Plugin lightbox su tag img class

Salve a tutti.

Ho un plugin per joomla che automaticamente, al click, apre tutte le immagini presenti negli articoli con una light box.
Siccome ho già molti articoli con numerose immagini per cui ho impostato già una lightbox "manuale" con cui il plugin va in conflito, volevo utilizzare il plugin soltanto per i futuri articoli.
Il plugin agisce sul tag <img>.
Mi permetto di postare il codice in quanto sono soltanto poche righe.
Vorrei sapere se è possibile modificarlo in qualche punto in modo che sia valido soltanto per le immagini a cui attribuisco una classe specifica

<?php
 * @license   http://www.gnu.org/licenses/gpl-3.0.html
 */

// no direct access
defined('_JEXEC') or die;

jimport('joomla.plugin.plugin');

class plgContentJhimagepopup extends JPlugin
{
    public function plgContentJhimagepopup(&$subject, $params)
    {
        parent::__construct($subject, $params);
    }

    public function onContentPrepare($context, &$article, &$params, $page = 0)
    {
        if ($context == 'com_finder.indexer')
        {
            return true;
        }

        JHtml::_('jquery.framework');
        JHtml::_('bootstrap.framework');

        switch ($this->params->get('popup_technology', 0))
        {
            case '1':
                /* Joomla MooTools SqueezeBox */
                
                JHTML::_('behavior.modal');

                $regex      = '/<img.*?>/';

                $createImageLink = function($imageTag)
                { 
                    preg_match('/src="([^"]*)"/i', $imageTag[0], $results);
                    $srcAttribute = $results[0];
                    $srcUrl = explode("=", $srcAttribute);
                    return '<a href=' . $srcUrl[1] . ' class="modal">'.$imageTag[0].'</a>';
                };                                                     

                if (isset($article->text))
                {
                    $article->text = preg_replace_callback($regex, $createImageLink, $article->text);
                }
                if (isset($article->introtext))
                {
                    $article->introtext = preg_replace_callback($regex, $createImageLink, $article->introtext);
                }
                break;

            case '2':
                /* Colorbox */
                
                $doc =& JFactory::getDocument();
                $doc->addScript('//cdnjs.cloudflare.com/ajax/libs/jquery.colorbox/1.4.33/jquery.colorbox-min.js');
                $doc->addStyleSheet('//cdnjs.cloudflare.com/ajax/libs/jquery.colorbox/1.4.33/example1/colorbox.min.css');

                $regex      = '/<img.*?>/';

                $createImageLink = function($imageTag)
                { 
                    preg_match('/src="([^"]*)"/i', $imageTag[0], $results);
                    $srcAttribute = $results[0];
                    $srcUrl = explode("=", $srcAttribute);
                    return '<a href=' . $srcUrl[1] . ' class="jh-image-popup-colorbox">'.$imageTag[0].'</a>';
                };                                                     

                if (isset($article->text))
                {
                    $article->text = preg_replace_callback($regex, $createImageLink, $article->text);
                    $article->text .= '<script> jQuery( document ).ready(function() { jQuery(".jh-image-popup-colorbox").colorbox(); });</script>';
                }
                if (isset($article->text))
                {
                    $article->introtext = preg_replace_callback($regex, $createImageLink, $article->introtext);
                    $article->introtext .= '<script> jQuery( document ).ready(function() { jQuery(".jh-image-popup-colorbox").colorbox(); });</script>';
                }
                break;

            case '3':
                /* lightbox2 */
                
                $doc =& JFactory::getDocument();
                $doc->addScript('//cdnjs.cloudflare.com/ajax/libs/lightbox2/2.7.1/js/lightbox.min.js');
                $doc->addStyleSheet('//cdnjs.cloudflare.com/ajax/libs/lightbox2/2.7.1/css/lightbox.css');

                $regex      = '/<img.*?>/';

                $createImageLink = function($imageTag) { 
                    preg_match('/src="([^"]*)"/i', $imageTag[0], $results);
                    $srcAttribute = $results[0];
                    $srcUrl = explode("=", $srcAttribute);
                    return '<a href=' . $srcUrl[1] . ' data-lightbox="jh-image-popup">'.$imageTag[0].'</a>';
                };                                                     

                if (isset($article->text))
                {
                    $article->text = preg_replace_callback($regex, $createImageLink, $article->text);
                }
                if (isset($article->text)) {
                    $article->introtext = preg_replace_callback($regex, $createImageLink, $article->introtext);
                }
                break;

            case '4':
                /* Magnific Popup */
                
                $doc =& JFactory::getDocument();
                $doc->addScript('//cdnjs.cloudflare.com/ajax/libs/magnific-popup.js/1.0.0/jquery.magnific-popup.min.js');
                $doc->addStyleSheet('//cdnjs.cloudflare.com/ajax/libs/magnific-popup.js/1.0.0/magnific-popup.min.css');

                $regex      = '/<img.*?>/';

                $createImageLink = function($imageTag)
                { 
                    preg_match('/src="([^"]*)"/i', $imageTag[0], $results);
                    $srcAttribute = $results[0];
                    $srcUrl = explode("=", $srcAttribute);
                    return '<a href=' . $srcUrl[1] . ' class="magnific_popup">'.$imageTag[0].'</a>';
                };                                                     

                if (isset($article->text))
                {
                    $article->text = preg_replace_callback($regex, $createImageLink, $article->text);
                    $article->text .= '<script> jQuery( document ).ready(function() { jQuery(".magnific_popup").magnificPopup({ type: "image", enableEscapeKey:true }); });</script>';
                }
                if (isset($article->text))
                {
                    $article->introtext = preg_replace_callback($regex, $createImageLink, $article->introtext);
                    $article->introtext .= '<script> jQuery( document ).ready(function() { jQuery(".magnific_popup").magnificPopup({ type: "image", enableEscapeKey:true }); });</script>';
                }
                break;

            case '5':
                /* Swipebox */
                
                $doc =& JFactory::getDocument();
                $doc->addScript('//cdnjs.cloudflare.com/ajax/libs/jquery.swipebox/1.3.0.2/js/jquery.swipebox.min.js');
                $doc->addStyleSheet('//cdnjs.cloudflare.com/ajax/libs/jquery.swipebox/1.3.0.2/css/swipebox.min.css');

                $regex      = '/<img.*?>/';

                $createImageLink = function($imageTag)
                { 
                    preg_match('/src="([^"]*)"/i', $imageTag[0], $results);
                    $srcAttribute = $results[0];
                    $srcUrl = explode("=", $srcAttribute);
                    return '<a href=' . $srcUrl[1] . ' class="jh-image-popup-swipebox">'.$imageTag[0].'</a>';
                };                                                     

                if (isset($article->text))
                {
                    $article->text = preg_replace_callback($regex, $createImageLink, $article->text);
                    $article->text .= '<script> jQuery( document ).ready(function() { jQuery( ".jh-image-popup-swipebox" ).swipebox(); });</script>';
                }
                if (isset($article->text))
                {
                    $article->introtext = preg_replace_callback($regex, $createImageLink, $article->introtext);
                    $article->introtext .= '<script> jQuery( document ).ready(function() { jQuery( ".jh-image-popup-swipebox" ).swipebox(); });</script>';
                }
                break;
        }
        return true;
    }
}

Poichè il tag <img> viene richiamato con $regex = '/<img.*?>/'; nei 5 casi di lightbox disponibili, volevo capire se era possibile agire sulla regex perchè accetti soltanto le immagini con una classe specifica oppure se bisogna agire su qualche altra regola.
Grazie