Quicktabs Image in tab title
Probably best to add your own Quicktabs style and use CSS background images.

In a custom module

function MYMODULE_quicktabs_tabstyles() {
  $tabstyles_directory = drupal_get_path('theme', 'MYTHEME') . '/quicktabs';
  $files = file_scan_directory($tabstyles_directory, '/\.css$/');
  $tabstyles = array();
  foreach ($files as $file) {
    // Skip RTL files.
    if (!strpos($file-&gt;name, '-rtl')) {
      $tabstyles[$file-&gt;uri] = drupal_ucfirst($file-&gt;name);
    }
  }
  return $tabstyles;
}


CSS files in THEMEDIR/quicktabs/*.css will be read as a potential style

In your theme dir, add /quicktabs/image-tabs.css 

Clear all caches

New style should be available, with accompanying CSS classes, add to your new CSS file.

Alternatively target the existing quicktabs classes with CSS.

Basic CSS background image tute here