I use XnView.
The problem is very little. Only when ImageShack doesn't works fine and, at the same time, the sistem of IMCDB must to decrease the pic until 720X.... or ....X480 maximum.

Only pics in HD can be biggers than 720x.

Small XnView tutorial made previously on another topic

http://forum.imcdb.org/forum_topic-1201-How_you_can_submit_pictures.html