U of S | Mailing List Archive | alt-photo-process-l | Re: green-yellow

Re: green-yellow

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

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.

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.