Digital BW, The Print

Could someone elaborate, on the advantages of using 16 bit conversions vs 8 
bit.

My digital capture is done with a 20D in RAW (obviously). I use Raw Shooter 
to convert, I prefer it over the converter in CS2.

Thanks,

Gary


www.pbase.com/garyallenbrown

More info means better image, that sums it up.
Mark

On Aug 18, 2005, at 9:46 AM, Gary Brown wrote:

> Could someone elaborate, on the advantages of using 16 bit  
> conversions vs 8
> bit.
>
> My digital capture is done with a 20D in RAW (obviously). I use Raw  
> Shooter
> to convert, I prefer it over the converter in CS2.
>
> Thanks,
>
> Gary
>
>
> www.pbase.com/garyallenbrown
>
>
>
> Please visit the Group Homepage to check the Files, and other  
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[Non-text portions of this message have been removed]

Gary Brown wrote:
> Could someone elaborate, on the advantages of using 16 bit conversions vs 8
> bit.
> 
> My digital capture is done with a 20D in RAW (obviously). I use Raw Shooter
> to convert, I prefer it over the converter in CS2.
> 
> Thanks,
> 
> Gary
> 
> 
> www.pbase.com/garyallenbrown
> 
> 

A lot of editing will result in some discarded data, especially levels 
editing. With 8 bit, this starts to affect the image quite quickly, 
resulting in a very jagged histogram. 16 bit alleviates this issue.

Capture/edit in 16 bit, export to 8 bit for posting/printing is a good 
rule of thumb.

-Adam

If all you did was print them straight away, as is, you are unlikely to see
any difference.  The advantage comes in editing - 16 bit (actually just the
bit depth of your camera, so just 10/12bits -  I don't know what the 20D
has) will allow you considerably more editing without degradation of the
file leading to posterization and other issues.  The only downside is
storage space and memory use - both cheap.

BTW I am very surprised you don't like ACR in CS2 (it kills C1 for example)

> From: Gary Brown <baffin@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Thu, 18 Aug 2005 06:46:48 -0700
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] 8 bit vs 16 bit conversions
> 
> Could someone elaborate, on the advantages of using 16 bit conversions vs 8
> bit.
> 
> My digital capture is done with a 20D in RAW (obviously). I use Raw Shooter
> to convert, I prefer it over the converter in CS2.
> 
> Thanks,
> 
> Gary
> 
> 
> www.pbase.com/garyallenbrown

Another way to say it is that 8-bits contains just about the minimum
grayscale information needed to make a full range print.  Most
photographs initially contain much (e.g. 10 times) more contrast, so
the  digitised information should be stored with more range at least
until the stage in your workflow where the image is compressed into
the 8 bits normally adequate for printing (in camera if jpeg
compression is used, in raw converter or in subsequent image
processing if 16 bit tifs were used).  Even then having a few
bits extra allows for errors, going back to fix something etc. As far
as I have seen the only disadvantage of 16 bits is a little extra cost
for software and file storage.

Ken  


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Adam Maas
<mykroft@m...> wrote:
> Gary Brown wrote:
> > Could someone elaborate, on the advantages of using 16 bit
conversions vs 8
> > bit.
> > 
> > My digital capture is done with a 20D in RAW (obviously). I use
Raw Shooter
> > to convert, I prefer it over the converter in CS2.
> > 
> > Thanks,
> > 
> > Gary
> > 
> > 
> > www.pbase.com/garyallenbrown
> > 
> > 
> 
> A lot of editing will result in some discarded data, especially
levels 
> editing. With 8 bit, this starts to affect the image quite quickly, 
> resulting in a very jagged histogram. 16 bit alleviates this issue.
> 
> Capture/edit in 16 bit, export to 8 bit for posting/printing is a
good 

> rule of thumb.
> 
> -Adam

One of the major advantages with 16 bit images (If you
use Photoshop CS or CS2) is that you lose very little
when processing the images compared to 8 bit. Once you
have completed all processing, you can then save to an
8 bit file to reduce file size for storage.

It is an interesting experiment to process in both 8
bit and then 16 bit modes and watch the histogram for
"combing." You will immediately see the advantage of
16 bits.

