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

light washes out text AND noise in photoshop not in ST

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o3h1p
Posts: 71
Joined: 08 Nov 2010, 22:47

light washes out text AND noise in photoshop not in ST

Post by o3h1p » 29 Feb 2012, 15:02

PROBLEM #1: Light washes out text.

I am using the standard setup build:

http://www.diybookscanner.org/forum/vie ... ?f=1&t=333

with cheap clamp lamps not too different than those shown in the picture (but not the same).

The lights are so bright that it washes out the text. This is not due to a reflection from the platen (at least Im' pretty sure it's not).

Photo:
2-29-2012 1-31-03 PM.jpg
Photo
2-29-2012 1-31-03 PM.jpg (51.48 KiB) Viewed 6672 times
In ScanTailor:
2-29-2012 1-33-19 PM.jpg
washed out
2-29-2012 1-33-19 PM.jpg (113.98 KiB) Viewed 6672 times
I set my camera to shutterspeed 1/30; fstop 4.0; iso 80. Has anyone else experienced this? With so much light, would it be better for me to set a faster shutter speed?

PROBLEM #2: Noise seen in photoshop that I don't see in scantailor

AT the output screen in ST:
2-29-2012 1-39-23 PM.jpg
in scantailor
2-29-2012 1-39-23 PM.jpg (120.68 KiB) Viewed 6672 times
In Photoshop (or any photoviewer):
2-29-2012 1-39-49 PM.jpg
in photoviewer or photoshop
2-29-2012 1-39-49 PM.jpg (87.33 KiB) Viewed 6672 times
A few questions:

1) Why this difference, why doesn't ST show this noise (both are on the same monitor btw)?
2) Why am I getting this noise? Is there a setting on my camera I can use to stop this?

It's almost worth it to me to just take a screencap of the better looking ST output screen than try an assemble a file from the output that ST creates. But that seems really silly, why can't ST just save the file that it displays without the noise?

Thanks!
jack

Anonymous2
Posts: 97
Joined: 18 Oct 2011, 16:05

Re: light washes out text AND noise in photoshop not in ST

Post by Anonymous2 » 29 Feb 2012, 15:30

Make your f-stop higher or increase the shutter speed, as your picture is way too bright. The larger the f-stop, the smaller the aperture and the less light gets into the camera. Also, angle your lights so that they aren't visible in the reflections.

As for the noise, that cyan/blue looks like a color space issue. How are you importing the JPEG into Photoshop?

o3h1p
Posts: 71
Joined: 08 Nov 2010, 22:47

Re: light washes out text AND noise in photoshop not in ST

Post by o3h1p » 29 Feb 2012, 16:04

Thanks for your reply:

* Do you have a recommendation for the fstop/speed? Would be going as fast as 1/200 be ok?
* With the standard setup there doesn't appear to be any orientation in which I don't have some reflection on the platen. The question is whether it is directly in the text area. I might have to discuss this aspect in the thread for this build.
* I am importing them as tiffs that ST produces not as jpegs.

o3h1p
Posts: 71
Joined: 08 Nov 2010, 22:47

Re: light washes out text AND noise in photoshop not in ST

Post by o3h1p » 29 Feb 2012, 16:05

Also I should note that this isn't really a photoshop issue. If I view the tiff from the windows photoviewr the same noise is seen. It's just strange that this noise isn't seen in the ST output window.

Anonymous2
Posts: 97
Joined: 18 Oct 2011, 16:05

Re: light washes out text AND noise in photoshop not in ST

Post by Anonymous2 » 29 Feb 2012, 16:09

I usually go for 1/60th of a second, as the high-ISO exposures get noisy.

As for the images, could you upload a sample of the input and output images to a file hosting site? I've never seen a problem like this before.

o3h1p
Posts: 71
Joined: 08 Nov 2010, 22:47

Re: light washes out text AND noise in photoshop not in ST

Post by o3h1p » 29 Feb 2012, 17:15

I have my iso at 80. What Iso do you use when you're at 1/60?

Here are the files:

http://www.mediafire.com/?92xje8k9ipaz2 ... dphn4jl2sq

o3h1p
Posts: 71
Joined: 08 Nov 2010, 22:47

Re: light washes out text AND noise in photoshop not in ST

Post by o3h1p » 29 Feb 2012, 18:54

If you do find a solution Anonymous, please let me know. Using 'levels' in photoshop to compensate for this noise certainly isn't the best way to deal with it.

Anonymous2
Posts: 97
Joined: 18 Oct 2011, 16:05

Re: light washes out text AND noise in photoshop not in ST

Post by Anonymous2 » 29 Feb 2012, 18:55

I use a single 18 MP Canon D-SLR and I can get away with higher ISOs without much quality degradation. Point-and-shoot cameras have smaller sensors and are affected more by high-ISO noise, so try keeping your ISO below 800. Mine is usually at 200-400 ISO, but my sensor size is different than yours, so it probably looks the same as your 80 ISO.

As for the image problem, I can't reproduce it. I've also attached a PDF version of the image. Does it have the same problem?
Attachments
IMG_7059.pdf
Resulting PDF
(292.35 KiB) Downloaded 237 times
IMG_7059after.tif_045.png
Screenshot
IMG_7059after.tif_045.png (571.01 KiB) Viewed 6658 times

Tulon
Posts: 687
Joined: 03 Oct 2009, 06:13
Number of books owned: 0
Location: London, UK
Contact:

Re: light washes out text AND noise in photoshop not in ST

Post by Tulon » 29 Feb 2012, 19:48

It looks like Photoshop / built in Windows image viewer apply gamma correction "to enable you to see the fine details you wouldn't otherwise see". Programs not targeted at photos typically don't do that.
Scan Tailor experimental doesn't output 96 DPI images. It's just what your software shows when DPI information is missing. Usually what you get is input DPI times the resolution enhancement factor.

o3h1p
Posts: 71
Joined: 08 Nov 2010, 22:47

Re: light washes out text AND noise in photoshop not in ST

Post by o3h1p » 29 Feb 2012, 19:51

Thank you very much for helping me.

I took your pdf, extratracted the page as a tiff and wrote on it to show you what I'm seeing.

I'm seeing a lung diagram on the left that i see on page 218, so maybe this was a reflection from the other side of the scanner?
I'm seeing a faint hint of a diagram from 220. If you have a laptop you can bend the lcd down to see it more clearly or look at your monitor at a shallow angle.

As far as the degree that I see these things.

* If I look at the tiff you posted on the forum, I can barely see anything.
* The pdf you sent me has some noticeable 'noise'
* If I convert the 7059 tiff output to pdf I get a pdf basically the same as yours with the same amount of noise.
* If I view 7059.tiff in windows photo viewer I see the noise
* If I view 7059.tiff in photoshop I see the noise
* If I view 7059.tiff in IFRANVIEW I DON'T see the noise. (Note, I do see a very faint shadow of these images, but nothing like I see in the photoviewer/acrobat/photoshop.)
* If I view 7059.tiff on a laptop, I do not see this noise, but if I bend the lcd I definitely see it there.

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