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Scanning with Xiaomi Mi 9 but bad(bend) results, what camera can I use?

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bensan
Posts: 1
Joined: 20 Nov 2021, 00:17
Number of books owned: 100
Country: México

Scanning with Xiaomi Mi 9 but bad(bend) results, what camera can I use?

Post by bensan »

Hello everyone. In the last three months I have been working on a digitization project of an old magazine. In total I scanned 122 magazines (text and images) with 30 pages on average. For this I used my phone (a Xiaomi Mi 9 Lite 18MP), some headphones to control the taking of the photos, a microphone holder adapted to support the phone, a mat and a glass.

The result was mixed. While the capture of the photos was relatively fast, the photos tended to distort (bend) at the corners, especially at the bottom. And on the sides of the pages the photos tended to be blurry some times. In the end, it took longer to edit the photos (with GIMP) to remove the bending a bit, and in Scan Tailor it also took a while to use the “dewarping” tool. Of the 122 magazines, about 85 were using this method. The rest I did with an old multifunctional scanner. The scanning process was slower, but in the end the processing in ScanTailor was dramatically faster.
The question that arises, and that is why I want to consult you, is if using another camera I could avoid post-processing in GIMP and SacanTailor to correct distortions.

What cheap modern camera could I use?

I have reviewed the Canon Eos Rebel T100 18-55mm Iii Kit and Canon PowerShot Elph 160, however it appears that the former has no manual remote control (only via the Eos utility software). I am afraid to buy a camera and that it has the same problem as the Xiami Mi9 Lite.

What other advice could you give me? Should I buy a better scanner? Or should I keep using the scanner camera method for future projects?

Thanks!
Vidar
Posts: 12
Joined: 17 Sep 2012, 17:18
E-book readers owned: Kindle Paperwhite, Kindle Oasis
Number of books owned: 400
Country: Norway

Re: Scanning with Xiaomi Mi 9 but bad(bend) results, what camera can I use?

Post by Vidar »

I will suggest a Canon G10. It's old, but can be easely found on ebay. You you don't need more pixels than it has for book pages and OCR. It's the newest and best compact that can be tethered og give a live vewfinder on a Windows PC through PSRemote or some free software found on Canons site.
rkomar
Posts: 90
Joined: 12 May 2013, 16:36
E-book readers owned: PRS-505, PocketBook 902, PRS-T1, PocketBook 623, PocketBook 840
Number of books owned: 3000
Country: Canada

Re: Scanning with Xiaomi Mi 9 but bad(bend) results, what camera can I use?

Post by rkomar »

I would also suggest that you position the camera farther away and zoom in if possible. That usually improves the problems you saw (depth of field and lens distortions).
rkomar
Posts: 90
Joined: 12 May 2013, 16:36
E-book readers owned: PRS-505, PocketBook 902, PRS-T1, PocketBook 623, PocketBook 840
Number of books owned: 3000
Country: Canada

Re: Scanning with Xiaomi Mi 9 but bad(bend) results, what camera can I use?

Post by rkomar »

I should also add that you can simplify processing with gimp by using batch commands if your undistort operation always uses the same parameters. Here are some notes I made on the subject a few years ago:

gimp batch commands:
(args: filename/pattern main edge zoom brighten xshift yshift)
> gimp -i -b '(simple-lens-undistort "k.png" -38 0 0 10 0 0)' -b '(gimp-quit 0)'
> gimp -i -b '(batch-lens-undistort "*.png" -38 0 0 10 0 0)' -b '(gimp-quit 0)'

The first example is for a single image, and the second is for multiple images selected using a pattern. You can play with gimp manually to see what the best values for main,edge,zoom,... are, then write a shell script to automatically apply those parameters in a batch process after that. The same parameters should apply if you always set up your camera the same way each time. Processing with gimp is slow, but you can go do something else while waiting for the batch to run.
dpc
Posts: 356
Joined: 01 Apr 2011, 18:05
Number of books owned: 0
Location: Issaquah, WA

Re: Scanning with Xiaomi Mi 9 but bad(bend) results, what camera can I use?

Post by dpc »

This article may help you understand what is causing the distortion you're seeing and what you can do about it:

What is Lens Distortion? Barrel vs Pincushion Distortion
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