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Old 07-08-2006, 11:27 AM   #1
dejavu_01
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Does Linux support 32bit color scanning?


Hello

I bought a Cannon flatbed scanner that sane-project indicates compatible with linux. The scanner is intended for old photo achiving which I would like to scan at the optimal color depth - 32 bit. I'm wondering that Linux would support scanning at said color since what I see in KDE display setting and xorg config, it can go as high as 24bit, so does scanning in Linux be effected by 24bit limitation? Forgive my ignorance. If the limitation exists, I'll just do it in Windows. Thanks

Last edited by dejavu_01; 07-08-2006 at 11:29 AM.
 
Old 07-08-2006, 11:43 AM   #2
ethics
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linux only does 24 bit, 32 bit is only 24 bit with the alpha layer for fancy things/transparency etc i think.

Give it a shot and compare the 2, i doubt there'll be a difference
 
Old 07-08-2006, 01:47 PM   #3
jschiwal
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The color depth of a scan may mean something different than the color depth on a video card. On a video card a 24 bit color depth means that each color has 8 bits. A 32 bit color depth on a video card has 8 bits/pixel for each color and an 8 bit transparency bit. Since 32 bits is not divisable by 3, I don't know what 32 bits means for a scanner. You will probably need to read more about how the scanner represents color and how the filesystem the scan records it in can represent an image.

I don't remember who said that the great thing about standards is that there are so many of them. But this is the case in the large number of color encoding schemes that exists. The devil is in the details. What encoding schemes are supported by your scanner; by the filetype you are using to record the image. Does the Gimp support that filetype and encoding schemes? Does the filetype support different encoding schemes, and if so which ones? The specifications on the scanner may provide more details.

A weakness in computer displays is the low resolution of black and white information that can be displayed. A 24 bit display will only display 256 levels between black and white on a black and white picture. rgb=000, rgb=111, ... rgb=777. The scanner may use an encoding scheme that improves on this. It's possible that the chroma information contains fewer than 8 bits per pixel and the extra information is used for alpha information.

Here is one that might really get your head spinning. We were taught in school that there are 3 primary colors, and that all other colors are formed from them. Actually, for humans, the receptors in our eyes respond to 3 color frequencies in an infinite spectrum. When broken up by a prism, these colors appear the strongest because that is what we can detect. So this business of color encoding even exists in our brains!

Last edited by jschiwal; 07-11-2006 at 05:48 AM.
 
Old 07-09-2006, 12:05 PM   #4
Dummy-in-Linux
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Talking about the best why not going for a Visual treat of brilliant 48-bit colour depth. My Epson does is all http://www.epson.com.sg/products/sca...90_Photo.shtml
 
Old 07-09-2006, 12:34 PM   #5
cs-cam
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Before people jump on that sweepingly unsupported statement (bad move sport, backup your comments) feel free to find out mroe. Found the link as I was curious myself..
 
Old 07-10-2006, 02:31 AM   #6
Dummy-in-Linux
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Nice website, but it almost if I read old stuff.

36-bit color images have 3 color channels of 12 bits each - one channel each for red, green and blue. When combined, the red, green and blue channels provide up to more than 1 billion colors.

The 8 extra bit on a "professional" 48 bit color scanner do little more then shade some none color information. Similar to the 8 bit on a 32-bit color scanner, if it a professional scanner.

The cheap color scanners you probably refer are the stuff you by at the local supermarket.

You have right that it is not easy to export a scanned picture with a higher color depth as 24 bit, but then "professional" software helps you to remind that only some software support this. Adobe Photoshop CS2 is one of the only software that is on sale which can do it. Still look for a Linux program.

And even if I not able to export my scan better then 24 bit, I still belief the picture looks better then if I scan it with a lower color depth.

Of course all this information, I get from manufacturers who want to sell stuff. But if it is not true it is probably the biggest conspiracy ever.
 
Old 07-11-2006, 06:14 AM   #7
jschiwal
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You may find this sample chapter from Margulis interesting: http://www.ledet.com/margulis/PP7_Ch15_Resolution.pdf

Quote:
If a scanner can’t see
detail in shadow areas, more BPC won’t help.
We may have 4,096 VOT, but in this case,
VOT stands for varieties of trash.
Also, in photoshop, you may not have full functionality working with 48 bit images.
 
Old 07-11-2006, 11:59 AM   #8
Dummy-in-Linux
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I agree their is no difference between a US$ 30 scanner and professional scanners of plus US$ 1000, it is all a lie, and this conspiracy which include all digital media manufacturers in the world is even bigger than the one around Nixon.

Websites who say that 48 is 24 or 36 is 32 or say 4 thousand shades of trash, are there enough...same as that I can find thousands of websites who say Elvis is still alive....or Aliens visited the family BBQ....

Last edited by Dummy-in-Linux; 07-11-2006 at 12:01 PM.
 
Old 07-11-2006, 02:59 PM   #9
KimVette
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Quote:
Originally Posted by Dummy-in-Linux
I agree their is no difference between a US$ 30 scanner and professional scanners of plus US$ 1000, it is all a lie, and this conspiracy which include all digital media manufacturers in the world is even bigger than the one around Nixon.
Either you have a crappy monitor, bad eyes, or have never worked with a high end scanner or camera (edit: based your judgement on extremely bad source media where the best drum scanner in the world won't see more detail than the WalMart model /edit). There is a world of difference between $30 scanners and professional models, even if you compare 24 bit to 24bit scanners rather than 24 bit to 48 bit scanners.

Last edited by KimVette; 07-11-2006 at 03:01 PM.
 
Old 07-12-2006, 10:32 AM   #10
Dummy-in-Linux
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Kimvette,

Of course there is a difference in quality between low cost and professional scanner, when I say “it is all a lie” I was joke.

Or do you claim that Elvis is still alive and/or Aliens come to you family BBQ?
 
  


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