Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

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by mhr
14 Aug 2013, 03:02
Forum: Tutorials/How-To's
Topic: Dewarping with a regular calibration point grid
Replies: 18
Views: 20422

Re: Dewarping with a regular calibration point grid

I just saw a few days ago the activities of Abmartin . In the thread http://www.diybookscanner.org/forum/viewtopic.php?f=19&t=2795&start=20 an updated version of my program ppmunwarp is presented to obtain PPI information. I updated my program to calculate this information in a hopefully more precis...
by mhr
28 May 2012, 10:26
Forum: Tutorials/How-To's
Topic: Dewarping with a regular calibration point grid
Replies: 18
Views: 20422

Re: Dewarping with a regular calibration point grid

And here is the program called ppmunwarp , which does the actual calibration. I've chosen the GPL copyleft policy: COPYING.txt The program source consists of one C++ file ppmunwarp.cc.txt Please drop the .txt extension. That was necessary to allow this file as attachment for this post. The program d...
by mhr
28 May 2012, 09:25
Forum: Tutorials/How-To's
Topic: Dewarping with a regular calibration point grid
Replies: 18
Views: 20422

Re: Dewarping with a regular calibration point grid

Some example images are given in this post for demonstration purposes. I scaled them down for file size. Note that this is just a rough test with limited precision. Precision is really increased by a perfect setup. First the camera shot of the calibration grid: calibration_grid_hand_made_warped.jpg ...
by mhr
28 May 2012, 08:29
Forum: Tutorials/How-To's
Topic: Dewarping with a regular calibration point grid
Replies: 18
Views: 20422

Re: Dewarping with a regular calibration point grid

To unwarp a series of pictures, first of all a picture has to be taken with the calibration grid at the defined paper position. The inplane rotation is not crucial, because programs like scantailor are very capable to correct these final inplane rotations perfectly. Then the book pages (or whatever ...
by mhr
28 May 2012, 07:38
Forum: Tutorials/How-To's
Topic: Dewarping with a regular calibration point grid
Replies: 18
Views: 20422

Re: Dewarping with a regular calibration point grid

First of all, a suitable calibration grid has to be created. The program needs colored points and defaults to red points to make point detection in images an easy task. If you have no color printer, you can make one by hand using a gridded paper and marking a regular grid with a red marker pen. Note...
by mhr
28 May 2012, 06:38
Forum: Tutorials/How-To's
Topic: Dewarping with a regular calibration point grid
Replies: 18
Views: 20422

Dewarping with a regular calibration point grid

Hello all, I refer to the post viewtopic.php?f=17&t=113&hilit=calibration , in which a calibration point grid is suggested to do a calibrated dewarping if the camera has a fixed position with respect to the scanned page. There are other approaches like viewtopic.php?f=13&t=784 to automatically recog...
by mhr
25 May 2012, 03:55
Forum: Scan Tailor
Topic: 0.9.11.1 release
Replies: 7
Views: 8821

Erroneous keyboard shortcuts in german version

This is a bugfix release. The most important bug fixed was affecting binarization quality in Mixed mode. Another one caused cyan instead of white borders in certain circumstances. Both were sitting there for a long time. Everyone is urged to update. Hello Tulon, using Your very nice scantailor prog...