Re: green-yellow
FWIW, it is very instructive to print out the QTR ink limits test and
graph the UV transmission density versus ink percentage for each ink
on a single graph. When I did this for my printers, the 'aha' moment
came when I realized that certain combinations of ink colors are going
to be more prone to the graininess effect that is sometimes observed
in the highlight areas of prints. In particular, the green color that
I used for a long time combines two colors that are very far apart in
terms of UV transmission density at a given density: i.e. the yellow
and cyan inks. When I constructed profiles using only ink combinations
that are close in terms of UV transmission density, I got some of the
smoothest highlight transitions ever.
Clay
On Apr 9, 2009, at 9:25 AM, Loris Medici wrote:
I didn't realize that the Green/Blue transparency was the negative
of the
Magenta/Yellow transparency. So yes, that's blue not Cyan, thanks
for the
clarification.
On the other hand my question still holds -> because it was asked in
terms
of printer inks -> not screen colors. If you see Blue on screen you're
actually printing Cyan+Magenta in the printer, so on, so on...
S:Y->P:Y, S:M->P:M,
S:G->P:Y+C, S:B->P:M+C
(S: Screen color/P: Printer inks used to print the color on the
screen)
When above is analyzed, it can be seen that Cyan is definitely more
opaque
for UV light than Magenta is... (Magenta patch is darker than Blue
patch!)
For me, 3 different printers / 3 different inksets and Yellow was
always
the most opaque/dense color. (Against Green and others.)
Thanks for the long answer.
Regards,
Loris.
9 Nisan 2009, Perşembe, 4:46 pm tarihinde, Christina Z. Anderson
yazmış:
Hi Loris,
The colored left of the image, the entire thing, is the "negative"
printed
on Pictorico (and the blue/green portion of that "negative" is the
inversion
of the yellow/magenta). The right side of the image is a pt/pd
print from
that negative. So yes, the pt/pd is completely all done at the
same time
same everything.
Why yellow is so dense in general and yet so pale, Mark Nelson or Dan
Burkholder could answer these questions much better than I, but my
guess
is
that it is because it is opposite the UV spectrum. I'll bring my
dots
into
the BW darkroom this weekend and get another visual in a new process.
Why green holds back more light than pure yellow--again, Mark
Nelson or
Dan
Burkholder can weigh in here? My GUESS would be:
1. more actual ink of cyan and yellow is laid down to get an even
color
green?
2. the green color blocks out some other wavelength?
3. the process of choice is less sensitive to a particular
wavelength?
But one thing that may be the cause of the confusion--the colored dot
example has pure magenta and yellow up top (magenta being
R255B0G255 and
yellow being R255G255B0) which I MIGHT ASSUME (and here I am
getting into
dangerous territory) is the printer laying down magenta ink only and
yellow
ink only--no mix. I ASSUME this because my printer, the 2400, has the
usual
cyan, yellow, and magenta ink along with blacks. But in the bottom
green/blue part of the colored dots which is an INVERSION of the top
magenta
and yellow; the blue dots are not cyan. Cyan measured on the
computer
screen is R0G255B255 but the blue dot in my example is R0G0B255.
However,
I
do not know, unless I break apart a cyan ink cartridge and paint
with it,
whether my printer is mixing inks for that color or whether it is
the pure
ink out of the ink cartridge as is.
Does this make sense? That there are no actual CYAN dots in this
example?
I'll make one, though :)
I find that in the BW darkroom the yellow still holds true as being
dense,
as my negatives are red, and the closer to the magenta end of the
spectrum
I
go, the less light is held back. But I never use a pure yellow
negative
so
there is another factor going on than the actual density of the
ink, and
my
first guess would be the printer driver, second the wavelength of
light in
combination with the sensitivity of the particular process (bw
paper being
safe under yellow or red light).
Of course, the whole basis of PDN is the response of different
processes
to
different colors which is found in practice and not in theory (if I
used
theory to inform my practice I'd be a dead duck--thank heavens for
those
little step wedges and CDRPS and tonal palettes :). I never used
blue/purple negs, for instance, until solarplate.
WHEW, Loris, that was a way too long winded answer to your succinct
questions.
Please weigh in, Mark and Dan??!!!
Chris
__________________
Christina Z. Anderson
http://christinaZanderson.com/
__________________
----- Original Message -----
From: "Loris Medici" <mail@loris.medici.name>
To: <alt-photo-process-l@usask.ca>
Sent: Thursday, April 09, 2009 12:03 AM
Subject: green-yellow
Hi Christina,
I was looking at your visual about colors and UV opacity (here:
http://christinaanderson.visualserver.com/Text_page.cfm?pID=2448)
and
got
confused a little bit. Are those prints from the same process with
same
working paramaters and prodecures?
How Green (which is Yellow + Cyan) can hold back more UV than Yellow
alone, where Cyan is a poor UV blocker (slightly denser than
Magenta as
seen from your tests)? My experience with 3 different printers
taught me
Yellow is the strongest UV blocker among color inks... How come?
Regards,
Loris.
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