How to test a login function with a dynamic generated verification number?

Dear all,

Now I need to test a login case. It has user name, password and verification number inputbox. Everytime you refreash the web, the verification number will be generated dynamicly. You need to catch this number and text it to the inputbox, then you can login sucessfully. How can I get that dynamic number (the generated number is a picture)?

Many thanks

Ian

Get the image and response that for user to react,I think.