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.
Inset.
dog
picture graph
Is called a glyph.
A caption.
That is a picture that has 1 mega bite of space within itself.
It is called an Avi (avatar) or DP (display picture.)
A thumbnail picture
This picture is called "pictogram".