D
Don
You can't have it both ways. If it would mess up automatic colorcorrection then it's not a solution.
Don.
You can't have it both ways. If it would mess up automatic colorcorrection then it's not a solution.
Don.
D
Don
The weird histogram stuff (gamma correction, "the waves") is at the
shadow side of the histogram. In this case, we are interested in the
highlights to see how far the dynamic range stretches and those parts
are very well defined in the histogram and clearly show there isn't
enough range, especially in the red.
No, he's not. He's been very evasive and contradictory. He keeps
moving the goal posts and I keep submitting everything asked of me.
And every time he's cornered he just goes silent.
Individual Analog Gain is an essential tool. To make a blanket
statement it's not needed is just patently and self-evidently wrong,
and it's impossible to defend such a statement. That's the quagmire.
Don.
D
Don
That's not a problem, nor am I ever likely to...
Oh, so unregistered versions can't produce raw files?
Well, that may explain the vociferous insistence on raw files, then,
knowing quite well they can't be supplied - after I supplied
everything else demanded of me.
If true, then it appears like another evasive maneuver to avoid
admitting that individual Analog Gain is an essential tool.
Don.
E
Ed Hamrick
Don said:
I'd be happy to give you a free license - I actually want to
get to the bottom of this. Just e-mail me and I'll e-mail it
back to you.
Regards,
Ed Hamrick
B
Bart van der Wolf
Don said:
Sorry Don, that's not true, but I do understand how frustration can cloud
one's judgement. What he has said makes sense, and it is also usually better
to solve the problem itself rather than attacking the symptoms. There must
be some reason that your Red channel is so far underexposed, and it seems
unlikely (TBD) that a dye/sensor mismatch is the only cause. Besides, the
real issue you have presented is more about colorbalancing (blue appearance
of dark Kodachromes). There is a difference, so read along.
That's not fair, because he really is looking for a solution by excluding
potential causes. For that he needs Raw scanner data, which has not
materialized AFAIK. He apparently even offered you a free licence, but you
may not have been aware at the time of writing down your frustration.
What Ed has been trying, sofar unsuccessfully it seems, to explain is that
colorbalancing is not the same as optimizing the signal-to-noise ratio of a
scan. He is absolutely right. Your basic problem is a colorbalancing one,
e.g. trying to get snow look like snow (given a dark Kodachrome slide and a
scanner with limited dynamic range). That may be difficult when too much
data is lacking, but what I've seen sofar indicates other problems. Raw data
is needed to better analyse the cause.
I do agree that for some specialized uses (and 99.8% of the people would
create more issues than solve them if used wrong) an individal channel
exposure control is beneficial (to improve S/N ratio). The downside is that
for most people it screws up colormanagement, which is related to (but not
the same as) colorbalancing. So maybe an advanced-advanced user option (not
saveable in the ini file) with a warning pop-up (Beyond this point, you are
on your own! Continue, Abort?) could be considered.
Bart
B
Bart van der Wolf
SNIP
Apparently you are right, good catch.
Bart
Apparently you are right, good catch.
Bart
D
Don
My sentiments exactly!
That's how this whole thing got started. In spite of its many
shortcomings, NikonScan can at least be "tamed" so it does exactly
what you tell it to.
Although, there are gotchas. For example (at least in my setup)
restarting NikonScan after turning off Nikon Color Management is not
enough. One needs to power down the scanner as well as there seem to
be "leftovers" in the scanner's internal RAM which are not
re-initialized.
Precisely. The need for this most elementary and essential requirement
is how all this got started.
I just instinctively distrust software which "knows better" and forces
me into a straightjacket.
Don.
D
Don
OK, will do!
Don.
D
Don
He just did.
Glad to hear it!
Don.
D
Dan
Ed Hamrick said:
Ed,
Would you like me to post a raw scan of the troublesome Kodachrome on
my website for dl?
I did have limited success, but only with Nikon scan and only with ROC
enabled. Without ROC, I get an absolutely flat, dark (blocked up) scan
from this very dark original. Even with ROC enabled, I can't get a
"good" scan from this dark image (I have about 15 or 20 that were
underexposed). I had no luck at all using Vuescan on these slides --
only Nikon scan was able to give me something marginal. It's still
frustrating that I can get the preview to look so good, but still
can't get a good scan. I had pretty much given up and started looking
for a lensboard for my Illumatron so I can simply make internegatives
of these particular images.
One thing I've wondered about -- there used to be a product available
(a chemical bath) that could lighten underexposed Kodachromes, but it
only worked on certain types of Kodachrome. Seems there was a
fundamental change in Kodachrome's emulsion around the late 70's.
Could that be why some people are having no problem with old, dark
Kodachromes, while others can't get a decent scan.
Also, normally exposed slides from the same batch aren't a problem --
only those that were heavily (1+ stop) underexposed.
Dan
B
Bart van der Wolf
SNIP
Don, see my other post about it but, the channel exposure is for controlling
Signal to Noise, not colorbalancing. Different exposure levels lead to
different saturation limits.
Bart
correction then it's not a solution.
