I made a shortcode to embed images that I upload through the files and images tab. In my template, I would like to be able to resize this image but I can not really see how to do that. I've done it before using $SetWidth, ResizedImage, etc, with images in custom page types but it does not seem to work with the URL to the image I generate with my shortcode pardser. is that because it is an "image object" when it is a page type? I hope I am making sense here, I'm on the edge of my SilverStripe knowledge coding in the dark :0)
Basically I want to use a resize function on the source for an image tag, hopefully saving and caching the resized image like it seems to do in SS. How can I do that?