Figure out ofImage dimensions when using ofxGameCamera

I’m using some ofImages in my scene, I can move them around and then visualize it using ofxGameCamera. My ofImages actual size is 1920 x 1080. Using ofxGameCamera I can zoom in and out. I’d like to calculate the ofImage’s rectangle dimensions based on the current view.
Or which is the same, the screen pixel size of the image frames in the view while moving with ofxGameCamera. How could I do that?