function drawImage(imageObj) {
        var canvas = document.getElementById('myCanvas');
        var context = canvas.getContext('2d');
        var imageX = 10;
        var imageY = 6;
        imageWidth = imageObj.width;
        imageHeight = imageObj.height;

        context.drawImage(imageObj, imageX, imageY);

        var imageData = context.getImageData(imageX, imageY, imageWidth, imageHeight);
        data = imageData.data;
        console.log(imageData);

        // iterate over all pixels
        for(var i = 0, n = data.length; i < n; i += 4) {
        console.log("long du tableau : "+data.length);
          var red = data[i];
          var green = data[i + 1];
          var blue = data[i + 2];
          var alpha = data[i + 3];
            console.log(data[10]);
        }
          
        // iterate over all pixels based on x and y coordinates
        for(var y = 0; y < imageHeight; y++) {
    
          // loop through each column
          for(var x = 0; x < imageWidth; x++) {
              
            var red = data[((imageWidth * y) + x) * 4];
            var green = data[((imageWidth * y) + x) * 4 + 1];
            var blue = data[((imageWidth * y) + x) * 4 + 2];
            var alpha = data[((imageWidth * y) + x) * 4 + 3];
            console.log('rangée '+y+', colonne '+x+': RGBA = ('+red+','+green+','+blue+','+alpha+')');
          }
        }
      }