Cropping during batch scanning
Rereading your answer to the scanner question (Ask AP, AP 18 January) has prompted me to ask a further question. I have an Epson Perfection V700 and a Plustek OpticFilm 8200i Ai that together cover my general scanning requirements, but I now have a lot of family history photographs that I would like to scan, including 300 mounted 35mm transparencies. When I try to batch-scan these using the V700 (using the supplied film holder and Epson Scan’s ‘professional’ mode), the frames are cropped heavily, to about 32x21mm.
I am using the Epson Scan option because the SilverFast software that came with the scanner won’t work on my current 64-bit machines. I have been considering upgrading to SilverFast Ai Studio 8 for the V700, but before making that investment can you tell me if there is any known history of cropping by the V700? Also, is there a work-around for this issue? - Hamilton Smith
We would be perhaps more surprised if you had told me the scanner didn’t crop your images. The fact is, using a film holder in a flatbed scanner is always going to be an imprecise exercise. For a start, the film holder is not held in the exact same position every time you put it in your V700. The design means that it can move slightly, so it may be a little more to the left when you do your first batch of scans and a little to the right when you scan your next batch.
Similarly, your film is never going to be in the same position when you put it in the holder. Mounts vary in size slightly and this is enough to allow the mount to move around in the holder. There is also the actual aperture in the mount itself: not all 35mm slide mounts have identical windows for your film. So, with all these variables, there’s no guarantee that your film is going to be in the same place every time you load your scanner and that’s where the problem lies.
If you’re manually setting your own crop area for a scan it isn’t an issue, but for automated batch scanning it’s up to the software to identify your frame(s). There are generally two approaches to frame selection. The first, which is used by SilverFast, is for the software to attempt to determine the edges of each frame automatically. This ‘intelligent’ system can work to an extent, but it takes time. It also requires contrast at the frame’s edge: a dark image in a dark mount isn’t going to be identifed with accuracy, if at all, resulting in manual intervention being needed.
The alternative (as used by Epson Scan) is to program the software to scan a fixed area in a fixed position, based on where the film holder/film is (roughly) designed to sit. The advantage of this system is that it won’t be thrown by the content of the frame, and there’s no processing time required. The problem is that your film doesn’t sit in the same place every time, so if the scanner was set to digitise a 36x24mm ‘full-frame’ area, it would almost certainly mean that you end up with one or two edges of the mount being included in your scans. To prevent this from happening, the target area for the scan is reduced. As a result, you lose some of the image during the scanning process, but at the same time you don’t have to then go through your scans and manually crop out any extraneous edges, or manually select the scan area to start with.
Unfortunately, if you want to make your batch scanning as automated a process as possible, you have to accept that there are limitations. Either you stick with Epson Scan and accept the cropping, or you upgrade to SilverFast and spend a little longer waiting for its frame-detection algorithms to work and stepping in when they struggle. The third option is to use Epson Scan, but make individual frame selections. Again, this will take longer, but you will be guaranteed to get ‘full-frame’ scans, without the expense of upgrading any software.