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16bit vs 8bit for prints

 
 
Terry
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      02-14-2006
A photographer friend of mine processes everything in Photoshop in 16 bit
RAW. When he wants to have a print made he changes the image to an 8 bit
tif. He says that the reason for dropping to 8 bit is that most photo labs
have 8 bit printers.

It seems to me if you are going to switch to 8 bit for the print, you might
as well have never started in 16 bit in the first place. Don't you lose the
extra dynamic range, etc. as soon as you make the change? It doesn't makes
sense to me. What would happen if you sent a 16 bit file to be printed?
How much larger would the file size be - twice the size?

--
Terry
Remove the rodent from my email address to reply directly.


 
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rafe b
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      02-14-2006
On Mon, 13 Feb 2006 21:52:10 -0500, "Terry"
<(E-Mail Removed)> wrote:

>A photographer friend of mine processes everything in Photoshop in 16 bit
>RAW. When he wants to have a print made he changes the image to an 8 bit
>tif. He says that the reason for dropping to 8 bit is that most photo labs
>have 8 bit printers.
>
>It seems to me if you are going to switch to 8 bit for the print, you might
>as well have never started in 16 bit in the first place. Don't you lose the
>extra dynamic range, etc. as soon as you make the change? It doesn't makes
>sense to me. What would happen if you sent a 16 bit file to be printed?
>How much larger would the file size be - twice the size?



I doubt there are any inkjet printers that can use
16-bits and in any case, the Windows driver interface
doesn't allow 16-bit print files -- at least that's
what I've heard.

A 16 bit workflow is another matter -- easier to
defend on theoretical grounds if not from actual
observable benefits.

The idea behind the 16-bit workflow is that the
extra bits will minimize the cumulative effects
of rounding/truncation error in the course of
several radical color transformations (eg.,
curves/levels/saturation, etc.)


rafe b
www.terrapinphoto.com
 
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bmoag
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      02-14-2006
This is one of those subjects where opinion may matter more than facts.
Processing color in 16 bit yields a smoother histogram, under some
circumstances, but whether this will or can possibly improve the 8 bit
printed result, well, that may be another matter.
Under some circumstances, maybe.
The problem has to do with the limits of the ideal 8 bit color gamut, the
real limits of the printer/paper combo gamut and the limits of human visual
perception. Alas those slightly smoother 16 bit histograms are showing
gradations of color that are more subtle than what the eye/brain (not to
mention any printing process) can actually resolve. You think you are seeing
this on your monitor but your monitor and your eyeballs are, drum roll
please, 8 bit (or less) devices in terms of discernible gradations of color,
It is even worse if you work on an LCD.
Epson also points out that if you are adjusting a color in 16 bit that is
just outside or at the extreme edge of the 8 bit printer gamut you may
actually cause more difficulty accurately printing the color. One would
assume Epson's engineers know what of they write.
A similar argument applies to whether recording music with hypersonic
frequencies, essentially anything higher than 16hz, that cannot be heard by
anyone except your dog and not reproduced except by specialty speakers,
really improves the overall quality of recorded sound. Maybe, but we all
listen to iPods these days.
If 16 bits seems better to you, and you feel you get better results, then by
all means work in 16 bits.
I do it with images that are important to me but when I have experimented by
making the same adjustments in 8 bits I can't say I see any real differences
in the printed output.
My point is that it is naive to assume that 16 bits is a universally better
mode for working with images that are going to be printed because at some
point an immutable computer algorithm, totally out of your control, will
truncate your 16 bit masterpiece to 8 bits (or less) anyway.

"Terry" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>A photographer friend of mine processes everything in Photoshop in 16 bit
>RAW. When he wants to have a print made he changes the image to an 8 bit
>tif. He says that the reason for dropping to 8 bit is that most photo labs
>have 8 bit printers.
>
> It seems to me if you are going to switch to 8 bit for the print, you
> might as well have never started in 16 bit in the first place. Don't you
> lose the extra dynamic range, etc. as soon as you make the change? It
> doesn't makes sense to me. What would happen if you sent a 16 bit file to
> be printed? How much larger would the file size be - twice the size?
>
> --
> Terry
> Remove the rodent from my email address to reply directly.
>



 
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HornBlower
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      02-14-2006
16-bit is great for color and exposure adjustments, but for printing it is
100% pointless. Print drivers convert to 8-bit when you send a 16-bit image.
There are currently no 16-bit printers. Now does the printer driver do a
better job of converting the image data to 8-bit than say Photoshop? Can't
say. The chances are you will never notice a difference. So why waste time
converting to 8-bit when you print.

R


"Terry" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>A photographer friend of mine processes everything in Photoshop in 16 bit
>RAW. When he wants to have a print made he changes the image to an 8 bit
>tif. He says that the reason for dropping to 8 bit is that most photo labs
>have 8 bit printers.
>
> It seems to me if you are going to switch to 8 bit for the print, you
> might as well have never started in 16 bit in the first place. Don't you
> lose the extra dynamic range, etc. as soon as you make the change? It
> doesn't makes sense to me. What would happen if you sent a 16 bit file to
> be printed? How much larger would the file size be - twice the size?
>
> --
> Terry
> Remove the rodent from my email address to reply directly.
>



 
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Kevin McMurtrie
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Posts: n/a
 
      02-14-2006
In article <(E-Mail Removed)>,
"Terry" <(E-Mail Removed)> wrote:

> A photographer friend of mine processes everything in Photoshop in 16 bit
> RAW. When he wants to have a print made he changes the image to an 8 bit
> tif. He says that the reason for dropping to 8 bit is that most photo labs
> have 8 bit printers.
>
> It seems to me if you are going to switch to 8 bit for the print, you might
> as well have never started in 16 bit in the first place. Don't you lose the
> extra dynamic range, etc. as soon as you make the change? It doesn't makes
> sense to me. What would happen if you sent a 16 bit file to be printed?
> How much larger would the file size be - twice the size?


