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I am scanning old family photos and hand-written letters. Quite often there is information at the very edges of the object. It is therefore important that the image captures the whole object, not losing even a millimeter on any side. It's also very desirable to have the object aligned to the vertical/horizontal sides of the image, at least when when the object is rectangular.

Of course, I quickly discovered a well-known effect that my scanner (of a 2017 Canon PIXMA MFP for 120 euros) doesn't scan the full area of the glass plate, and crops 2-3 mm at all edges.

I've tried putting original further away from the edges and straightening them in software. So far, I couldn't get the same quality as without straightening: for photos it works OK, but sharp ink lines in hand written text get slightly blurred, the ink line structure is lost. Since I am doing this for digital preservation purposes, I would like to avoid it.

I also tried using a narrow paper stripe at the edge of the glass plate as an alignment guide and spacer, but it's edge roughness is visible in the scans and annoys me. Also, it's roughness means I don't want to slide an old photo against it, to prevent damage.

My MFP printer is now broken, I will buy a new one and I would like to address this problem. I am happy to pay more to solve it. To my dismay, I cannot find any scanner or MFP so far which manual wouldn't mention the same effect. Even Epson V850, which is, alone, seven times the price of my MFP, seems to have it. (User manual says "If the edges of a scanned image are cropped, make sure your original is placed correctly for scanning. If necessary, move your original away from the edges of the scanner glass slightly.")

I wonder what is the reason why it is so ubiquitous (I am an optical engineer and of course my brain is full of possible solutions), if anyone can recommend a scanner that wouldn't suffer from it, or a method to improve my experience despite this cropping.

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  • \$\begingroup\$ I believe the misalignment is caused by the scanner construction. Its a box with a bottom and and a top, the scanner head moves on rails attached to the bottom but the glass and its fame are attached to the top. And top and bottom are both pieces of plastic attached with screws so they can be misaligned. My scanner (Epson V200) isn't even "true", it scans very slightly in diagonal.... \$\endgroup\$
    – xenoid
    Oct 7, 2022 at 22:28
  • \$\begingroup\$ ... You will also discover that the scanner has a transversal distortion: scan the same photo twice, one scan with a 180° rotation. Load both in Gimp/Photoshop, rotate one by 180°, align them and put the top on in difference mode to check proper overlap, you will likely never achieve this. You can also scan a CD/DVD, and check in your image editor if you get a circle. \$\endgroup\$
    – xenoid
    Oct 7, 2022 at 22:30
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    \$\begingroup\$ @xenoid, sure but what prevents the manufacturers from making the scanner detector a couple millimetres wider and calibrating scanning to mechanics, similarly to how the inkjet heads are calibrated? \$\endgroup\$
    – texnic
    Oct 8, 2022 at 12:01
  • \$\begingroup\$ @texnic Cost. Everything is about cost. \$\endgroup\$
    – osullic
    Oct 12, 2022 at 9:06
  • \$\begingroup\$ What, by the way, is a MFP? \$\endgroup\$
    – osullic
    Oct 12, 2022 at 9:09

3 Answers 3

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I may be completely misunderstanding the issue but…..

Perhaps just mounting each item to be scanned on a backing paper that is larger than the item. I’ve done this using quadrille-ruled paper as backing that facilitates aligning the item to be scanned on the backing. Then finding and setting the best position for the quadrille-ruled sheet for best scanning.

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  • \$\begingroup\$ It seems you understand the question correctly, and this method probably works. However, when I need to scan 100 objects, double-sided, it's a significant overhead. I would prefer to buy a scanner that just does what is expected. Also, in genealogy, one best practice is never to perform any manipulations on the originals that may impact their condition, mechanically or chemically. How to you fix your originals to the backing paper? \$\endgroup\$
    – texnic
    Oct 12, 2022 at 6:42
  • \$\begingroup\$ @texnic an alternative would be to cut a border out of some slightly stiffer than paper sheeting (whether cardboard or plastic or ...) that the photos would then fit in... You could even do just the top and left edges if the photos are different sizes - just something to get the spacing between the glass edge and the photo right while helping keep alignment correct... \$\endgroup\$
    – twalberg
    Oct 12, 2022 at 14:42
  • \$\begingroup\$ A new scanner is significant overhead. Quadrille-ruled paper is ~$4 for 100 sheets while very low stick purple painters’ tape is about the same at a hardware store. This tape will stabilize well enough and will peel from fragile surfaces quite well . I’ve done exactly this to affix old clippings to temporary support. \$\endgroup\$ Oct 13, 2022 at 14:52
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I hate to say it but maybe the answer is simply to lower your standards. Use something better than a scrap of paper as your guide to shift the to-be-scanned item further into the scanner platen. Don't press the to-be-scanned item right up to your guide. Either accept the fractions of a degree off-centre that it will be, or use software to rotate and just accept the result. Very often, tasks such as yours fall to "analysts" who focus too much on exacting accuracy of irrelevant details. You are not trying to produce counterfeit banknotes here - you are just archiving personal documents and photos, so that they can be seen/read/appreciated by others.

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Have you thought about using a camera and 2 side lights, a tripod and a sheet of glass to weigh the paper down instead of a scanner? It might be faster, although it will be taking some time to build a good setup.

If you are going high volume, this will be definitely faster than a flatbed scanner, plus it will cope with any unusual format of paper.

See here: Photographing Older Documents

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