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

Defuse the light

All about lighting. LED, CFL, Halogen, Other? Questions and info about lighting go here.
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you1
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Defuse the light

Post by you1 » 22 Jul 2009, 18:58

Has anyone tried to defuse the light to achieve a consistent shading for the captured images?
What would be the best method/material to try it out?

Turtle
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Re: Defuse the light

Post by Turtle » 23 Jul 2009, 02:08

I've tried diffusing the lights. Here are some pitfalls:

1) Light output is reduce significantly. Either increase power or move the lights closer to the book.
2) The image sharpness is reduced. But I haven't tried photography silver padding diffusers to see if they're any better.

If you want try the look of diffuse lights, try scanning near a large tall window using the outside natural lights or scan outside. Lights from the outside actually produces sharper images. If you want the same quality as outside light you'll need photography grade compact florescent cold lights.

To diffuse the lights, you can borrow the idea from the Atiz mini and the Kirtas scanners which has two light source from the back of the scanner and one at the front (above where the user is.) see picture.
lights.jpg
lights.jpg (24.53 KiB) Viewed 11975 times

you1
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Re: Defuse the light

Post by you1 » 23 Jul 2009, 02:52

Thank you.

Daniel,
Apparently, Kirtas uses Fluorescent lighting; I recall in a posting you had advised against it, and suggest halogen for its frequency.
Do you know why Fluorescent seems to work for Kirtas?

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daniel_reetz
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Re: Defuse the light

Post by daniel_reetz » 06 Oct 2009, 23:08

I just found this video of an older Kirtas machine. Looks super labor-intensive.

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rob
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Re: Defuse the light

Post by rob » 07 Oct 2009, 16:00

I tried a diffuser, and it didn't really diffuse all that well, mainly because the lights were right up against the diffuser, and that's not how diffusers work. You have to move the lights farther away from the diffuser, and that means also moving them farther away from the book, which of course means less illumination. Or you can increase your light candlepower.

In any case, I scanned one book where there was a clear difference in illumination from one side to the other side of the page, and yet Scan Tailor fixed it on output. I continue to be impressed with Scan Tailor.
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ibr4him
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Re: Defuse the light

Post by ibr4him » 19 Jun 2011, 02:29

Turtle wrote: 2) The image sharpness is reduced. ..
lights.jpg
Not really, see this for example.

I'm using diffuser in my scanner and its working great.

P.S. Sorry to bring up the old thread, but I wanted to let everyone know that using diffusers is a great idea actually.

the.traveller
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Re: Defuse the light

Post by the.traveller » 19 Jun 2011, 03:48

ibr4him wrote: Not really, see this for example.

I'm using diffuser in my scanner and its working great.

P.S. Sorry to bring up the old thread, but I wanted to let everyone know that using diffusers is a great idea actually.
Do you have pictures of your diffuser attached to your DIY scanner?

The example showed is with an professional photography umbrella outdoors, I can't imagine you have that on your scanner.
Or are you using a professional photography kit? (I wish I had the money for it)

I can imagine however that you take pictures outside to get full advantage of sunlight, a white bedsheet will then be enough to get even lightning on all kind of books. Paperbacks but also glossy magazines.

Since summer is coming and I am going to try making my build at the end of this month it will be summer. So I will have plenty of light outside. Put up some white bedsheets for diffusion. I only have to figure out how to avoide the shadows from the columns.
The only thing I am going to use extra on the first and last picture is a Lastolite grey/white ezybalance screen. This way I will now if the light intensity has changed from the sun and adjust accordingly with Adobe Lightroom.
http://www.lastolite.us/product/0/LL%2B ... d_12%27%27
Fairly easy to tell the software that in overal the picture with the Lastolite are the correct white balance and all other pictures needs to be the same white balance. Even indoors with lower Kelvin values you can get an expectable white balance this way.

spamsickle
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Re: Defuse the light

Post by spamsickle » 19 Jun 2011, 17:46

I'd be interested in seeing your diffused light scanner too. I haven't tried it myself, but I'd think the main problem with a "white bedsheet" diffuser would be with reflections. If you're diffusing your spot light sources, but still positioning them to avoid reflections, it might make the light across a page more even. I know I'm living with hot spots on the page (or "radial gradients" at the least) with my lighting setup, but since Scan Tailor eliminates them, they're easy to live with. A good diffused lighting solution might come in handy for artbooks or textbooks with lots of pictures.

the.traveller
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Re: Defuse the light

Post by the.traveller » 14 Aug 2011, 04:39

Well summer has been a bummer. It rained most of the days and my scanner still hasn't been build. So I can't show my theory in practice.

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