DPI change

[rafik73github]

Welcome Is it possible to change the DPI for JPG? For now I have to deal in the following way, but it slows down work, because the image must be sent to the server to change DPI in PHP.

JS:

var pdf = $('#pdf_area > .ol-viewport')[0];

domtoimage.toJpeg(pdf,
 { 
 quality : 1
 }
 )
  .then(function (dataUrl) {

     // alert(dataUrl);
      //########################################################

    $.ajax({            // ajax
    type     : "POST",
    url      : "dpi_change.php",
    data     : {
              ajax_dataUrl : dataUrl,
              ajax_pdf_zoom_terrain_number : pdf_zoom_terrain_number
               }
    ,
     context: this,

    success : function(callback) { 

    var link = document.createElement('a');
        link.download = 'Teren_numer_' + pdf_zoom_terrain_number +'.jpg';
        link.href = callback;
        link.click();

                            }  //success

               });     //ajax     

PHP:

$ajax_dataUrl = isset($_POST['ajax_dataUrl']) ? $_POST['ajax_dataUrl'] : '';
$ajax_pdf_zoom_terrain_number = isset($_POST['ajax_pdf_zoom_terrain_number']) ? $_POST['ajax_pdf_zoom_terrain_number'] : '';

$path = $ajax_dataUrl;

$del_string = 'data:image/jpeg;base64,';
$path = str_replace($del_string, "", $path);
$path = base64_decode($path);
$image = substr_replace($path, pack("cnn", 1, 180, 180), 13, 5);

$enc = base64_encode($image);
$callback = $del_string.$enc;
echo $callback;