Sony DCR-TRV39 - Manual (Page 32)

Vertically oriented pictures are usually saved horizontally, though Exif files will contain information to the effect
that the picture was taken vertically. ImageMixer creates vertical thumbnails for those files in accordance with the
Exif information, even though they may have originally been saved as horizontal images.
Copyright © 2001-2002 PIXELA Corp. All rights reserved.