Digital BW, The Print

Martin,
 
I've had a X-rite 810 for several years now. Your 811 is even a better
instrument. RGB does equal CMY. R= -C, G= -M, B= -Y. For B&W negs, the
811 should have a visual density (grey) mode. On the 810, this is
labeled T-VIS in the display.  You would use Status M color densities
for process control of C41 neg films, and Status A densities for E6. The
reflective mode should be Status A for reading prints. If your unit did
not come with a manual, you can buy one from X-rite. You also need
transmission and reflective calibration wedges from them as well.
 
Lloyd
 
 

-----Original Message-----
From: Martin Wesley [mailto:mwesley250@...] 
Sent: Saturday, October 19, 2002 2:00 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: [Digital BW] Reflective Densitometer Method


I am fooling around with a used X-Rite 811 transmission/refection
densitometry I picked up on eBay and I have a couple of questions for
any experts on sensitometry lurking out there.



In reading reflective density of inkjet prints there is the issue that
the paper is not completely opaque. You can see light though even the
heaviest papers we are using. So when measuring image density the print
being measured needs to be backed up with an opaque material. My
question is should this be white, as in stacking up several pieces of
paper under the print or should it be black? My inclination is to use
black so that no light that passes through the paper gets bounced back,
since this would logically seem to falsely increase the reflectance and
lower the density reading. The calibration plaques are enameled metal so
I assume the instrument expects to see a 100% opaque reflective target.



Dumb question: How do you convert RGB densities to CMY densities or do
they simply equal their color opposites?



The 811 has two transmission modes, one for E-6 and one for C-41. Which
would be the best for standard developed B&W film? Which mode would be
best for yellow/green stained pyro developed B&W film?


Martin Wesley

http://www.borderless-photos.de/guests.html




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