super leightweight, super cheap, uncomplicated book scanner

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super leightweight, super cheap, uncomplicated book scanner

Postby unbelift » 22 Apr 2010, 11:40

I wanted to share my setup for my book scanner.
It's super leightweight, super cheap and uncomplicated.
IMHO the best thing about it is the method to hold down the pages.

Power Supply:
I use two Canon Powershot cameras which I power via two voltage regulators
(LM350). Although the cameras have 4.3V printed near the plug for external
power supply, I found out that they start working somewhere above/around 5V. Since
four AA batteries amount to 6V I run both cameras somewhere at 5.8V which
seems to be fine. As the main power supply I use a universal adapter rated
for 2A which I've set to 9V. Attached are the two LM350 each configured with
their standard circuit (one potentiometer 5k, two capacitors, one resistor)
It seems that you need to use regulators that can provide the 2A for short
periods that the original Canon power supply provides. I used weaker
regulators before which did not provide enough current once the motor for
the zooming kicks in. As for the power plugs: outer diameter is 4mm which
fits perfectly.

Holding the book:
I've cut one Leitz folder in two and used duct tape to fix the halves to L-shaped
book stands like this: L\_/_I (The boxes in the pictures only support the cameras)
This setup is quite sturdy since I also used duct tape to connect the book
stands at the bottom - this way they don't move once pressure is applied
from the top.

Holding down the pages:
This is the best part in my opinion.
I got some 8x8mm aluminium sticks (hollow) and cut them to convenient
lenghts. Duct tape again and a bit of bike inner tube were used to create
the size adjustable setup seen in the picture. One hand is enough to hold down the pages.
All the aluminium weights about 150g - no kilograms needed to be lifted.

Getting the pictures:
I attached both cameras to my computer.
I use gphoto2 2.4.9 and the following perl script to get the images from both cameras. The
timing is such that once I have turned the page the images are usually
transferred. I need to remove the flash cards from the cameras in order to
get "/main/settings/capturetarget 0" working with gphoto2.
So no batteries needed plus no wearing of flash cards involved.

The way the script is written, I only have to push ENTER to take the two
pictures simultaneously. In combination with the usb keyboard in the
picture, this is really convenient. (Possibility: there are seperate usb
number pads. That would take less space since I only need the ENTER key.)

Setup the camera, to be run for each camera:
Code: Select all
#!/bin/sh
gphoto2 --shell --port $@<<EOF

set-config /main/settings/capture 1
set-config /main/settings/capturetarget 0


#set-config /main/capturesettings/zoom  3
set-config /main/imgsettings/whitebalance 6
set-config /main/imgsettings/imagesize 1
set-config /main/imgsettings/iso 2

set-config /main/capturesettings/shootingmode 2
set-config /main/capturesettings/aperture 3
set-config /main/actions/focuslock 1
EOF


Code: Select all
#!/usr/bin/perl

$counter=0;

while (1){

readline();

$pad = "%.3"."d";

$number=sprintf($pad, $counter);

system('/opt/gphoto2/bin/gphoto2  --filename "'.$number.'-%m-%d-%H-%M-%S left.jpg"  --port "usb:002,043" --capture-image-and-download &');
$counter++;
$number=sprintf($pad, $counter);

system('/opt/gphoto2/bin/gphoto2  --filename "'.$number.'-%m-%d-%H-%M-%S right.jpg"  --port  "usb:002,042" --capture-image-and-download  &');
$counter++;

system('/home/m/bin/waitfor-gphoto2');

}



/home/m/bin/waitfor-gphoto2:
Code: Select all
#!/bin/sh

name=/opt/gphoto2/bin/gphoto2

instances=1
while [ $instances -gt 0 ]; do
        instances=`ps -e -o command|grep "^$name"|wc -l`;
        sleep 0.2;
done

aplay /home/m/permanent/sounds/submarine.wav &




Overall cost except cameras should be about 10 EUR.

BTW: The big speaker magnet in the picture is only there to hold down the
stick while I take the picture :-)
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Re: super leightweight, super cheap, uncomplicated book scan

Postby daniel_reetz » 22 Apr 2010, 21:18

Awesome design! Thanks for documenting it so well, and for sharing your code.

How long does it take Gphoto2 to transfer the two images? It doesn't have any problem supporting 2 cameras at once?

Do you have any problems with your glassless platen?

Again, love it. Thanks for sharing!
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Re: super leightweight, super cheap, uncomplicated book scan

Postby unbelift » 23 Apr 2010, 07:36

Nice to find that you like it :-)

I just did a timing test: removed the loop and measured the time from starting the script to exit.
It's ten seconds to take two pictures and to be ready for the next.
That's not superfast but ok for me. In theory, that's 720 pages per hour...
This is for Powershot A80. Newer cameras may be faster.

