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

Simple, easy to build, ~600pg/hr, very portable scanner

Built a scanner? Started to build a scanner? Record your progress here. Doesn't need to be a whole scanner - triggers and other parts are fine. Commercial scanners are fine too.
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Mohib
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Re: Simple, easy to build, ~600pg/hr, very portable scanner

Post by Mohib » 10 Apr 2014, 21:48

Yes it would "kill" the elegance not to mention the design objectives! :)

However, I think this is where merging software and hardware to achieve desired end results allows us to make the most effective, most efficient and most economical use of all the resources we can bring to bear on a problem and solve issues where they are easiest, least expensive and also most flexible.

For example, software to de-keystone, de-warp or de-skew images are all simple and elegant solutions to correct image artifacts -- that are the result of an "imperfect" hardware system -- and save the expense and effort of making every single scanner a precision mechanical system while still achieving acceptable results. Similarly, image scale drift as just one more image artifact which arises from an "imperfect" hardware system which can also be solved very simply and efficiently with de-scaling software -- saving the expense and complexity of additional hardware to fix the platen-camera distance -- and thus allows for much simpler scanner designs, even for two camera systems.

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Re: Simple, easy to build, ~600pg/hr, very portable scanner

Post by daniel_reetz » 10 Apr 2014, 22:29

I agree completely. One of my design goals with the "hackerspace scanner" is to do *everything* correctly in the physical world, and it has a cost. (note: there's still a ways to go to meet that goal). Why that goal? Because I want to sum up the knowledge generated here in a physical form, make it widely available, and then (while always having it available) move on to more interesting and futuristic approaches.

The ideal scanner is basically no hardware; a perfect scanner is made out of nothing. We can substitute computation for hardware. The way to do that is to capture a rich representation of the book via special cameras, and to compute the result after the fact.

The closest we've come to a practical no-hardware scanner, IMO, is the laser-based work I did with Steve1066D and Anonymous2 (&others). The whole scanner would be based on a single camera, an LED, and two laser diodes. And we'd have millions of pixels worth of depth resolution.

The basic problem is that we need more programmer power to get there. I'm studying Python right now, but I'm a long way from writing those kinds of algos in a usable form.

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Re: Simple, easy to build, ~600pg/hr, very portable scanner

Post by Mohib » 10 Apr 2014, 22:55

Not sure if this scanner has come up here, but it's a classic example deliberately making a "flawed" mechanical system and correcting the images in software all to achieve a novel design that allows scanning at 15,000 pages per hour. It seems to be an R&D project at the University of Tokyo which has resulted in what looks like a spin off consumer version (see second video):



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Re: Simple, easy to build, ~600pg/hr, very portable scanner

Post by dpc » 10 Apr 2014, 23:08

Of course in theory you're correct. At this point though, I'd rather spend more time with my scanner design so that I don't need to do any more steps in post-processing that might require manual intervention. Today it takes me much more time to process images than it does to acquire them. If I can do something once (either with the scanner design, camera/lens quality, or pre-scan setup) that reduces what I have to do per-page when scanning or on the backend post-processing I think that's a worthwhile investment.



On the topic at hand, the scanner design described in this thread reminds me of another simple design that is somewhere in these forums (I couldn't find it). That design had a platen that was attached to a pair of bars that went back to a cross-member that served as the camera mount. Here's a crude side-view drawing of it:

Image

To turn the page the vertical portion of the book is lowered, the camera tilted back, swinging up the platen, page turned, platen lowered back into the book gutter, and the book half lifted back vertically and pressed against the platen glass. I wish I could have found the post describing this because I believe it included a video demonstrating how easy the process was. The genius of this simple inexpensive design is that the camera is fixed to the platen position/orientation so there are no keystoning or focusing problems.

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Re: Simple, easy to build, ~600pg/hr, very portable scanner

Post by Mohib » 11 Apr 2014, 00:02

That's an interesting design.

I'd be curious what kind of speeds were achieved given the ergonomics to perform the key tasks of a) triggering the shutter, b) lifting and holding the platen up while c) turning the page and then after lowering the platen d) pressing the back of the book against the platen to flatten the page. More particularly, I'm wondering if pressing the book against the platen (and that with one's left hand) would get tiring especially while also making sure the other side of the book is pushed "flatish" so it's out of the way and not in the field of view (as is a problem with paperbacks) and to also allow print that is close into the spine be imaged as flat (and with little or no warping) as possible.

As for the fixed camera position, it would seem to me that there would still need to be a way to move it vertically (since tilting would cause keystoning) because it's not necessary the centre of the platen will be the centre of the book if you have a smallish book and zoom in to fill the field of view to get better resolution on smaller page sizes.

Also since the camera view finder is off to the side, it would seem to me that it would be hard to keep tabs on the placement of the book in case it drifts or slides to ensure it's still imaged fully and not being clipped.
Last edited by Mohib on 11 Apr 2014, 00:51, edited 1 time in total.

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Re: Simple, easy to build, ~600pg/hr, very portable scanner

Post by rkomar » 11 Apr 2014, 00:20

I would guess that no change is ever made to the zoom factor once it is set up to get the whole of the glass plate into the picture. For small books, you just crop away a lot of the picture around it. That's the price you pay for a simple, unchanging setup.

I also had the same questions about the ergonomics of it.

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Re: Simple, easy to build, ~600pg/hr, very portable scanner

Post by daniel_reetz » 11 Apr 2014, 01:14

Mohib wrote:Not sure if this scanner has come up here, but it's a classic example deliberately making a "flawed" mechanical system and correcting the images in software all to achieve a novel design that allows scanning at 15,000 pages per hour. It seems to be an R&D project at the University of Tokyo which has resulted in what looks like a spin off consumer version (see second video):


Yeah, we built a laser-based system (as far as I know) before they did. The idea is to turn pages as fast as you humanly can, and have the computer do the dewarping. Here is what the hardware looked like:

http://diybookscanner.org/forum/viewtop ... =230#p8972

Check out this first result from Steve1066D - who got a very high quality depth map in no time:
http://diybookscanner.org/forum/viewtop ... t=70#p8457

If you look closely, you can see that the rotation of the book is also given by those two lines.

DPC, I seem to remember it being related to the words "air platen" and to the user "sdati" http://www.diybookscanner.org/forum/vie ... 4&start=10


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Re: Simple, easy to build, ~600pg/hr, very portable scanner

Post by dpc » 11 Apr 2014, 15:24

daniel_reetz wrote:DPC, I seem to remember it being related to the words "air platen" and to the user "sdati" http://www.diybookscanner.org/forum/vie ... 4&start=10
Thanks Dan, but that's not the post that I recall seeing. He had a DSLR attached to something much simpler than what is shown on the video you posted. It was just a platen and some way to fix the camera to it a foot or so back from it. It may not have been in it's own thread on the forums which is probably why I can't find it.

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Re: Simple, easy to build, ~600pg/hr, very portable scanner

Post by Mohib » 17 Apr 2014, 18:35

I've posted more details on the trigger hardware over in the Camera Triggering thread here:
http://www.diybookscanner.org/forum/vie ... =40#p17640

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Re: Simple, easy to build, ~600pg/hr, very portable scanner

Post by gaferna » 27 Apr 2014, 21:12

Mohib

May be you refers to this project

http://www.diybookscanner.org/forum/vie ... ?f=1&t=175

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