Are you opposed to self hosting?
...I don't even know what that means!....
I use photobucket, you just upload the picture, then when you have it uploaded there is a share tab when you mouse over the picture. Click that and it gives you the URL, then on here you can click that picture that looks like a mountain view and paste the URL in.
I'll try that.
This way you can post any size picture you want. Speaking of size, you may have to resize the picture. We've all seen those giant ones some people post.
It was definitely my wife's camera. I had no problem posting a picture using my Droid.