I have noticed that some people seem to be able to post pictures to the forum that show up without scroll bars whereas other postings do have scroll bars. Nobody has been able to give me an answer yet as to why or how to avoid the scroll bars. Usually pictures show up on screen with a limited width (they get scaled), but I seem to recall even seeing some pictures that were extra-wide without any horizontal scroll bar.
An interesting point about the pictures with no scroll bar is that when you move the mouse over the picture, the icon changes to a pointing hand: the picture can be clicked on to give you a magnified display. Pictures without scroll bars don't have that property; when you mouse over them the pointer remains an arrow and clicking on the picture does remove the scroll bars but does not open up a new window with a magnified display.
Sometimes even the very same user has pictures in each category, e.g. viewtopic.php?f=70&t=3948&p=26162#p26211
AlexC's pictures without the scroll bar are 800 X 600. So herewith I try three copies of one of my pictures using the same ratio, at 400 X 300, 800 X 600, and 1600 X 1200
Egads! In my preview screen the 1600 X 1200 picture has no scroll bars and is live! The more I investigate this the more I don't understand it!