FotoDave@aol.com
Date: 05/26/00-08:10:38 AM Z
> I have not been able to achieve anywhere near 80 tones per Zone in the
> highlights.
Hi Jeff,
I didn't achieve the above using a printer but with a film recorder
(continous-tone device). With printer, especially desktop printer, it is
impossible to achieve that. Of course, we might not need that many tones per
zone though. While your original question was not on film recorder, I
mentioned it just for the discussion of how many tones are needed.
You originally asked how many zones are needed and if there was a study. Last
night before I slept I suddenly remembered where I read about it. It was
mentioned in Ctein's "Post Exposure." He was not the original researcher in
this, of course, but he mentioned about this and its application in
photography. I don't remember whether he cited the reference (I don't have
the book; I just borrowed it from the library).
One thing that is not mentioned in the book, however, is that the brain can
perceive more tones than the eye can distinguish. For example, if I show
tones with density 0.10, 0.11, 0.12 (figures are just examples) directly next
to each other, one might not see the difference, but it is a wrong conclusion
that it means we only need to record density 0.10, 0.13. Brain can *perceive*
more than eye can *detect.*
And that is how subliminal messages work. It was used quite often in
advertising in the 60s (? I forgot the exact date). Often an artwork is
superimposed with a very light images of words like sex, sex, sex, or image
of human genital, or sexy picture. The image is so light that even if told,
one still canNOT see or detect it. Yet it produces the desired result, that
is, it catches people's attention. It must be working because the practice is
later made illegal.
But back to the topic, that is why lots of tones are needed especially in the
highlight, and there needs to be even more than the number of tones that can
be visually detected.
> And if the low density areas are getting more tones
> per Zone, so much for the high areas (less than 10 tones).
That is exactly the problem, but as I mentioned in previous mail, that is the
natural, uncorrectedly response of the sensor. That is why it is better to
scan positive than negative. If we have an 8-bit scanner, just for discussion
sake, then there is nothing we can do. We cannot use the curve (prescan or
postscan won't matter if we have an 8-bit scanner) to change anything as it
will introduce posterization. If we have a 12-bit scanner, either the curve
during scanning or curve using the 12-bit data can improve a little. It is
like carrying more decimal digits and then truncate at the end but it is
still not as good as scanning positive (good separation is in the low density
area where in positive is the highlight but in negative is the shadow).
One thing you can check for yourself is if you turn off all correction (no
curve, no gamma, no nothing) in your scanner and scan a step tablet
(reflective or transmissive) and check the rgb figures in the high density
and in the low density. I believe it will convince you that scanning negative
can cause some trouble (of course the trouble/problem might not present in
every image depending on how much the highlight/shadow are).
> I can reduce the maximum ink density on the base negative so that the
> 256 tones (black ink) are distributed only from Zones I through V (about
> 51 tones per Zone average) (about 20 tones are generated with yellow ink
> to provide a threshold and Zone 0), and add a 4 Zone mask for Zones VI
> through IX (64 tones per Zone average), and another mask for X through
> XII (about 85 tones per Zone average). I can likely print these on
> cleared Kodalith 2556 film (not tried yet) which should be thin enough
> to keep a sharp image. This is my current plan.
Yes, this is in a sense a multitone printing except that you are not multiple
printing your final result but you are multiple-printing your negative.
> Oh no, NOT SO, back to Physics 101.
> Light is electromagnetic radiation, transverse waves (^v^v^v^v).
> Sound is NOT E-M radiation, but is compression waves (|| | | |||).
I did feel something strange when I said sound is electromagnetic waves but
it has been a while since my Phsyics 101 days. I stand corrected. So they are
all waves.
The point that I was trying to say, however, was ....
> Music also presents in space as when several instruments are combined as
> in an orchestra, producing a sound quite different from the individual
> instruments.
<snip>
> Photographic presentation in time is called movies (film, etc.).
that it is beautiful that all these work in a beautiful, harmonious, and *so
similar* manner!
Dave Soemarko
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