Re: 16-bit vs 8-bit images
Re: 16-bit vs 8-bit images
- Subject: Re: 16-bit vs 8-bit images
- From: email@hidden (Bruce Fraser)
- Date: Tue, 12 Feb 2002 09:38:55 -0800
At 2:38 AM -0500 2/12/02, Todd Flashner wrote:
So often the bit depth conversation is discussed in absolute terms, as
though one mode is better than another, when I think the question is what
types of data, images, workflows, outputs, etc., justify the use of one mode
over the other.
Yes!
Pretty much all digital images start their life as >8 bits per
channel, and the one thing I'd be absolute about is that the big
moves need to be done in the high-bit mode, whether in the
scanner/camera software or in Photoshop. (It makes very little sense
to capture raw uncorrected 8-bit images.) So let's accept as a given
that we all do high-bit editing to some degree. The question is
really when is worth bringing all those bits into Photoshop?
The main reason I started bringing high-bit images into Photoshop was
my frustration with most scanner software's weird implementations of
color management and my disinclination to make critical decisions
based on a postage-stamp-sized preview. So, crappy capture software
is one good reason.
I mostly shoot neg film, because I'm not a very good photographer and
because I don't really like the way most chrome films distort color.
16-bit neg scans give me much greater freedom to interpret tonality
than 8-bit while eliminating the effects of the orange mask.
If you're going to repurpose images, particularly if you're going to
do compositing, 16-bit scans make it a lot easier to balance the
color of individual elements before compositing, and give you more
headroom for optimization for different output processes.
Exposed film is irreplacable, and scanning is an invasive process no
matter how careful you are. I like to make sure that I capture
everything that's on the film when I scan, so that I never have to do
it again (or maybe do it again in 15 years when I have a scanner
that's an order of magnitude better than the ones I use today). The
easiest way to do so is to pull a raw full-rez high-bit scan.
If I'm dealing with an image that I know stands a strong chance of
banding, I keep it in 16-bit all the way through CMYK conversion.
It's not a miracle remedy, but it often makes a critical difference.
If any of these reasons resonate with you, you may want to try a
high-bit workflow. It's not a religious issue for me the way it is
with some people, and ther are certainly no absolutes involved.
(Well, if you're doing a catalog of plumbing parts to be printed on
newsprint, I might go so far as to say that there's absolutely no
reason to do them in high-bit mode, but someone will probably come
along and blow me away with gorgeous liquid highlights on a 3/4=inch
elbow shot with a scanning back under HMIs...)
Most of the people I know who have adopted high-bit workflows are
photographers who have an emotional investment in the image. In a
good many production scenarios it makes little sense. I'm not
interested in proving that high-bit is "better" in either an absolute
or relative sense. I know that it's allowed me to do some things I
couldn't have done in 8-bit, but they may not be things anyone else
wanted to do.
The real bitch is that you don't know if you need high-bit until it's
too late....
Bruce
--
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