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

Scanning Plastic Books

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skids

Scanning Plastic Books

Post by skids » 11 Aug 2011, 12:20

Salutations to all those wiser than I.

I've been commissioned to scan several photo albums but immediately ran into a brick wall. The pages all have a plastic protective sheet over them causing insane amounts of glare. The photo I attached is a good image. I got this by shining my lights at the ceiling rather than down on the page. Pointing a light source directly at plastic only results in disaster.

I've tried attacking the lighting issue from dozens of different angles but I can't get rid of the ripple effect. Any suggestions?
Attachments
DSCF4057.JPG

the.traveller
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Re: Scanning Plastic Books

Post by the.traveller » 14 Aug 2011, 04:29

Isn't it possible to temporaraly remove the plastic. I have photo albums from the 70's which fall apart because the adhesive plastic has lost it's glue-ing effect. It will take more time lifting the plastic sheet and putting it back, but it will negate the reflection and the curves.

Otherwise you buy an acrylic non glare sheet and put that on top of the page. Because of the surface structure it will almost remove entiraly the glare you are experiencing and maybe the weight will flatten the curves also. (Depending on the plastic used in the album)

Third option is, of course if that is possible, just take al the pictures out and put them in a new album. Since you experience a bubbling effect I geuss that the adhesive glue is finished working so it will be easy to remove the pictures. And if you want the original handwriting then take a picture from them to put them nearby the digital pictures in a web album or similar.

If the album cann't be taken apart, I also advise you to take a picture with a greyscale card, so you can tell Adobe Photoshop or Lightroom to compensate the colour difference.

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Gerard
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Re: Scanning Plastic Books

Post by Gerard » 14 Aug 2011, 22:23

post 2 images of the page with different light positions, then it is maybe possible to calculate the image without the reflection

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daniel_reetz
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Re: Scanning Plastic Books

Post by daniel_reetz » 15 Aug 2011, 21:59

You also have the option of using a polarizer on your light source and your camera. I'd say first try following Gerard's advice- give us two pictures, where the camera doesn't move but the light source does. It's possible to remove glare and other artifacts with just a little image processing.

If that doesn't work, I'll try to set up a polarization demo for you.

In fact, I'm going to say that a polarizer is probably your best and fastest option. Can you please post what camera you are using, and maybe a pic of your overall setup, so we can get you going as fast as possible?

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daniel_reetz
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Re: Scanning Plastic Books

Post by daniel_reetz » 15 Aug 2011, 22:55



I made a video and uploaded it to YT, should appear soon.

skids

Re: Scanning Plastic Books

Post by skids » 16 Aug 2011, 00:10

Sure thing. This model follows the original DIY instructable pretty well, but I don't have my cameras hooked up to monitors (I really need to do that). The camera model that I use is a set of 10MP Fujifilm Finepix S1000. The lights are 50W Halogens with diffused bulbs.
Geri_01.JPG
For Gerard:
The first image is diffused lighting bouncing off the ceiling. For some reason the glare was intensified.
DSCF5363.JPG


The second is a more direct lighting. I tried to reduce glare by aiming the lights not at the book itself, but around the book. This caused for uneven lighting, while still causing glare. :x
DSCF5361.JPG
The third image was the best of them all. The lights are aimed at the wall directly next to the book scanner. This cross-wise lighting diffused the light evenly, and was able to reduce glare somewhat. I think I'll have to experiment with this method more.
DSCF5365.JPG

skids

Re: Scanning Plastic Books

Post by skids » 16 Aug 2011, 00:22

daniel_reetz wrote:You also have the option of using a polarizer on your light source and your camera...
Simply genius BTW.

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daniel_reetz
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Re: Scanning Plastic Books

Post by daniel_reetz » 16 Aug 2011, 10:49

Here's a brief lesson on how polarization can work for you. It will be inaccurate/incorrectly said for the sake of brevity. Rather than try to explain what polarization is, I will describe how it will work.