For gphoto2, you can specify the usb address of the camera, so there's no problem running two instances at the same time.
(In my script, gphoto2 runs as a background job both times. So it's truly parallel.)

The glassless platen works perfectly for me. It's maybe not as easy to handle as other constructions since the angles are no that stable.
That means that I need both hands to place it onto the book with everything lining up, then apply pressure parallel to the page towards the center of the book from one side to hold down everything. At this point, everything is stabilized by friction. And I can take the picture with the other hand.
It may sound more awkward than it is, but it isn't.
For me it beats everything because it does not take up space in my suitcase :-D
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Re: super leightweight, super cheap, uncomplicated book scan

Postby dtic » 23 Apr 2010, 12:51

Nice! I like the direct computer connection, bypassing the need for memory card and for a separately powered trigger. I'd like to see a video of this in operation though. The platen seems tricky to handle.

Some other ideas:

Have you thought about adding lockable joints to the now duct taped platen edges? I have an old broken Ikea lamp lying around that I'll try to reuse for that, it has the kind of joints I'm thinking of but needs to be trimmed down. With wing nuts it would still be easy to assemble/disassemble for each use.
40088_PE079702_S4[1].jpg
40088_PE079702_S4[1].jpg (16.77 KiB) Viewed 8715 times

http://www.ikea.com/us/en/catalog/products/20370383

Would adding a horizontal bar to the edge closest to your chest (making that end of the platen a triangle) add enough stability to lift it with one hand?

Would you gain speed by placing the keyboard on the floor and use the foot to trigger shots? Alternatively, stores like dealextreme have very inexpensive USB foot swiches and numpads. Another alternative is voice control. (http://www.dealextreme.com/details.dx/sku.22175 , http://www.dealextreme.com/search.dx/search.numpad )
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Re: super leightweight, super cheap, uncomplicated book scan

Postby unbelift » 24 Apr 2010, 06:01

Hmm. Just prepared a small video only to find out that it's not allowed to upload it. (It's only 190K big...)
I can send it to you if you want. (Just give me an email address.)

Lockable joints may be an idea. It might be even easier to get a 90° bracket and fix that with wing nuts.
Plus the triangle idea would definitely add stability.

I don't think that using my foot would add speed. Plus it would put me in a non-ergonomic tensed position (I think).
The time frame is really set by the 10 seconds necessary for each shot, so pushing a button is not an issue.

It works nicely for me the way it is - but these are definitely improvements. Thanks :-)
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Re: super leightweight, super cheap, uncomplicated book scan

Postby daniel_reetz » 24 Apr 2010, 09:42

unbelift wrote:Hmm. Just prepared a small video only to find out that it's not allowed to upload it. (It's only 190K big...)
I can send it to you if you want. (Just give me an email address.)


You mean the forum will not accept it? That's weird -- please let me know the error you are seeing.
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Re: super leightweight, super cheap, uncomplicated book scan

Postby unbelift » 24 Apr 2010, 12:29

The error message was that .mp4 is not allowed as an extension.
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Re: super leightweight, super cheap, uncomplicated book scan

Postby mathesonmd » 25 Apr 2010, 07:12

I don't think that using my foot would add speed. Plus it would put me in a non-ergonomic tensed position (I think).


This is why I decided against a foot pedal. I use one almost everyday in surgery for cautery and it forces you into uncomfortable positions when you are constantly needing to have one foot floating off the ground. After several hours it can give you a sore back. Our other cautery is activated directly on the handpiece (Bovie) and I notice when I've used this more I'm much more comfortable.
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Re: super leightweight, super cheap, uncomplicated book scan

Postby daniel_reetz » 25 Apr 2010, 09:32

unbelift wrote:The error message was that .mp4 is not allowed as an extension.


If you would, please try it again.
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Re: super leightweight, super cheap, uncomplicated book scan

Postby unbelift » 25 Apr 2010, 10:57

mathesonmd wrote:This is why I decided against a foot pedal. I use one almost everyday in surgery for cautery and it forces you into uncomfortable positions when you are constantly needing to have one foot floating off the ground. After several hours it can give you a sore back. Our other cautery is activated directly on the handpiece (Bovie) and I notice when I've used this more I'm much more comfortable.


It amazes me how uncomfortable some setups are in the OR - after all they are mostly designed by doctors who should know better. I was assisting lots of arthroscopies during my last internship and seriously consider buying myself one of these weightlifters belts for the next time.

Hehe. The book in my first picture is Harrison's Internal Medicine :-) The one in the video I'm attaching now as a zip (because mp4 upload does not work) is Pathologic Basis of Disease ;-)
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