Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Antonis 
Ricos" <antonisphoto@y...> wrote:
> Since the densitometer I'm currently using 
> > does not conform to any specific ANSI standards I don't think 
a 
> > comparison of these values to ones from another 
densitometer would be 
> > very meaningful.
> 
> Carl and Phil,
> 
> using a densitometer with standard density readings is 
essential if you are 
> using IJC. In this case, the discrepancy in the results or 
readings between two 
> different users would be made greater by non-standard 
instruments.
> 
> What you get with a non-calibrated instrument is still a smooth 
curve, i.e. when 
> you plot your grayscale output it will make a smooth curve and 
that should 
> help produce nice separation between steps etc.  But you'd be 
missing out (a) 
> on achieving maximum density and (b) on proper overall 
gradation in parts of 
> the scale. That would depend on the actual shape that you 
would get in  that - 
> otherwise smooth - curve of the plotted densities. 
> 
> IJC is based internally on an ideal set of densities which it 
generates for a 
> given dmax and paper white set of values. If you can't track 
those properly 
> because of an out of whack instrument, you are simply 
missing some - but not 
> all -  benefits of the system.

Yes, I agree with all that.  But since I only have the OPM part of 
the "system" (thus far), I merely wanted to use densitometry for 
determining (even semiquantitatively) how  large are the 
differences between _my_ two grayscales: one from a profile 
used in OPM 1.02 versus another from same profile used 
with a different OPM version. That tries to answer a basic 
question that was raised about possible version-to-version 
effects. Even with an uncalibrated densitometer (the_same_ 
uncalibrated unit), it should be possible to determine whether or 
not there are significant differences (especially changes in the 
curve shape.)  Agree?

Now that I've just made those measurements, I am able to verify 
what 
my eyes had been telling me: the grayscale density curve  from 
OPM 
1.02b5 has a rather pronounced inflection near midscale--quite 
different from the smooth, monotonically increasing density 
curve from OPM 1.02. Also, 1.02b5 gives  higher densities overall  
(especially near midscale); even a bit higher at 100% black, too.  
That's all using Carl's "cool" EAM_MK linearized profile.

Any comparison of my densitometric curve with data from Carl's 
also-uncalibrated densitomer would only be useful to verify that 
I'm able to obtain a similar curve shape when using the same 
profile and OPM version as he used. The only reason to even 
raise that question is that my 2200 had that streaking "problem" 
while his did not.

Phil