Notes on my version of the cardboard book 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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whengreg
Posts: 2
Joined: 29 Mar 2022, 14:35
E-book readers owned: None
Number of books owned: 100
Country: America

Notes on my version of the cardboard book scanner

Post by whengreg »

I used the cardboard book scanner, but with a couple interesting changes.

First, the glass. I bought a 8.5x11" photo/document frame with the least obtrusive frame I could find. I removed the glass, used a hammer to knock out one of the long sides, used a saw to remove the two triangle ends, cleaned up the rough edges with sandpaper, replaced the glass, and used packing tape to secure the glass to the U-shaped frame. This feels rather sturdy while still allowing for rapid repositioning. The side without a frame goes towards the book spine. (Note that with my current cradle, using a saw to remove the triangle bits isn't required because there's a hollow below the cradle. This is good because that was the most annoying part of making this.)

Second, for the cradle, I tried the whole "cutting a box in half on the diagonal" thing, but I don't think it works that well. The two halves moved around too much, the flaps on the top/bottom of the original box kept the book from resting stably, it's difficult to aim for a specific angle, it's just not a great design. Instead, I started with an open cardboard box, put a book in the bottom to get the height just right, put a piece of folded cardboard on top, then taped it all up. (And cut a notch for easier access to the glass.) This is remarkably sturdy, you can get the exact angle you want for the cradle by simply varying the book(s) you use, (I got around a 115 degree angle) and it requires less space. Note that the cradle is not symmetric; the side with the notch is sitting flush on the top flap of the base box, while the other is at an angle. This was to have the side that takes more abuse be stronger.

I experimented with using a cellphone for a camera. This has some interesting features in the ability to have a choice in camera software, cheap remotes, the possibility of voice control, and the ability to use a camera that you probably have in your pocket already. Unfortunately, it doesn't work for one obvious (in retrospect) reason: cellphones don't have an analog zoom. This puts a lot of pressure on positioning, but the closer you position the phone, the more reflected light you have to deal with. Or you can position the phone normally, and simply discard most of the pixels, but then your fancy 16MP phone is worse than an 8MP camera. (While phones exist that have "optical" zoom, they're a lot more expensive than a basic camera. Also, clip-on zoom lens exist, but I don't trust the optics on a $10 item from eBay.)

For completeness sake, the light is a 2500 lumen LED, which I'm not happy with (there's a substantial spotlight effect; still working on this), the tripod is a piece of junk I got for free that's falling apart but still good enough for the job, and the camera is a Canon Powershot 1400A (which I got because of the 3rd-party firmware and automation ability, which I haven't actually used. Any 16MP camera that allows setting a manual white balance should be fine.)
stand1.jpg
An example output image. (I just rotated and cropped it, no other processing was done) Note the substantial difference in the brightness between the top and bottom.
output2.JPG
whengreg
Posts: 2
Joined: 29 Mar 2022, 14:35
E-book readers owned: None
Number of books owned: 100
Country: America

Re: Notes on my version of the cardboard book scanner

Post by whengreg »

A follow-up, now that I know what I'm doing more:

Glass:

I eventually stopped bothering with the actual frame, and just used Scotch Tape around the outer and lower edges to make sure I didn't get cut on the glass. This allows the glass to sit closer to the backing, and makes it lighter. I did not tape the upper edge, so I could digitize slightly larger books.

I also grabbed a second, larger, picture frame, and did the same thing to it, because I had some books that didn't fit. It's more unwieldy, so I only use it if needed, but it's there if I do.

I put some packing tape along the upper-middle in order to create a pull tab for when it's close to the background, and difficult to lift up.


Cradle:

I'm still using nearly the same cradle. I ended up placing a more rigid board on top to act as a background to the photographed page, because the cardboard was starting to give way there a bit, but I didn't see the need for a any other changes. (This board was the backing from a picture frame, the same one I got the glass from.)


Camera:

* You want a camera with at least 8MP. There's no great reason to go above 16MP unless you're scanning books with extremely large pages.
* The camera should have a manual mode, where you can set both aperture and shutter speed. This is important for consistency between pages. A camera that automatically determines aperture will do so based on the overall brightness of the "scene", which will mean pages will have inconsistent brightness based on how much text is present. This is why I eventually switched cameras.
* You want a camera with optical zoom. (This excludes most cellphone cameras, which would otherwise be suitable.) The lack of zoom means you're either discarding a bunch of pixels, or need to position the camera close enough to the page that it'll get weird reflections and/or a fisheye appearance to the page. Either way, not ideal.
* The ability to add a remote is nice, but only needed if you want a second camera.

You can see if a camera can set manual aperture by searching for the camera's model + "manual", which will usually turn up the manual. The Canon Powershot SX line is a good option if you don't want to think about this decision too much. I picked up a PowerShot SX150 IS from eBay; I assume the other models in this line also have this ability, but check before buying. (This camera only has 12MP; going higher might be desirable.) Also, make sure you have power sorted out. The SX150 uses AA batteries. (Works fine with Eneloops, but not with some rather old NiMH batteries I had lying around.) With lithium batteries, the capacity drops over the years, so buying old cameras that use lithium can be iffy; also any replacement batteries you can find on eBay are probably old stock, which will have the same issues. So, expect to leave the camera hooked up to A/C.

Also be aware of Minimum Focus Distance. You want a lot of megapixels in the resulting image, which means you want to be zoomed in, but for a given zoom setting, there's a minimum distance to the subject. This is a weakness of the SX150; I would usually prefer to zoom in a bit more than I can. Unfortunately I'm not sure if there's a good way to research this before purchase.


Lighting:

I reduced the spotlight effect by moving the light further away. I got rid of the reflection from the camera by hanging a bit of cardboard off the edge of the light. I'm otherwise still using the same setup. There's still a difference in the brightness across the page, but it's not as obvious now.
Current setup
Current setup
Here you can see my current setup.
Example output of current setup
Example output of current setup
And an example output image. The weird colors are from the original.
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