How to zoom in and out in WPF

Question

Hello,
Sorry if I am on the wrong page, but I have a question regarding WPF and how to zoom in and out, how do you accomplish this. What i want to make is for somone to browse for an image and select it, then comes up on the program and it is shown on the imageviewer( which i have done this) now for the question, how do I get it to enhance the image on a particular side, for example, i want the user to be able to draw a rectangular part on the picture and able to click on the button to zoom in on that recangular part and zoom back out, how can this be done?
Thank you