You can insert attached images into comments. It's in the menu of the "Visual" editing pane, or doable by inserting some magic [] or {} incantation in the "Text" pane. Sorry, I don't know it by heart. But you can do it visually first, then find and learn it by switching to the textual view. I do remember you can specify size by optional width and height parameters; without them, I think you get just a tiny thumbnail.