Solution
Neither the OptraImage nor the MarkNet N2601e can rotate the image due to lack of internal (MFP) memory. Accordingly, with TIFF and JPEG, the image will always appear in portrait orientation even if landscape orientation is chosen.
However, when a landscape PDF or PostScript image is scanned, code in the file header tells the viewer to rotate the image to landscape when displayed. The X7500, X4500, 5500, and all other Enhanced Multifunction Devices have more than enough internal memory to rotate the image.
NOTE: This issue arises with both the ScanBack utility and the Scan Profile option on the Web page.