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Don
Guest
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 Posted:
Sun Nov 06, 2005 5:26 pm Post subject:
Re: An approach for n-bit int. / m-bit ext. scanners (was: R |
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On Sat, 05 Nov 2005 16:14:57 +0100, "Lorenzo J. Lucchini"
<ljlbox@tiscali.it> wrote:
| Quote: | Anyway, I thought you were tired of this?
Ok, you're really being captious on purpose now. Sorry, I just can't avoid
thinking that.
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Language barrier.
I was quite serious. There was nothing behind that question. You said
you were tired of this. I agreed. And then you continue...?
So I just posed the obvious question.
Anyway, can we agree to disagree agreeably, now?
Don. |
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Lorenzo J. Lucchini
Guest
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| Posted:
Sun Nov 06, 2005 8:19 pm Post subject:
Re: An approach for n-bit int. / m-bit ext. scanners (was: R |
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Don wrote:
| Quote: | On Sat, 05 Nov 2005 16:14:57 +0100, "Lorenzo J. Lucchini"
ljlbox@tiscali.it> wrote:
Anyway, I thought you were tired of this?
Ok, you're really being captious on purpose now. Sorry, I just can't avoid
thinking that.
Language barrier.
I was quite serious. There was nothing behind that question. You said
you were tired of this. I agreed. And then you continue...?
So I just posed the obvious question.
Anyway, can we agree to disagree agreeably, now?
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It wasn't about that specific question.
Repeat: on the topics we've been talking about, I've already agreed to
disagree agreeably.
I simply thought: well, why not try to agree at least on something similar
and related to the original topic, but simpler and less problematic (so
that it'll probably be easier to agree on)?
Indeed, you did agree on it, but immediately started attacking on the ground
that it had "nothing to do" with the previous topic, and that I was
"contradicting myself again", and so on.
I think that, in reality, you know perfectly that both things are not true:
it is similar and related to, though not the same thing as, the previous
topic, and as such, my statements were not contradictory.
Repeat again (and please take note of this paragraph): it's still a matter
of doing in-scanner whitepoint adjustment to obtain information from the
"latent" 2 bits of the OP's scanner -- and in this respect, it's very
related to the original topic --, but this time, there are no "preview
keyhole" issues involved -- and in this respect, it's different from the
original topic, and probably easier to agree on.
Pretending to not understand this simple concept, and starting to attack me
again instead of just saying something like "yes, now that's right, this
more limited but safer approach would be good to use on the OP's scanner,
and contrary to your previous suggestions, I have no technical objections
to it", is what I call captious.
by LjL
ljlbox@tiscali.it |
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blumesan
Guest
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| Posted:
Wed Nov 09, 2005 8:26 am Post subject:
Re: An approach for n-bit int. / m-bit ext. scanners (was: R |
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Lorenzo J. Lucchini wrote:
| Quote: | Listen, will you concede that the OP should, at least, measure the color of
the film base (that's easy to measure, you can take as many samples as you
like, as it only needs to be done once for an entire roll of film), and
then use that color as whitepoint in the scanner?
It just doesn't make any sense to waste bit depth for values above the
orange mask's color, and there are no "preview keyhole" issues here.
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It is with great tripidation that I enter this thread. I have nothing
to contribute to the basic subject (or non-subject) of the prior
discussion. I do have a simple question regarding the above quote:
Would not this procedure make sense also for scanners where input bits
= output bits?
Thanks,
Mike |
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Lorenzo J. Lucchini
Guest
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| Posted:
Wed Nov 09, 2005 8:09 pm Post subject:
Re: An approach for n-bit int. / m-bit ext. scanners (was: R |
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blumesan wrote:
| Quote: |
Lorenzo J. Lucchini wrote:
Listen, will you concede that the OP should, at least, measure the color
of the film base (that's easy to measure, you can take as many samples as
you like, as it only needs to be done once for an entire roll of film),
and then use that color as whitepoint in the scanner?
It just doesn't make any sense to waste bit depth for values above the
orange mask's color, and there are no "preview keyhole" issues here.
It is with great tripidation that I enter this thread. I have nothing
to contribute to the basic subject (or non-subject) of the prior
discussion. I do have a simple question regarding the above quote:
Would not this procedure make sense also for scanners where input bits
= output bits?
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Not much.
It wouldn't because, in such a scanner, you can obtain exactly the same
result (or a better result, as you have some more control) in
post-processing. You don't need to do it in the scanner's firmware or
driver, as there are no bits to lose.
Anyway, note that I was actually intending this as a way *to maximize bit
depth* (on an appropriate scanner), not to remove the orange mask.
In my view, the fact that it also results in removing the orange mask is a
side-effect that can be eliminated later, if desired -- though I suppose
that for most people it would be a *desired* side-effect, and as such there
would be no reason to eliminate it.
Let me put it into another way: imagine that you have a 16bpc image, and
that you want to convert it to 8bpc, but retain as much information as
possible.
What could you do?
Well, you could output a *normalized* 8bpc image, where all values from 0 to
255 have some information. If the original image was already normalized,
you won't gain anything, but if it wasn't, you would.
This is similar to what I was suggesting.
But, this way, you will obviously falsify the correct image colors. What can
you do to avoid it? Well, you can *also* save somewhere the original
whitepoint and blackpoint values.
So, in the end, you will have an 8bpc image *plus* a file containing
something like "Whitepoint Rnnn Gnnn Bnnn, Blackpoint Rnnn Gnnn Bnnn".
Using these two files, you will always be able to get back the original
colors, if desired -- and this is similar to orange mask removal in my
example.
The point is that bit-depth maximization and orange-mask removal (or, in
general, whitepoint adjustment) are conceptually two different things, even
though they may both be obtained by the same process in practice.
by LjL
ljlbox@tiscali.it |
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