It's OK for a perfectly adjusted photo to be 8 bits. The problem is
that 8 bits isn't always enough for heavy image correction.

Some print labs use many more than 8 bits for internal processing but
they still take only 8 bit photos from the customer. Higher bit levels
are brutal to store and transport.
 
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Philip Homburg
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      02-14-2006
In article <(E-Mail Removed)>,
Terry <(E-Mail Removed)> wrote:
>It seems to me if you are going to switch to 8 bit for the print, you might
>as well have never started in 16 bit in the first place. Don't you lose the
>extra dynamic range, etc. as soon as you make the change?


8-bit/ch files still have a gamma of around 2.2. Paper typically has a
contrast range about 100:1.

This basically means that an 8-bit/ch file is precise enough for prints.
More bits don't really help.

8-bit/ch is just enough for a print. When an image needs lots of edits,
you need extra bits to compensate for the loss of accuracy as a result of
the editing operations. Furthermore, if you need significant changes to the
contrast of an image, you need extra bits as well, otherwise you will
get banding.

If you are essentially printing straight from the camera, you can just as
well use 8-bit/ch for the entire process.


--
That was it. Done. The faulty Monk was turned out into the desert where it
could believe what it liked, including the idea that it had been hard done
by. It was allowed to keep its horse, since horses were so cheap to make.
-- Douglas Adams in Dirk Gently's Holistic Detective Agency
 
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Andrew Haley
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      02-14-2006
Terry <(E-Mail Removed)> wrote:

> A photographer friend of mine processes everything in Photoshop in
> 16 bit RAW. When he wants to have a print made he changes the image
> to an 8 bit tif. He says that the reason for dropping to 8 bit is
> that most photo labs have 8 bit printers.


> It seems to me if you are going to switch to 8 bit for the print,
> you might as well have never started in 16 bit in the first place.


This is a very contentious topic, and there is no agreement amongst
the experts. Lat time I looked, Dan Margulis was arguing one way and
Andrew Rodney the other, and if they can't come to any agreement after
years of arguing there's no hope that you'll get any simple answers
here.

Andrew.

 
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carolyn
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      02-14-2006
the arguement for shooting in raw is to gather as much data as possible
in camera. processing it in 16-bit means that you will have lots of
data for maipulations and editing. if you were to color and dinsity
correct past a certain point in 8-bit, you will end up with combing in
the histogram which means banding and posterization in your print. i
have recently brought up the arguement that if you do most of your
edits in camera raw, why not just process into 8 bit. still, it gives
you bo wiggle room for edits in photoshop. also, i work for a magazine
doing their retouching and they have me keep EVERYTHING in 16 bit
thinking that soon the printers will catch up soon and be able to
handle 16-bit files. right now they will convert your 16-bit file into
an 8-bit file before printing. so, in my opinion, at least do your
major tonal and color correcting in 16 bit and then if you must
convert, do it now but maybe duplicate and merge visible layers and
always keep a cpoy of your large file just in case.

good luck and many good thoughts,
carolyn

www.carolyncoffey.com

 
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carolyn
Guest
Posts: n/a
 
      02-14-2006
the arguement for shooting in raw is to gather as much data as possible
in camera. processing it in 16-bit means that you will have lots of
data for maipulations and editing. if you were to color and dinsity
correct past a certain point in 8-bit, you will end up with combing in
the histogram which means banding and posterization in your print. i
have recently brought up the arguement that if you do most of your
edits in camera raw, why not just process into 8 bit. still, it gives
you bo wiggle room for edits in photoshop. also, i work for a magazine
doing their retouching and they have me keep EVERYTHING in 16 bit
thinking that soon the printers will catch up soon and be able to
handle 16-bit files. right now they will convert your 16-bit file into
an 8-bit file before printing. so, in my opinion, at least do your
major tonal and color correcting in 16 bit and then if you must
convert, do it now but maybe duplicate and merge visible layers and
always keep a cpoy of your large file just in case.

good luck and many good thoughts,
carolyn

www.carolyncoffey.com

 
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Hunt
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Posts: n/a
 
      02-14-2006
In article <(E-Mail Removed)>, http://www.velocityreviews.com/forums/(E-Mail Removed)
says...
>
>A photographer friend of mine processes everything in Photoshop in 16 bit
>RAW. When he wants to have a print made he changes the image to an 8 bit
>tif. He says that the reason for dropping to 8 bit is that most photo labs
>have 8 bit printers.
>
>It seems to me if you are going to switch to 8 bit for the print, you might
>as well have never started in 16 bit in the first place. Don't you lose the
>extra dynamic range, etc. as soon as you make the change? It doesn't makes
>sense to me. What would happen if you sent a 16 bit file to be printed?
>How much larger would the file size be - twice the size?
>
>--
>Terry
>Remove the rodent from my email address to reply directly.


If one is not going to post-process the image, especially Levels, Curves, or
Color correction, then 8-bit is fine. If you are doing work in, say Photoshop,
then 16-bit to start is the better choice, if you have it. I (almost) always
shoot RAW, Open as 16-bit and do all corrections, saving as PSD. Convert to 8
-bit and do any operations that require 8-bit (Filters mostly), then Save as
xxxxx 8-bit.PSD. Finially, I'll run Neat Image, then Sharpen, saving as xxxx
8-bit Final.PSD. Flatten and possibly convert to CMYK (depends on where the
image goes next), saving as TIF.

Hunt

 
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