Horizontal stripes may be caused by the reflection of fluorescent or other lighting. It can be reduced by choosing "reducing fluorescent lamp flicker" scanning mode.
In the ScanSnap setup dialog box, select the [Scanning] tab, and click the [Option] button.
The [Scanning mode option] dialog box appears. Click the [Image quality] tab, and select the [Reduce fluorescent lamp flicker] check box.
For more detail, refer to "Reducing the Effect of Lighting (For SV600)" in the [Scan Setting for Your Intended Use] on ScanSnap Advanced Operation Guide.