A media transport system is used to transport a media sheet along a media transport path past an image capture system. The image capture system includes an image capture device positioned to capture an image of the media sheet, and a platen positioned behind the media sheet, wherein a surface of the platen includes a non-uniform density pattern. The image capture system captures an image of the media sheet that includes at least one edge of the media sheet and a portion of the platen that extends beyond the edge of the media sheet. An image analysis system automatically analyzes the captured digital image to detect an edge position of the media sheet by detecting a platen region that includes the non-uniform density pattern and a media region. The detected edge position is used to adjust a position that a printing module prints image data onto the media sheet.