deep zoom image size issue

Question

Hello everyone,

My question is from the below MSDN link about deep zoom,

1. When ViewportWidth is 1, it means the picture is never zoomed in and never zoomed out, and displayed at its original size (original size I mean the width and height defined in picture header), correct? 2. My confusion is, when we use deep zoom composer, the total size of input images should be very large, but the output size of composed picture is not very large (e.g. we can select output size to be 800 * 600). So, I doubt whether when ViewportWidth is 1, it means the picture is displayed at its original size (original size I mean the width and height defined in picture header), if not, how much size the picture is displayed when ViewportWidth is 1?

http://msdn.microsoft.com/en-us/library/system.windows.controls.multiscaleimage.viewportorigin(VS.95).aspx

thanks in advance, George