This question may not be well describe, but I will try to explain as best as possible.
Suppose somebody gives me some image (say of a plot on the complex plane), and also describes the dimensions of it, say the boundary of the picture vertically is from the origin to the point $2i$ and horizontally from $-1$ to $1$.
Now suppose I want to add some graphic elements such as a line or a Bezier curve using Mathematica. Is there some way to tell Mathematica the scale of the image so that the defining points of graphic elements are consistent with the coordinates of image?
(Apologies if this has an obvious solution, I am currently running a large piece of code so I cannot experiment with this, but I think in past experience this is not an obvious thing one is able to do.)