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Masking, Part 1



Dave Schrader wrote about masking several weeks ago and I sent the
response below.  Dave has been trying to post an excellent response
without any success so I will try to post his detailed and informative
answer.  Thanks Dave!

It failed for me too.  I do not know if there is a size limit and that
is wy it does not show up.  This time, I am splitting it in four parts
and hopefully it will work.
Bertho


===============================================
<<<< My previous posting: >>>>>
This bit of information is intriguing.  I am trying to design color
filters using printers and a clear transparency film.  It sort of looks
like an overhead transparency.  My goal is to be able to select
different colors and have as low transmission loss as possible for that
selected color (wave length) and suppress the other wave lengths as much
as possible.  I have the proper spectrometric equipment to measure the
printed films.

I understand the need for black in the printers and why it is used but
part of your description triggered my interest.

Now finally the questions:
What is masking and how is it used?
Any suggested reading material for really understanding the different
ink processes.
TIA
Bertho Boman

========================================
Dear Bertho,

Sorry for the late reply.  I attempted to post this several times to the
Inkjet list, but for whatever reason it never appeared.  I'm guessing
that I was censored by the list owner; maybe the content is too far off
track?  I e-mailed Leben directly but he never replied so I gave up.
Kind of makes me mad, but it's out of my control so no sense in losing
any sleep over it.

Anyway, here's the response that I wrote to the list in regards to your
questions:

(From 5/6/02):

Wow, your questions cover a lot of ground, but I'll give it a shot. I'll
try and describe a basic color masking scheme that I used to employ back
in my dye transfer days. So here goes:

The term masking can cover a lot of different areas.  In dye transfer,
there's overall contrast reduction masking, highlight masking, specular
highlight masking, and color-correction masking.  There's also various
masking schemes that apply specifically to offset (which fortunately is
built into separations automatically so we don't have to mush our brains
thinking about it).  All processes that use the subtractive primaries
(cyan, magenta, and yellow) to reproduce color require masking of some
form.  In our Epson inkjet printers, "masking" is performed
electronically via the print driver and we never have to give it a
second thought.  And probably the most important type of masking is for
color correction.

Here's the problem: the color dyes and inks that make up our
photographic world are far from perfect.  Whether it be the dyes in
Ektacolor prints, Ilfochrome prints, offset lithography inks, Epson
inks, you name it; cyan, magenta, and yellow all have spectral
deficiencies; you'll see this described in books as dye deficiencies,
but it applies equally to inks if not more so. The problem isn't so much
in originals (i.e. slides) but rears its ugly head when we try to
reproduce them. So here's what's going on:
<<<<< to be continued >>>>>


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