Avision IS15 (FS-0913B) - Manual (Page 14)

3.4 Scan dark or night pictures
When you need to scan dark or night pictures, be sure to insert your photo into
the white plastic sheath to avoid an incomplete scanned image. However, using
the white plastic sheath will disable the auto crop (automatic crop your image
according to your photo size) and deskew (auto straighten) functions. This
means though you have completed scanning your photo, your image may look
slightly skew if you have not placed the photo straight in the scanner.
.
The scanned image using white plastic sheath
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