Re: 16 bit versus 8bit
Re: 16 bit versus 8bit
- Subject: Re: 16 bit versus 8bit
- From: email@hidden (Bruce Fraser)
- Date: Wed, 6 Feb 2002 17:58:21 -0800
At 4:00 PM -0800 2/6/02, Lee Varis wrote:
If I understand you here (and I may not fully) this just points out that
the 16 bit histogram is just an optimized 8 bit histogram and I'm still
not sure that that is particularly useful except to demonstrate the
advantages of 16 bit over 8 bit in some "visible" way (it makes a good
screenshot for a book). Anyone else have some method or technique that
utilizes the info in the histogram?
It's a histogram, no more or less useful than the one you get with an
8-bit file. I have some esoteric image-analysis techniques that
involve doing things with histograms for automated corrections, but
they're nothing that wouldn't work better if a human was looking at
the image instead. Basically, they're good for telling you whether
your highlights or shadows are clipped, whether you have totally
saturated one or more channels, and in a much less exact way whether
or not you can afford that big contrast tweak you want.
16-bit masks would be handy on 8-bit channels, yes. I thought you
were talking about applying masks in 16-bit files -- you can only do
one of those at a time so they don't typically interfere. Working in
high-bit, I haven't really run into a situation where I needed a
16-bit mask, but of course that doesn't mean that they wouldn't be
useful if we had them!
I use a bunch of scanners though the Imacon is my workhorse, but most
drum scanners nowadays can be persuaded to deliver high-bit files --
Don Hutcheson's site is full of useful info on the various flaming
hoops tha have to be negotiated.
As to archiving high-bit files, storage is so cheap that I just don't
see a reason not to. A few times I've gone back to images to make
composites, and I've had to make fairly major tweaks to the color
balance that I'm not sure would have been successful with 8 bits.
There's also the issue that in the future we may be able to do much
more than we can today. I scan the film once, then put it in
long-term cold dark storage. If I ever get a scanner that's an order
of magnitude better than the ones I have now, I may rescan, but until
then I know I don't have to.
But it's not a religious issue for me. I've seen lots of great work
done with 8-bit imagery. I just need all the help I can get!
Bruce
--
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