Woody Spedden

--- Mark Savoia <mark@...> wrote:

> More info means better image, that sums it up.
> Mark
> 
> On Aug 18, 2005, at 9:46 AM, Gary Brown wrote:
> 
> > Could someone elaborate, on the advantages of
> using 16 bit  
> > conversions vs 8
> > bit.
> >
> > My digital capture is done with a 20D in RAW
> (obviously). I use Raw  
> > Shooter
> > to convert, I prefer it over the converter in CS2.
> >
> > Thanks,
> >
> > Gary
> >
> >
> > www.pbase.com/garyallenbrown
> >
> >
> >
> > Please visit the Group Homepage to check the
> Files, and other  
> > resources as they are often being updated.
> >
> >
>
http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
> >
> > If you wish to receive no emails or just a daily
> digest, or you  
> > wish to unsubscribe, please edit your Membership
> preferences by  
> > visiting this same page.
> >
> > Please follow these basic guidelines:
> > - As threads develop, trim off excess portions of
> earlier messages  
> > to keep them short.
> > - Good manners are required at all time. No
> personal attacks or  
> > flames. Hostile, aggressive or argumentative users
> may be removed  
> > from the membership without notice.
> > - Keep your posts and threads related to the group
> topic of digital  
> > B&W printing. Users who persistently make
> off-topic posts may be  
> > removed from the membership.
> > - By posting on this forum you agree to abide by
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> > and guidelines, and to abide by the actions and
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> > group Owner and Moderators. See \ufffdGroup Topic,
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> >
>
http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/
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> > BY PARTICIPATING IN AND/OR POSTING MESSAGES TO THE
> DIGITAL BW, THE  
> > PRINT YAHOO! GROUP YOU EXPRESSLY UNDERSTAND AND
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> DIGITAL BW, THE  
> > PRINT YAHOO GROUP.
> >
> >
> >
> >
> > SPONSORED LINKS
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> Photography school
> > Professional digital photography	Stock photography
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> > YAHOO! GROUPS LINKS
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CS2 v. C1.  What is C1?

On 8/18/05, Steve Kale <stevekale@...> wrote:

> 
> BTW I am very surprised you don't like ACR in CS2 (it kills C1 for example)
>

Phase One's Capture One software

> From: Joel Anderson <joel65203@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Thu, 18 Aug 2005 11:18:00 -0500
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] 8 bit vs 16 bit conversions
> 
> CS2 v. C1.  What is C1?
> 
> On 8/18/05, Steve Kale <stevekale@...> wrote:
> 
>> 
>> BTW I am very surprised you don't like ACR in CS2 (it kills C1 for example)
>>

One additional point that might not have been mentioned in this thread is
that when a curve is applied to a file, the resulting image often prints
smoother if the file is 16 bit at the time of application, even if the file
was 8 bit and converted to 16 bit just before the application of the curve
and even if the file is converted back to 8 bit after the application of the
curve.

Paul
www.PaulRoark.com

Cross-posting from another list:

[regarding should you use 16 bit mode]

"The simple answer would be yes.  The bit depth is
really just the amount of precision possible,
analagous to the number of decimal points in a
floating point number.  If you apply a curve to a
floating point number of say 0.12 with a factor of
1.001 and you are limited to two places output you
still have an output of 0.12.  Or, given the same
constraints, if the curve calls for a factor of 1.035
you still get an output of 0.12 (rounded from 0.124)
while if the curve applies a 1.040 factor to your
input you get a jump to 0.13 (rounding from 0.125). 
For a simple single non-agressive curve it probably
doesn't matter much, but if you do more agressive or
multiple adjustments the round off adds up fast, so
even when you start off with 8-bit image, converting
to 16-bit for adjustments buys you something.  That's
why Adobe makes such a big deal about upping its
16-bit support.

mark"
--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Gary Brown" 
<baffin@c...> wrote:
> Could someone elaborate, on the advantages of using 16 bit 
conversions vs 8 
> bit.
> 
> My digital capture is done with a 20D in RAW (obviously). I use Raw 
Shooter 

> to convert, I prefer it over the converter in CS2.
> 
> Thanks,
> 
> Gary
> 
> 
> www.pbase.com/garyallenbrown

With digital files there is less info in shadows than highlights.

A quick disclaimer before adding the following information.  I was  
trying to remember where I heard this originally but was not able  
to.  Therefore, I add the following with the warning that if you want  
more detail on this you'll have to search for it.

