Changing the default category image.

Current category images default to: barcode.png
Is it possible to change the default?
Is it possible to set the default to no image?

One workaround is to add something like the following to the template listing_img_title.php file:

The default image can be changed in the configuration under the tab files.
You can also change the item layout to "title" instead of "image and title" so that category images won't be displayed.

Thanks re default image I was looking in the wrong.