The width of the area of the image displayed. This value is in logical coordinates. For example a value of 1 displays the entire image (no zoom), a value of 0.5 is 200% zoomed in and a value of 0 is completely zoomed (user cannot see the image at all). A value above 1 is zooming out from the image. For example, a value of 2 means that the image will take up half the size of the System.Windows.Controls.MultiScaleImage control area (50% zoom).