Don, see my other post about it but, the channel exposure is for controlling
Signal to Noise, not colorbalancing. Different exposure levels lead to
different saturation limits.
Bart
E
Ed Hamrick
Don said:
I haven't gotten the e-mail yet. Could you remind me in the
e-mail that this is a free license for diagnosing the LS-30
CCD exposure problem? I don't know your real e-mail address
to keep an eye out for.
Thanks,
Ed Hamrick
P
Philip Homburg
I think that automatic exposure information is kept around. Pressing the
auto-exposure button at a frame that covers a large density range may have
the same effect.
Except that I don't know how a scan of a slide is supposed to benefit if
there is any white in the slide.
Different analog gain settings may help for layers in a slide that don't
reach Dmin. However, white snow sounds like a situation where the
minimum density is equal for all channels.
Quite right.
M
Mike Engles
Dan said:
Hello
Try just outputting 8 bits from the scanner in Nikonscan.
Does the scan then match the preview?
Mike Engles
D
Dan
Mike Engles said:
No. Doesn't match under any circumstance for the dark slides. For
other slides, no problem, either with Vuescan or Nikon scan. Tried as
many combinations as I could.
Dan
D
Don
As it applies to me, I will strongly take issue with that. I have
substantiated all my statements with facts and remained objective
throughout. But I will not let illogical statements go unchallenged
either.
According to Kennedy, as you must remember, that's exactly the reason
(LED spectral characteristics). BTW, where *is* Kennedy? ;-)
One can't claim that implementing separate Analog Gain is at the same
time both "trivial" and "difficult". One can't claim that dark, blue
scans are "the default color balance" and then deny it. Etc... Etc...
Now, that's not fair. So, when faced with it all I do is respond
accordingly.
I never claimed it was the same thing! Check the thread. It's another
attempt at evading the issue by attributing something to me I have
never said and so change the subject.
However, you can't deny that an image with a wider dynamic range and a
better S/N ratio is easier to color balance (there is more to work
with) than the one with a narrower dynamic range. Don't you agree?
If you do then anything which contributes to a wider dynamic range and
a better S/N ratio is a "Good Thing". Correct? Well, adjusting
individual Analog Gain contributes to a wider dynamic range and
improves the S/N ratio.
I firmly believe it's always better to give the user more control
rather than less. Sure, make it as easy as possible by automating,
etc. but always give an "opt out" clause.
And I just fail to see how adjusting individual Analog Gain can
negatively effect the algorithm.
The only thing the algorithm needs to know is where is the neutral
point (I supply quotes stating this). It doesn't have to know whether
the slide is a Kodachrome, or not. Ed even said that the Kodachrome
option is totally unnecessary and he was thinking of removing it
altogether (remember, you begged him not to).
If that is the case, then as far as the algorithm is concerned a
Kodachrome with a boosted red is indistinguishable from a
non-Kodachrome where such a boost is unnecessary.
Don.
D
Don
I sent it to "(e-mail address removed)" with the subject line "Analog Gain
saga...".
If you can't find it, it's the same temporary account I set up for the
images I posted:
tempdon100164833 (at) aol.com
Thanks,
Don.
D
Don
I never said it was about color balancing! (Please re-check the
thread.) The sole purpose of individual Analog Gain adjustment is to
improve dynamic range of channels which my scanner doesn't scan
correctly.
Don.
D
Don
I haven't really narrowed it down because I have Nikon Color
Management (NCM) off permanently.
In any case, for those who do use NCM I'd imagine it's a really
annoying bug considering Nikon makes the user even restart the program
and yet Nikon couldn't be bothered to warm-start the scanner.
Actually I've been using white highlights to detect where my scanner
fails and then adjust Analog Gain (AG) until I recover dynamic range
(see below for more).
I'm not entirely happy with this because I would prefer an objective
method. I still believe Nikon should have provided the values needed
for this adjustment but those in-the-know around these parts tell me
that's impossible.
I'm still not convinced and I'm now close to figuring out the formula
(as a function of exposure) to get at the ratio of distortion
empirically and then correct it i.e. in my case that means how much I
need to cut blue and boost red to correct Nikon's distortions.
The way I go about it is to examine the histogram of the area in
question. This exposes the inadequacies of the scanner as individual
channel don't reach 255 e.g. R=120, G=130, B=250. I then adjust AG to
stretch R & G until they also approach 250 or thereabouts. After that
I have enough dynamic range across the board to color balance and do
other editing without causing banding or other artifacts.
Don.
M
Mike Engles
Dan said:
Hello
I had a similar problem.
I then tried the tryout of Silverfast. This was OK
I then went back to Nikonscan and found the trouble I was having had
pretty well gone away. I just wondered if using Silverfast had somehow
'reset'the scanner. It sounds silly, but I feel something like that has
happened. I noticed a similar thing a few years back after I had my LS30
checked by Nikon.
My LS50 scans of Kodachromes, even using extreme settings for dark
slides are pretty well OK. The preview does not exactly match the scan
in terms of contrast or exposure, but the heavy contrasty shift to
purple has gone.
Mike Engles