using a single camera + batch dekeystoning

[Canadane]

Greetings,

I read the old Instructables about six months ago and am finally ready to build myself a scanner - it's amazing how much the community has developed! Unlike the upside-down build recently posted, I want to take a picture of two pages at once using a single camera and a platen. Has anyone had luck mounting a single camera directly above the platen to capture both pages at once then batch processing the images to dekeystone and separate the single image into two page files? I already own a cannon d30 with remote shutter release that should be beefy enough to get enough detail to make it work, but I hope to accommodate (currently unknown) problems while still in the design faze.

Also, any tips on platen angle for this application would be greatly appreciated! I've read about people using 120 degree or 90 degree setups but I couldn't find any posts that address the issue directly. I guess I could design a variable angle platen, but I'd really rather not! What do you consider when making this decision?!

For clarity, here are my specific questions:
1) Has anyone done batch processing for dekeystoning off-angle pictures of pages flatened by a platen?
2) Are there any setup problems with this, such as weird reflections off the platen?
3) What angle should I build my platen to be?

Thanks!
Canadane

P.S. I'm sorry if I put this in the wrong category. I settled on hardware because of the recent topographic dewarping discussion

[steve1066d]

1) Has anyone done batch processing for dekeystoning off-angle pictures of pages flatened by a platen?

For fixing perspecitve, BookScanWizard can be used. Right now you'd have to make copies of the pages, because BSW expects that there is only one page per scan. I may add an option to avoid having to copy the pages.

You would want to copy the pages into both an l & r directory, then correct perspective and crop for both sides of the page.

[spamsickle]

I posted a batch dekeystoning process using Photoshop which can create two pages of output for each page of input here. Steve's Book Scan Wizard does most of the same things, and more, but if you already have Photoshop (version 6 or higher) and don't want to duplicate your input into L and R directories, it may be worth a try. Someone in that thread mentioned another alternative to Photoshop, which I haven't tried myself.

The tutorial itself deals with separate L and R images, but I've tested it with a single 2-page input like you're proposing, and it handles that just as well. Anyone who's actually worked through the tutorial there should be able to create the 1-in/2-out script, but if you have questions just ask.

[Canadane]

Thanks so much for the help! I'll post pictures of the build once it is constructed.

[L0g1cM0del]

My build is like this. I'll try and post some pics later this week. I'm still trying to tweak it to find the best results, because right now, using this approach is too time consuming at least with the limited resources I have available to me now. I have my camera around 18" directly over the center of the build. I originally had intended for it to take a picture of 2 pages being pressed flat with a glass, but I was really worried about paperbacks because it was too much stress. Right now, I have my V base made of a cardboard box (limited supplies). The angle for it is close to 105 degrees because I found that that angle seems to work the best at least at the moment. I think at some point when I can redesign it, I would like to make an adjustable V base for larger books that would be flexible for different shapes too. I just don't have the time or resources now to really do it.

I don't have a glass platen yet, but I have tried putting a small piece of glass from a picture frame over top one page, and I don't really have any glare issues because my lights are directly parallel with my camera coming straight down. I was thinking in terms of platen design maybe get one large piece of lexan and use a heat gun to shape the inner part so that it would be rounded and that would compensate for small paperbacks. I think rob demonstrated this somewhere in the forums but am not sure where it is. I think the downside to this would be possible scratches.

In terms of the dekeystoning, I have run a few pictures through ScanTailor with the dewarping and they come out decent. It has some trouble deskewing the pages correctly, so I have had to manually correct for that which is very time consuming. The dewarping works, but sometimes I still may have to make manual adjustments. One thing I noticed though is that the words seem to be stretched a little tall. They are still readable but it just looks kind of odd. It is probably due to the angle of the words.

I have only done a few pages like this because the manual corrections are very time consuming but am still trying to improve the overall design. I'll try and post pics of it later on to help out.

[lorenzodow]

I'm curious about how this has worked out. I just keep admiring everyone's work on here but can't be bothered to shoot with two cameras (or to make a platen...I know, better input...). That said, I've actually had some books come out pretty well with a single camera probably open to about 150 degrees (using books that already want to open that far), using things I have on hand to prop them open, and usually a tripod/camera and a light. I've used Scan Tailor and its automatic dewarping, which sometimes does a tremendous job.

Anyway, I'm curious about how your project has been going because I would like to figure out a build that uses a single overhead camera scanning two pages at once and then straightening things out in post.