[TYPO3-english] how to: display an image generated on the fly without writing it to disc - from a typo3 v4.5 extbase

[Calgacus map Brude]

Hi,
I am generating barcode images (using PHP-Barcode 0.4 http://www.ashberg.de/php-barcode/) with imagepgn but would rather not save them to disc - just seems unnecessary as the images aren't needed for long and they are small and quick to generate when needed.

I was thinking of an action showbarcodeAction that would just call the imagepgn function but there needs to be a template associated with the action right?  And if so won't it produce some html when all I really need is the image?   can I show the image in a standard img tag even though it is not actually saved to disc?

I am using typo3 v4.5 with extbase.  

Thanks!