Serrated image when using class.upload.php

Question

I’m using the class class.upload.php to upload the images.

I inform you of the quality I desire $handle->jpeg_quality = 75;, but still the image is getting serrated. Link: https://github.com/verot/class.upload.php

Someone can help me?

if (!empty($_FILES['avariaFoto']['name'])) {
  $files = array();
  foreach($_FILES['avariaFoto'] as $k => $l) {
    foreach($l as $i => $v) {
      if (!array_key_exists($i, $files)) $files[$i] = array();
      $files[$i][$k] = $v;
    }
  }
  foreach($files as $file) {
    $handle = new upload($file);
    if ($handle->uploaded) {
      $handle->file_new_name_body = date('dmYhis');
      $handle->image_resize = true;
      $handle->image_x = 800;
      $handle->image_ratio_y = true;
      $handle->jpeg_quality = 75;
      $handle->image_convert = 'jpg';
      $handle->file_overwrite = false;
      $handle->file_auto_rename = true;
      $handle->mime_check = true;
      $handle->Process('imagens/');
      $foto = $handle->file_dst_name;

      if ($handle->processed) {
        $handle->clean();
      } else {
        echo '  Erro: '.$handle - > error.
        '';
      }
    }
  }
}