Polarized light is light in a special configuration. If you pass it through a filter with that same configuration, it passes right through, remaining polarized. But if you rotate that filter 90 degrees, no polarized light will pass. It is all blocked.

If you try to pass unpolarized light through a polarizer, about half the light will make it through. What comes out the other side will be polarized.

So here is the neat thing about polarized light - when it strikes almost any surface, it becomes depolarized. The surface of your photograph is a good example. It is a diffuse surface that does not preserve polarization. The cool thing about that is that if you illuminate it with polarized light, the light will become depolarized (and so it will pass through a polarizing filter on the way to your camera lens). In other words, only the light that strikes diffuse surfaces will pass through the polarizer on the way back.

But.. now things get interesting. the plastic floating over the photograph does preserve polarization. So if you turn the polarizer 90 degrees to the light source, as I did in the video, you can eliminate most of that specular reflection off the plastic.

Sorry that this is not more clearly written.

OK, well, I'm attaching some images, I tried playing around w/image processing a little and didn't make much progress. The titles explain the operations, I can come back and explain more later.
SKIDS_Median_values_DSCF5365.jpg
SKIDS_difference_between_median_and_first_image_DSCF5365.jpg
SKIDS_difference_between_median_and_last_image_DSCF5365.jpg
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SKIDS_difference_between_2_and_3_subtracted_from_1_DSCF5365.jpg

the.traveller
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Re: Scanning Plastic Books

Post by the.traveller » 17 Aug 2011, 12:10

I am still curious about the warping effect occuring Skids, is the plastic covering the photo's warped?
So is there air in between?

Or is this caused by the inaccurate placing of the camera. I mean, is the camera placed in a 90 degrees angle to the album you take photographs from?

In the picture of your scanner it looks like your platten is not build in a 90 degrees angle. Rather it looks like it is 120 degrees. Therefore your cameralens has to be placed higher and in a different angle towards the album.
Cameralens perpendicular to the album in a 90 degrees angle has to be placed with an 45 degrees slope.

For calculating the exact height I have posted an Excelsheet with different calculations at
http://diybookscanner.org/forum/viewtop ... 645#p10645
See also the explanation at Fix Keystoning via hardware adjustments
Postby jay » 18 Apr 2011, 22:54

In case your cradle is 120 degrees the camera should point downwards at an angle of 30 degrees.

-----------------------------------------------------------------------------------------------
For those of us who would like to read a lamens explanation of polarisation read:
http://www.chemguide.co.uk/basicorg/iso ... rised.html

A more complicated explanation is to be found here:

http://www.upscale.utoronto.ca/PVB/Harr ... ation.html

and on the wiki page here:

http://en.wikipedia.org/wiki/Polarization_(waves)
Last edited by the.traveller on 17 Aug 2011, 13:49, edited 1 time in total.

skids

Re: Scanning Plastic Books

Post by skids » 17 Aug 2011, 13:07

the.traveller wrote:I am still curious about the warping effect occuring Skids, is the plastic covering the photo's warped?
So is there air in between?
I guess I made it sound like that was the major issue. Many of the pages do have wrinkles in the plastic covering which adds to the problem, but the overall problem is just dealing with lighting on a plastic/reflective subject. I.E. how to eliminate glare while keeping even lighting.

Thanks for the spreadsheet! I've been wondering how to do that for a long time now.
You're right about the 120 angle. I used to work for Brigham Young University in their library's Special Collections department. They had an ATIZ and another professional book scanner that both used the 120 cradle, so that's what I've always been used to. Never tried a 90 degree angle before.

UPDATE: I was perusing through the forum looking for lighting suggestions and I stumbled upon adampadsadam's book scanner and tried out his lighting set up. I took my lights and blasted them at the adjacent wall almost level with the cradle and got the results I needed.
100504_RW_P_p011.JPG
There's still a few spots of glare, but it's minimal now. I guess the lighting is at an extreme enough angle that the cameras miss the glare.

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