Its called a picture within a picture
The term is inset.
A picture that has a smaller copy of itself within the picture, with the copy having an even smaller copy, that continues to (theoretically) infinity, is called a Droste Effect or recursive picture.
That's an "inset".
1. Droste effect2. mise en abyme
The correct phrase is "I can see in this picture," as it refers to looking inside or within the picture itself.
picture graph
Is called a glyph.
A caption.
Inset.
dog
It is called an Avi (avatar) or DP (display picture.)
The area in the background of a picture is called the background or backdrop.
A thumbnail picture
That is a picture that has 1 mega bite of space within itself.