I have many photos loaded into my unit. In landscape orientation, all display sized to fit on the screen with no cropping -- i.e., they are letterboxed as needed to fit the entire image on the screen. However, in portrait orientation, some images are displayed scaled up a bit to fill the screen. In order to see the entire image, I must "pinch down." Is this normal behavior? If so, is there some method to change the default behavior, so that in portrait orientation images are always scaled to fit entirely on the screen?