Digital BW, The Print

Johnny,

When you are looking at the 127 or 148 values you are looking at the
RGB conversion of the grayscale value.  The reason you are getting
different values when GG is 1.8 rather than 2.2 is that they convert
differently to the working RGB space.   You probably have Adobe RGB for the
RGB space which is a gamma 2.2 space, so a 50% K value in GG 1.8
(which internally is 127) will convert to 148 in the Adobe RGB space
and that's what you will see in the Info palette.

My recommendation would be to use the same gamma in both GS and
RGB.   Gamma 1.8 would correspond to Apple RGB, and Gamma 2.2
would correspond to Adobe RGB.   

There's a hidden feature in Photoshop to see the gamma of an RGB space:
  select the RGB space you want in Color Settings.
  then select the same pull down again but go to Custom RGB ...
  you will see the details of the previously selected RGB space.

Roy



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Johnny Eades" 
<jeades1@s...> wrote:
> Hello Paul,
> 
> GG 1.8 is my working gray profile defined in color settings in 
> Photoshop. The monitor is set at GG 1.8 and Photoshop is set at GG 
> 1.8. The 21 step grayscale is showing 148 at 50% at GG 1.8, and it 
> shows 127 at GG 2.2 (if I assign it GG 2.2). I do all of my work at 
> GG 1.8 now. I just am curious as to the reason for the majority of 
> the Grayscales I've seen using 127 as the 50% reading.I someone had a 
> monitor set at GG 1.8 and didn't know it, they would have a hard time 
> getting the numbers to match the grayscale; wouldn't they?
> 
> 
> Your friend in Photography,
> 
> Johnny
> 
> 
> 
> 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul D. 
> DeRocco" <pderocco@i...> wrote:
> > > From: Johnny Eades [mailto:jeades1@s...]
> > > 
> > > There has been something I have noticed when I changed from Gray 
> > > Gamma 2.2 to Gray Gamma 1.8. When I have the 21 step grayscale 
> which 
> > > has the density marked in percentages,and I pass the eyedropper 
> tool 
> > > over the 50% square and am using GG 1.8; the number of the 
> percentage 
> > > is 58% and the number relative to 0 to 255 is 148. If I reset the 
> > > Gray Gamma to 2.2 the numbers match the grayscale markings.I have 
> > > come to realize the grayscale was intended to be viewed at GG 
> 2.2. 
> > > Does anyone have a grayscale that is calibrated with the numbers 
> to 
> > > be viewed at GG 1.8. Even the grayscale from PiezographyBW is 
> marked 
> > > like the GG 2.2 scale and Jon Cones recommends the monitor and 
> the 
> > > workspace of Photoshop both be GG 1.8. Has anyone else dealt with 
> > > this question and resolved it to their satisfaction yet? If so 
> please 
> > > share with this group. I wouldn't think I was the only one 
> noticing 
> > > this anomaly.
> > 
> > Just assign the 1.8 profile, instead of converting to it.
> > 
> > -- 
> > 
> > Ciao,               Paul D. DeRocco
> > Paul                mailto:pderocco@i...