255,0,0,0.5)" : "rgba(0,255,0,0.5)";
	ctx.fillRect(p_l, h_mid-1, p_r-p_l+1, 3);

	p+=s;
	}

	this.dump(cvs);
	return(bits);
	}

	this.binarize = function (cvs)
	{
	var w = cvs.width, h = cvs.height,
	ctx = cvs.getContext("2d"),
	imgd = ctx.getImageData(0, 0, w, h),
	data = imgd.data,
	px_count = w*h,
	b_count = new Array(256),
	b_convert = new Array(256),
	pr_accel = 0;

	for (var i=0; i<px_count; i++)
	b_count[data[i4]] = (b_count[data[i4]]===undefined) ? 1 : b_count[data[i*4]]+1;
	for (var i=0; i<256; i++)
	{
	var pr = (b_count[i]===undefined) ? 0 : b_count[i]/px_count;
	pr_accel += pr;
	b_convert[i] = Math.round(pr_accel*256);
	}
	for (var i=0; i<px_count; i++)
	data[i4] = data[i4+1] = data[i*4+2] =
	((b_convert[data[i*4]]<this.thresold)?0:255);

	ctx.putImageData(imgd, 0, 0);
	this.dump(cvs);
	return(cvs);
	}

	this.discolor = function (cvs)
	{
	var w = cvs.width, h = cvs.height,
	ctx = cvs.getContext("2d"),
	imgd = ctx.getImageData(0, 0, w, h),
	data = imgd.data,
	px_count = w*h;

	for (var i=0; i<px_count; i++)
	{
	var b = Math.round((data[i4]299+data[i4+1]587+data[i4+2]114)/1000);
	data[i4] = data[i4+1] = data[i*4+2] = b;
	}

	ctx.putImageData(imgd, 0, 0);
	this.dump(cvs);
	return(cvs);
	}

	this.img2Canvas = function (img)
	{
	var cvs = document.createElement("canvas");
	cvs.width = img.width;
	cvs.height = img.height;
	var ctx = cvs.getContext("2d");
	ctx.drawImage(img, 0, 0);

	this.dump(cvs);
	return(cvs);
	};

	this.dump = function (cvs)
	{
	var c = document.createElement("canvas");
	c.width = cvs.width;
	c.height = cvs.height;
	c.getContext("2d").drawImage(cvs, 0, 0);

	document.body.appendChild(c);
	}
	}