Thanks Steve for replying.
I also did ask the question on the Inkjet_PCB_Construction but there were no
replies. Most work there appears to be aimed at direct printing on PCBs vs.
creating an artwork and using photo resist.
Your Amiga comment brings back memories of the original Amiga that I had.
If color management is disabled in Windows and the printer driver, how can I
find an RGB value for each of the CMY colors?
I have spent the last day and a half measuring resolution and ink densities
for different materials, settings on two different printers and some
interesting and surprising info has been learned:
In some cases, even if "gray scale" is selected the printer regardless uses
color.
For some paper types the gray scale option is not available.
For some combinations the UV density is much worse than the visible spectrum
density.
Bertho
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From: AlienRelics Sent: Sunday, October 09, 2011 09:33
Shouldn't we be having this discussion on Inkjet_PCB_Construction?
Yes, all printers use CMYK or an expanded version. The most common are a
light version of Cyan and Magenta, sometimes a "photo" black that may be a
grey. They are usually indicated by lower-case letters such as CcMyYKk. Some
expensive printers have additional colors, green and orange as they can be
very hard colors to hit correctly. Some printers have additional shades of
grey. These are all to avoid the appearance of visible ink dots in light and
evenly colored areas, widen the color gamut (range of shades printable), and
to avoid color and texture shifts.
RGB only works for additive things like monitors. CMYK is subtractive. Add
100% Red, Green, and Blue on a screen and you get white, add the maximum
Cyan, Magenta, Yellow, and Black and you get Black. Try mixing paints in
Red, Green, and Blue, and you'll find there are many shades you can never
get. Green and Blue only add to yellow if you are mixing light. Mix inks or
paints, Green and Blue become a muddy dark green-blue color.
The confusion likely stems from the fact that the printer driver for desktop
printers only accepts files in RGB color space, then converts them to the
printer ink color space. CMYK, CcMmYKk, etc.
Separations won't help you - the separation, if printed on your home
printer, will still be just an image file that will be printed as if it were
an RGB color space file in black, which gets converted by the printer drive
to the printer CMYK color space.
Using CMYK within Photoshop can help a little, but ultimately all files
printed first get converted to RGB before getting sent to the printer
driver.
What you really need is a RIP, but those tend to be expensive. There is
Turboprint Studio, which I've not used since I had it on my Amiga 3000, but
there is a version for Linux. The Amiga version of TurboPrint Studio 2 let
you control every ink, so you could set it to print only in one particular
ink.
http://www.turboprint.info/I see the programmer has a version for Windows and Mac called PrintFab.
Appears to still be in beta testing.
http://www.printfab.com/en/You could also find a color in RGB that prints mostly magenta and/or cyan.
BTW, the C82 is not a "photo" printer in the meaning of having the lighter
color inks such as photo cyan and photo magenta. It is a four color CMYK
printer. Still, the printer driver only accepts RGB image files and does the
conversion to the printer's CMYK inkset.
Steve Greenfield AE7HD
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