How to resize/exclude images RSS feed from forum to blog

[SelfSufficientMe]

I setup my blog to grab the RSS feed from my forum and that works fine when there is no image in the post; however, when an image is included it gets displayed on my blog as full size which is obviously not ideal (especially when the feed is displayed in a sidebar). I have removed the RSS feed for now.

Does anyone have any advice as to how I can exclude or resize images to a thumb in the RSS feed from my forum so it displays on my blog correctly?

Thanks