Re: Epson R2400 inks density
My measurements were made with a 361-T, which supposedly measures UV
in the 380 nm range
On Apr 29, 2009, at 4:10 PM, Don Bryant wrote:
Thanks for posting this. I don't use a 2400 but I still find the
the analysis interesting.
I assume the values labeled on the vertical axis A represent the UV
density of the ink plus base density of the Pictorico substrate.
How were the patches measured? That is what instrument was used? I
fire up my UV densitometer and do the same with my printers. Since
plots extending across a broad spectrum in the 300 to 900 nm range I
it's not likely you used a UV densitometer like the xRite 361T which
I know Mark Nelson has graphs of UV ink density published in his PDN
and Clay Harman has recently contributed some measurements with a
Epson printers, but I don't think those measure the same spectral
I also noted the 370 nm axis and I assume this is considered the mid-
for the range of UV frequencies that alt processes tend to be most
From: Alberto Novo [mailto:firstname.lastname@example.org]
Sent: Wednesday, April 29, 2009 4:52 PM
To: Alt-Photo Mailing List
Subject: Epson R2400 inks density
A week ago I gave to a friend of mine a print of YMCK and RGB
R2400 on Pictorico) for an analysis of their UV-VIS spectra, and now
the results. The graphs are posted in
What can be seen is that in the 320-400 nm region (UVA), the yellow
absorbance abruptly falls from about 3.6 at 400 nm to its minimum at
440 nm (A=1.5).
The other inks have a neatly different behaviour, with an absorbance
when going from 400 to 320 nm. The most dramatic change happens with
and cyan, which have an absorbance of about 0.75 @ 400 nm and
3.2 and 3 @ 420 nm.
The absorbance values of red, green and blue are not simply the sum
primary (CMY) colors at a given wavelength, but can be roughly
if the sum is multiplied by 2/3 (see for example the curves of C, B
the last two being C+M and C+Y, in the 600-750 nm region).
Moreover, the absorption of 50% saturated color patches (i.e. R=255,
B=128 for a 50% Y), that one likely thinks they should have 50%
of the full strength ones, are three or four times lower (not shown