How can i set a class on the images i generate with my extension

If you're generating images with your extension and you need to add a custom class on these images like (<img class="yourclass" src="yourfile">), then you can achieve this with the following snippet. Pay attention to the 6th line!

$conf['image.']['file'] = 'uploads/tx_yourextension/' . $row['image'];
$conf['image.']['file.']['maxW'] = $this->conf['imageMaxWidth'];
$conf['image.']['file.']['maxH'] = $this->conf['imageMaxHeight'];
$conf['image.']['altText'] = $row['title'];
$conf['image.']['titleText'] = $row['title'];
$conf['image.']['params'] = 'class="yourclass"';
$imgCode = $this->IMAGE($conf['image.']);