how to get the width and height of a loaded image ?

Much better demesstified Thanks, Zaxist.

brands = {};

byLetter = {'A':0,'B':0,'C':0,'D':0,'E':0,'F':0,'G':0,'H':0,'I':0,'J':0,'K':0,'L':0,'M':0,

            'N':0,'O':0,'P':0,'Q':0,'R':0,'S':0,'T':0,'U':0,'V':0,'W':0,'X':0,'Y':0,'Z':0};

//------------------------------------------------------

$.getJSON( 'brands.json', function(data)

{

  // the JSON file contains objects sorted by alphabetical order of their brand property

  brands = data;

  // initialize the array of entries by letter

  var key = 'z';

  $.each( data, function( index, entry)

  {

    var initial = entry.brand.charAt(0);

    if (initial != key && initial !='É')

    {

      byLetter[ initial] = index;

      key = initial;

    }

  });

  // fill empty entries

  for (var keyLetter in byLetter)

  {

    if (byLetter[ keyLetter] == 0 && keyLetter != 'A')

    {

      if (keyLetter == 'Z')

      {

        byLetter[ 'Z'] = byLetter[ 'Y'];

      } else {

        // next entry value

        byLetter[ keyLetter] = byLetter[ String.fromCharCode( keyLetter.charCodeAt() +1)];

      }

    }

  }

  swapLogos( 0);

});

//------------------------------------------------------

function swapLogos( iFirst)

{

console.log( iFirst);

  for( var i = 0; i < 15; ++i)

  {

    var theLogo = sym.getSymbol( "cell_" +(i +1)).$('square');

    var iBrand =  iFirst +i;

    if (iBrand < brands.length)

    {

      theLogo

        .css(

        {

          "background-image":"url(images/" +brands[ iBrand].logo +".gif)",

          "background-size":"auto",

          "background-repeat":"no-repeat",

          "background-position":"center"

        })

        .show();

    } else {

      theLogo.hide();   

    }

  }

}

//------------------------------------------------------

$('.lettre').on('click', function()

{

  var letter = $( this).attr( 'ID').charAt( 6);  // Stage_A

  swapLogos( byLetter[ letter]);

  // update highlighted letter (color)

  $('.lettre').css( 'color', '#EEE');

  $(this).css( 'color', '#FF3');

});

//------------------------------------------------------

Dowloadable here : https://app.box.com/s/c1hlvbfrum4yzypc1mid

Gil