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

Color shift? Dark room?

Don't know where to start, or stuck on a certain problem? Drop by and tell us about it. Feel like helping others? Start here.
Post Reply
0kelvin
Posts: 25
Joined: 10 Nov 2012, 17:14
Number of books owned: 0
Country: Brazil

Color shift? Dark room?

Post by 0kelvin » 02 Jul 2015, 10:25

There are numerous books scans out there. I'm curious about one thing: I've found some linear algebra and calculus books that, originally, are cyan colored (gradients in the background, colored titles, colored numbers, graphs, etc). I don't know what the hell the person did to the book, but the PDF has all cyan colors shifted to magenta, making the whole book pink. The curious fact is that this didn't affect the photographs in the book, so if there is a picture of an airplane with a blue sky behind it, the sky is blue, yet the cyan/blue text has been shifted to pink.

Another book that I've found was made with a camera, person laid the book on a table and took pics of the pages. However, the whole book is dark! With a bright spot in the middle of it. What is that? Person turned off the lights and took pics with flash on?

duerig
Posts: 360
Joined: 01 Jun 2014, 17:04
Number of books owned: 1000
Country: United States of America

Re: Color shift? Dark room?

Post by duerig » 02 Jul 2015, 11:51

In the first instance, somebody did not have the correct white balance set on their camera for their lighting. This can make all of the colors systematically wrong. I'm not sure why photos seem less affected. Possibly because they are darker or not as homogenously colored as the headings and so the difference is less noticeable.

The second instance you describe is because of uneven lighting. The lights were too close to the page and they were possibly using a spotlight instead of a floodlight. Maybe it could have been caused by a flash, but if there were a flash, you would probably see a white circle of glare in the middle because it is a bad idea for the light to come from the same direction as the camera.

In my first scanner, I had both of these problems. I was using cheap halogen bulbs from the hardware store that gave everything a yellowish tinge. And since I didn't realize there was a difference, I had purchased spotlights. The middle of my scans were always washed out compared to the edges. Changing to a 'Tungsten' white balance and replacing the bulbs made things somewhat better. But it still wasn't perfect until I got an Archivist. :-)

-D

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest