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 royeven
01 May 2013, 17:22
Forum: Tutorials/How-To's
Topic: Preprocessing RAW images for Scantailor
Replies: 37
Views: 29463

Re: Preprocessing RAW images for Scantailor

The more I think about this, the more certain I get that this is related to your version of gimp/linux, and not to ppmunwarp. I suggest we continue this discussion via private email since it won't be relevant to this topic. The error message from "Gimp-Widgets-CRITICAL" and all complaints about "Inv...
by royeven
01 May 2013, 16:43
Forum: Tutorials/How-To's
Topic: Preprocessing RAW images for Scantailor
Replies: 37
Views: 29463

Re: Preprocessing RAW images for Scantailor

Your script is correctly modified according to my suggestions, so it's not the script that is in error. The problem is that gimp is not able to read the descewed file, which in my opinion is very strange since ppmunwarp was able to read it without errors. Could you send me your files for this one as...
by royeven
01 May 2013, 15:41
Forum: Tutorials/How-To's
Topic: Preprocessing RAW images for Scantailor
Replies: 37
Views: 29463

Re: Preprocessing RAW images for Scantailor

Warning: the following post is discussing fine tuning of ppmunwarp and is aimed for those able to read c++ I tested the new autodetection with about a dozen examples. It seems to be right on. Always within 1 ppi of what I manually did, which of course isn't as accurate as the average approach. If yo...
by royeven
01 May 2013, 15:09
Forum: Tutorials/How-To's
Topic: Preprocessing RAW images for Scantailor
Replies: 37
Views: 29463

Re: Preprocessing RAW images for Scantailor

The size of the corrected final photos are exactly the same in the test that went "wrong" and the test I have done now. They seem the same visually. Thanks That's because the error you got was from gimp trying to open the descewed calibration file, not from ppmunwarp descewing your files. I.e., the...
by royeven
01 May 2013, 13:55
Forum: Tutorials/How-To's
Topic: Preprocessing RAW images for Scantailor
Replies: 37
Views: 29463

Re: Preprocessing RAW images for Scantailor

All worked OK leaving those options out! Thanks! Glad it worked for you too. Test B https://mega.co.nz/#!u1pkjKbY!PK9mFR0-Rw_rS8Owq4ScAzYR3UdaemyMqowIs69_gkI In the photo in the middle there is something wrong but the corrected grid is perfect. Obviously because that area receives more light, altho...
by royeven
01 May 2013, 12:00
Forum: Tutorials/How-To's
Topic: Preprocessing RAW images for Scantailor
Replies: 37
Views: 29463

Re: Preprocessing RAW images for Scantailor

I probably should think about adding in some exit codes for failed steps with error messages... I'm not sure how to do that, but the internet probably has the answer somewhere. Exit codes in bash are easy. You could write something like this: if [ condition for exiting the script here ] then exit 1...
by royeven
29 Apr 2013, 13:44
Forum: R&D and New Technologies
Topic: Color and lighting correction techniques
Replies: 6
Views: 10749

Re: Color and lighting correction techniques

Just wanted to way that I think I have solved the problem as to calculate the PPI in software. Feel free to test my solution and gove me feedback so I can make it better. The code is posted here:
http://www.diybookscanner.org/forum/vie ... 975#p15975
by royeven
29 Apr 2013, 13:39
Forum: Tutorials/How-To's
Topic: Preprocessing RAW images for Scantailor
Replies: 37
Views: 29463

Modified version to the scripts, v1.0

Hi abmartin. I have taken the liberty to change a few parts of your script and a few parts of ppmunwarp in an attempt to automate one of the steps that you do manually, i.e. the PPI-detection. I have tested it in ubuntu and debian and think I have removed all the errors, but there might still be som...
by royeven
10 Apr 2013, 13:37
Forum: R&D and New Technologies
Topic: Color and lighting correction techniques
Replies: 6
Views: 10749

Re: Color and lighting correction techniques

Oh, and by the way: You write in your post that you use Gray card (I use an 18%, which has rgb values of 128 128 128) Where do you get this? I don't live in the US, so I probably can't get it from the same place you buy yours, but is it an ordinary standard piece of paper that I can purchase in Euro...
by royeven
10 Apr 2013, 11:54
Forum: R&D and New Technologies
Topic: Color and lighting correction techniques
Replies: 6
Views: 10749

Re: Color and lighting correction techniques

I haven't played with Lightroom in ages, but it used to do what you want it to do. For free: Ufraw. Knowing what you know already, you could do it there. Even better, if you can snap a photo of a gray card in your process, you can fix colors without having to do any math! Ufraw has an excellent bat...