 From what I understand, digital image files hold far less  
information in the shadows than the higher values.  This is due to  
the nature of the digital sensor's response (scanner or camera).   
Unlike the human eye or photographic film, the sensors record data  
according to a linear model.  So in the case of a 12 bit image, there  
would be 4096 different levels of luminosity.  But this doesn't  
translate to 4096 equivalent steps.  Instead, if we use an 11 zone  
model the amount of data recorded would be as recorded below, the  
data being halved for each zone. It's sort of like photographing 2048  
light bulbs, and turning off half of them for each photo.  With film  
this would result in single zone steps, from the highest zone to the  
least.  So, for a 12 bit image the amount of data per zone is as follows

zone        levels
1                2048
2                1024
3                  512
4                  256
5                  128
6                    64
7                    32
8                    16
9                      8
10                    4
11                    2

and for an 8 bit image

zone        levels
1                128
2                  64
3                  32
4                  16
5                    8
6                    4
7                    2
8                    1
...

Obviously, with the 8 bit image, if you try to open up your shadows  
at all, they'll posterize.  Whereas the 16 bit image will have a  
greater latitude for manipulation.

Well that is about the extent of my knowledge regarding this topic.   
An additional note however, is that this is the reason that you want  
to expose for your highlights and "develop" for the shadows with  
digital, the exact opposite of how one approaches exposure with film.

Hope that helps.

Eric
www.ericashworth.net

Eric,

to add to what you said:-
most cameras and scanners do work like your first table of levels per
"zone" at the image capture stage :
> 
> zone        levels
> 1                2048
> 2                1024
> 3                  512
> 4                  256
> 5                  128
> 6                    64
> 7                    32
> 8                    16
> 9                      8
> 10                    4
> 11                    2
> 
However it would be wrong to think that a device which saves in jpeg
cannot (in principle) record below your "zone" 8 (I'll stick with your
definition).  Perhaps you were not saying it did, but someone new to
the subject could be confused.

> and for an 8 bit image
> 
> zone        levels
> 1                128
> 2                  64
> 3                  32
> 4                  16
> 5                    8
> 6                    4
> 7                    2
> 8                    1
> ...

Between the capture stage (CCD etc.) and the file save (or RAW
convert, or wherever the 8 bit file is created) there is a
"characteristic curve" applied (to use the old term which I like). 
This breaks the linear relationship between the binary numbers and the
light-level recorded on the CCD.

For example, in many point-and-shoot cameras the contrast is set so
high that they cannot even record 8 zones, only 5 or so.  While on the
other hand RAW conversion (or the few cameras with really good low
contrast settings) allows the range to be increased beyond 8 zones
(you'll find discussions about exactly how much over the previous
month or so, but no need to go there now).

Your main point is exactly correct: after the image is converted to 8
bits, any significant re-expansion of shadow contrast, or indeed any
sufficiently steep curve applied for whatever purpose, is going to
produce posterisation.  (Subtle posterisation can be visible in the 
mid-tones of black and white images.)

Ken




> 
> Obviously, with the 8 bit image, if you try to open up your shadows
 
> at all, they'll posterize.  Whereas the 16 bit image will have a  
> greater latitude for manipulation.
> 
> Well that is about the extent of my knowledge regarding this topic.
  
> An additional note however, is that this is the reason that you
want  
> to expose for your highlights and "develop" for the shadows with  
> digital, the exact opposite of how one approaches exposure with
film.

> 
> Hope that helps.
> 
> Eric
> www.ericashworth.net

I think that you have your zones reversed. In photosensitometry (and 
Adams' application of it), zone 1 represents mostly film base fog 
(nearly no exposure) thus, deepest shadow, or in your "12 bit" example, 
1 level of gray.

Thanks for sharing your analysis. It's what I have read, too other than 
the above.

Hal Gage

Absolutely correct.  Sorry, I got my numbers backwards.  In truth,  
the "zones" I delineated are more of an abstraction, as Ken  
mentioned.  Whether the actual dynamic range were 5 zones or 13, in  
the end it depends on the contrast settings as well as the in camera  
conversions or post camera processing as to how those values will be  
distributed in the final saved image.

I hope I didn't confuse anyone.

Eric
www.ericashworth.net

On Aug 19, 2005, at 10:43 AM, Hal Gage wrote:

> I think that you have your zones reversed. In photosensitometry (and
> Adams' application of it), zone 1 represents mostly film base fog
> (nearly no exposure) thus, deepest shadow, or in your "12 bit"  
> example,
> 1 level of gray.
>
> Thanks for sharing your analysis. It's what I have read, too other  
> than
> the above.
>
> Hal Gage