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04-15-2012, 06:18 AM   #1
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8 or16 bit...which is best to scan low key BW in?

I like somewhat contrasty, low key BW like this...



The negs I'm scanning can be done in 8 or 16 bit scans. So far I've been doing the scans in 8 bit, thinking they will be easier to make in the style I like.

On the other hand 16 bit may be better for not losing highlights and adding more shadow deatil. (But I am just guessing, I don't know what the difference is.)

Which is best to scan in?

Thanks

04-15-2012, 07:24 AM   #2
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Work with the most bit depth you can. The higher the bit depth, the more tones that can be defined, with 8 bit, its 256, and with 16 bit it's 65536 tones.
This might help:

Bit Depth
04-15-2012, 08:40 AM   #3
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You can always down-sample 16 bits to 8, but you cannot up-sample 8 to 16 (and expect to gain data bits), so play it safe and scan at 16. It is only disk space after all.
04-15-2012, 09:02 AM   #4
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Thanks!

04-15-2012, 09:23 AM   #5
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Yes, more bits is better bits. I think my cheap Canon scanner (which is 1000mi / 1600km away right now, so I can't check) does 24-bit TIFF scans. I always scan for the best possible resolution and color depth, whether the source is color or B&W. As mentioned, IQ can always be lost, but it can never be regained.
04-15-2012, 09:48 AM   #6
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QuoteOriginally posted by RioRico Quote
Yes, more bits is better bits. I think my cheap Canon scanner (which is 1000mi / 1600km away right now, so I can't check) does 24-bit TIFF scans. I always scan for the best possible resolution and color depth, whether the source is color or B&W. As mentioned, IQ can always be lost, but it can never be regained.
24bit comes down to 8bit per channel and that's what the previous posts goes about.
so 16bit per channel you need to use 48bit for the whole file.
Since B&W has only one channel you're talking about either 8 or 16 bit.


You want to use higher bits to prevent posterization.

www.cambridgeincolour.com/tutorials/bit-depth.htm
www.cambridgeincolour.com/tutorials/posterization.htm
04-15-2012, 11:10 AM   #7
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Even if the original is B/W, in some cases makes sense to scan it as color with 16-bit per channel for a total of 48-bits. The scanner's sensor is RGB and it will scan in color always. If you ask for B/W output, it will happen from the scanner's driver software or from the software package that came with the hardware.

There are plenty of other software, that can do a better job in combining the 3 RGB channels and generating a 16-bit B/W file. Furthermore, you will have control over how to mix, possibly help remove artifacts like color casts and selectively improve contrast.

It may be overkill for most situations, but when you want to extract every possible bit from the image that's the way.
04-15-2012, 11:24 AM   #8
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Demp you sure you get better quality by other software?
All it does is just use the luminous information, i don't see where the gain will be from using other software.

ps. we are talking about scanning a B&W photo right so you don't have the option to "mix" down the image like a coloured one.
If you're scanning a coloured photo you're right but that isn't the case now. All you need and can get is the luminous information and nothing more.

04-15-2012, 07:30 PM   #9
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QuoteOriginally posted by Anvh Quote
Demp you sure you get better quality by other software?
All it does is just use the luminous information, i don't see where the gain will be from using other software.

ps. we are talking about scanning a B&W photo right so you don't have the option to "mix" down the image like a coloured one.
If you're scanning a coloured photo you're right but that isn't the case now. All you need and can get is the luminous information and nothing more.
I was referring to a special case where there is a color cast, as in the case of yellowish paper print, or a toned print, or a stained negative, that will generate different values in the RGB channels. The scanner software will simply average the three channels. It may be advantageous to be able to manipulate the channels individually and get the best representation of a neutral gray.

As I said, this may be overkill for most situations, but it is handy in those rare instances that you want the best possible outcome.
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