Digital BW, The Print

Thanks Mike, Did that answer your question Barry? Oh and the switch 
to Reflectance from Transmittance is a good piont- I just copied the 
definition for the math. 

Jeff.

> Barry,
> 
> If dmax is 1.8 and dmin is 0.05 then the Density Range is 1.75.
> To find what percentage of the Density Range .6 is 
divide .6/1.75=0.34 
> or 34%
> 
> Mike
> 
> On Tuesday, April 23, 2002, at 08:31 PM, flyfishingusa2002 wrote:
> 
> > Jeff,
> > Thanks for the math! Now here's the question, If Dmax = 1.8 and 
Dmin
> > = 0.05 What percentage of the dynamic range is, say, .6? Can you
> > show us how to do it?
> >
> > Barry
> >
> > --- In DigitalBlackandWhiteThePrint@y..., "iwasnvrhere"
> > <iwasnvrhere@y...> wrote:
> >>     This might help.
> >>  optical density (OD): For a given wavelength, an expression of
> > the
> >> transmittance of an optical element. Note 1: Optical density is
> >> expressed by log10(1/T ) where T is transmittance. (188) Note 2:
> > The
> >> higher the optical density, the lower the transmittance. Note 3:
> >> Optical density times 10 is equal to transmission loss expressed
> > in
> >> decibels, e.g. , an optical density of 0.3 corresponds to a
> >> transmission loss of 3 dB. Def of optical density.
> >>
> >> Jeff
> >>
> >>
> >>
> >>
> >>> John,
> >>> You are at the same point as I am. Well, actually I'm a little
> >>> ahead. The density readings are log to the base 10 so dividing
> > the
> >>> Dmax by 2 will not give you the expected 50% reading. I am
> >> currently
> >>> trying to figure out the math.
> >>> I will let you know when I get there,
> >>>
> >>> Barry
> >>>
> >>> --- In DigitalBlackandWhiteThePrint@y..., John Chervinsky
> >>> <chervinsky@d...> wrote:
> >>>> Hi,
> >>>>
> >>>> I am attempting to calibrate my printer output using a
> > calibrated
> >>> X-Rite 810 densitometer.  I am using MIS FS inks through an
> > Epson
> >>> 1160 onto PhotoRag 308 paper; I am on a Mac computer.  I realize
> >>> that this question has come up in the past, but practical
> > elements
> >>> of technique were omitted.  Below you will find the reflective
> >>> densitometer (visual) output vs a 21 step stepwedge.  I did
> >>> measurements using both the Randall and Piezography workflows.
> > If
> >>> you look at the numbers carefully, you will conclude as to how
> >>> shockingly non-linear they are.  I would have expected, for
> > example
> >>> that the 50 % reading would have been close to 1.7/2 = .85.  The
> >>> Measured value of around 0.6 is WAY off!
> >>>>
> >>>> Has anyone else had this experience? I would not think that my
> >>> paper choice would have that much effect.  Are there subtle
> >>> differences in using a reflective densitometer as opposed to a
> >>> spectrophotometer to do the measurements? It would seem that for
> >>> grayscale work that a densitometer should be fine.  Please
> > advise.
> >>>>
> >>>> Thanks!
> >>>>
> >>>> -John Chervinsky
> >>>>
> >>>>
> >>>>
> >>>> STEPWEDGE  CONE      RANDALL
> >>>> 100.0     	1.71     	1.77
> >>>> 95.00     	1.54     	1.66
> >>>> 90.00	     1.40     	1.57
> >>>> 85.00	     1.26     	1.45
> >>>> 80.00	     1.15     	1.33
> >>>> 75.00	     1.05	     1.20
> >>>> 70.00     	0.96     	1.07
> >>>> 65.00	     0.86     	0.95
> >>>> 60.00     	0.78	     0.83
> >>>> 55.00     	0.69      0.76
> >>>> 50.00	     0.61     	0.66
> >>>> 45.00	     0.54     	0.58
> >>>> 40.00	     0.48	     0.48
> >>>> 35.00	     0.42     	0.39
> >>>> 30.00     	0.36	     0.32
> >>>> 25.00     	0.29      0.27
> >>>> 20.00	     0.24     	0.21
> >>>> 15.00	     0.19	     0.17
> >>>> 10.00      0.14      0.13
> >>>> 5.00	      0.09	     0.09
> >>>> 0.00	      0.05	     0.05
> >
> >
> >
> > Please visit the Group Homepage to check the Files, Bookmarks, 
Polls 
> > and other resources as they are often being updated. The page is 
at:
> >
> > http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
> >
> > Please follow these basic guidelines:
> > - Include your full name with your message.
> > - Include the address of your website, if you have one.
> > - As threads develop, trim off excess portions of earlier 
messages to 
> > keep them short.
> > - As the topic of a thread changes remember to change the subject 
> > header.
> > - Good manners are required at all time. No personal attacks or 
> > "flames."
> > - Complete your Yahoo profile.
> > - Before posting a question, search the message archives and the 
> > various resources on the homepage.
> >
> >
> >
> >
> > Your use of Yahoo! Groups is subject to 
> > http://docs.yahoo.com/info/terms/
> >
> >