Dailing in the Atiz DIY Scanner

March 4, 2011

My modifications to the Atiz DIY scanner to optimize image quality and speed.

As a rabid scanner and collector of books, it quickly became obvious that a flatbed scanner was not going to be cost effective. Reviewing the options, I decided upon the Atiz DIY Scanner. Two features where important to me. Speed the Atiz uses Canon DSLR cameras to quickly capture the pages of the book and this naturally leads to the next feature which is that the Atiz is also Non Destructive.  This means that you do not have to cut the binding from the book. This was especially important due to my interest in books that where out of copywrite.

Once received building the scanner itself took about an hour. Well time to plug it in and start scanning. Well if it was only that easy.

Choice of lens

The recommended lens setup is the Canon 50mm fixed focus lens. This is probably my favorite photography lens due to its rather large aperture (light gathering capabilities) and price. In some cases less then $50. Typically $80 retail. A great lens just not great for my choice of camera. I chose the Canon Xsi which at the time was the highest resolution camera from Canon available at 12 mega pixels. This equated to just less than 300 dpi for the documents I was scanning. Perfect for OCR. Well the CMOS sensor on the low consumer grade cameras (i.e. the ones less then $1000) is not a full 35mm sensor but a truncated dimension. This turned my 50mm lens into an (50mm x 1.6=) 80mm lens. There simply is not enough travel on the camera mounts to account for this conversion factor without cropping the document pages. I could indeed get the entire page on the scanner but I had to move the camera so far back that the actual page was only a fraction of the usable image space. Effectively reducing my DPI measure, which was not the objective. So off to choose a different lens. At this point, my total cost for the system is about $10,000 so price is an object at this point I ended up choosing the Tamron 55-200mm zoom lens. With this setup, I can move the camera far enough back and zoom onto the page to capture the page and fill in the entire usable image space. There is some pin holing on the images but most modern OCR system can handle this. This use of the zoom lens actually makes the book setup much faster then with a fixed lens and I can optically magnify books that are smaller formats. (In some cases, I have found valuable dictionaries that are less then 5 inches tall)

Adjusting the self-centering mechanism.

After switching out the lenses, I found that the self-centering mechanism was not functioning properly. As you move through the book, the spine should self-center saving you readjustment of the cameras. This needed to be raised a bit to avoid binding on the lower support beam. This is accomplished by loosening the bolts under the bottom book support.

Self Centering Enlarged

Centering the cameras

The camera mounts are not self-centering. Therefore, you need to adjust the angle using a long yardstick or other measuring device. I simply lay it across the book mounts and take photos until the center measurement is in the center of the captured image and both images from my right and left camera appear at the same scale. I would have preferred to use a level but the Canon cameras do not have a level back plane on which to mount the level.

Overhead lighting

Capturing of books goes smoothly until I find an older book, which has the text rather close to the spine. It became obvious that I have some major glare issues where the seam of the clear scanner plate is bent at at 45 degree angle. This creates a concave surface that is guaranteed to shine the overheard light right into the camera. At first, I assume I can simply polarize the light source and put a linear polarizer on the camera. This does not work in practice, as the auto focus mechanism will fail to work if you use a polarizing filter. So removing the lighting from the top of the scanner was required. At first, I simply mounted a few home depot florescent lights on the wall that the scanner was located. This worked very well and eliminated the glare issue. Once I performed more OCR the gradient of the lighting across the page while not visible to the human eye was creating artifacts for the OCR system. I then mounted linear LED lights on both sides of the scanner just above my head and replaced the florescent lights on the far wall. [photo] This works well but can be dark for color photography. Luckily, I am scanning only books with text in them.

Offset Lights

LED Lighting Closeup

LED Lighting Closeup

 

LED Mounting Method

LED Mounting Method

Wood Clamp Stablizer

Wood Clamp used to Stablize LEDs

Plastic Clamps Closeup

Plastic Clamps Closeup

Stick Holding LED lighting Clamps to Shade

Stick Holding LED lighting Clamps to Shade

 

 

Protecting your Camera

To get the correct angle on the cameras I resorted to placing a few business cards at the bottom of the camera where it pressed against the camera mount. This allows me to adjust slighting the angle of the camera. This worked out great until I loosened on of the cameras too much and it dropped on the platen. Luckily the camera and platen where unharmed. Now I have some old shoelaces holding the camera up in addition to the camera mount. Stupid looking but better safe then sorry. [photo]

Extending the shroud

I extended the original shroud to the tabletop to avoid glare from the white colored wall at the far end of the scanner.

Renfrew tape is your friend

Some of the wires I used where white for the LED lighting. Simple renfrew tape available from any sporting store can easily recolor the black.

Software tweaks

The DIY software is a bit buggy but usable. However, in some cases they get out of sync with the client capture system. In this case, it is an easy matter to copy the Canon SDK (.dll files) to the home directory of the client software to allow control of new cameras.

I have had issues with memory leaks and race conditions that forced me to restart the capture software to scan large books. Some of these errors are random and are perhaps actually in the Canon SDK themselves. This does not have much of an effect on my actual processing of documents other then it is annoying.

In the future, I will probably be writing my own capture software to avoid these issues. I already have an imagej script to post process images.

Would I recommend you buy one of these? I am not sure. For the money, it is effective. Like all things automated, it is a bit finicky and less then you would expect for the price. However, given the alternatives for me it is worth it.

Tags:

3 Responses to Dailing in the Atiz DIY Scanner

  1. Ysk on May 10, 2011 at 12:49 pm

    Hi. I am Atiz user in Japan. I was very impressed with your blog post.
    It was very imformative and useful. Please update more clear photos and the details about self-centering and overhead lighting.
    Thank you.

  2. admin on May 10, 2011 at 1:50 pm

    Ysk,

    Thank you for the feedback. I will try and get new photos out soon.

  3. admin on May 12, 2011 at 3:01 pm

    I have updated the photos. Let me know if this is not clear enough.