I guess that is my question. I am unsure as to what you mean by a viewable url.
You said viewable image. I misplaced the word viewable in my response.
Nevermind that. Point is, when you post an image, you post a URL and click the button that tags it as an image (the one that looks like the Mona Lisa below Bold). It then shows up in the post as an image. Fine.
If you don't like something about the post layout, and you go back to click modify, you get a post that doesn't have any code in it. You have how the code was implemented. So then you click the last button on the second row that has the red brackets with the pointer to see all the code... except you (or in this case I) don't. Everything you (I) did when you clicked the Mona Lisa is gone. When you (I) click preview it's gone. Bold code shows up fine, font sizes, font colors codes etc shows up fine float left and float right codes show up fine.
[img padding=10 width=300]hypothetical-img.url[/img]
does not show up on the modify/reply window at all.
if you didn't change any padding or width and just left it with
it still disappears.
If you save it without the image encoding, you lose the images.