It is a well known fact that shooting a gun in a confined space produces a much louder noise as the sound bounces off the walls. You can read a discussion of it here.
Well, look at how confined this space is: it was in this cubby-hole that the shot was taken.
So, the sound of the blast should have been startling and perhaps even painful. Remember that even in the great outdoors, people wear ear protection when they shoot guns. Here is an article which states that the Colt Detective Special "sure is loud."
But, nobody in the footage of the Oswald shooting shows any reaction to the sound of the blast. Nobody jumps or acts startled.
And, I know that the reason the Jackson photo was given the look that it has is because a contact shot would cause so much damage, including from the muzzle flash which is burning hot gases, that they had to cover up the whole area to explain why we don't see any damage at all- to Oswald or his clothing.
With arms akimbo, they conveniently got everything covered up so that no damage had to be shown. But in reality, there was no damage. Oswald was NOT shot in that garage. The garage shooting was a ruse. And, the guy pretending to shoot Lee Oswald was NOT Jack Ruby. Hey, it's hard enough to explain why Jack Ruby would shoot Oswald at all, but it is an impossible task to explain why he would PRETEND to shoot him.