The point of the top-left corner of the rectangular area of the image to be displayed. The coordinates of the point are in local coordinates (0-1) relative to the displayed image. For example, a ViewportOrigin point value of 1,1 would specify an origin on the lower right-hand corner of the image. Because this origin is for the top-left corner of the rectangular area of the image displayed, a value of 1, 1 would actually show nothing of the image (area would be lower and to the right of the image). As another example, a point at 0.5, 0.5 would be directly in the center of the image and therefore the area shown would be to the lower-right of the image center.
