Digital BW, The Print

Lincoln,

Channel Mixer simply defaults to 100% of the red channel upon opening,
but that doesn't mean it is the default B&W conversion formula for
Photoshop.  When you click 'grayscale' in Channel Mixer, it just jumps
to the first available channel, which is red, and leaves it at 100% so
you can start fiddling around with the sliders.  That gives you a
display of the Red channel only, with both Green and Blue channels set
to 0%.  It's just a blank canvas and a starting point.  

Looking at any grayscale conversion using Mode>Grayscale, you can see
that the result is not the Red channel only.  All the information I
can find suggests 30%R, 60%G, 10%B is about right for a standard mode
change.  If it isn't that, it is close.  

Sometimes a single channel provides the best conversion, or at least
comes close to the desired result.  It may be the red, green or blue
channel, but usually it is some combination of at least two channels.
 Since Hue and Saturation are no longer relevant in B&W, it's a matter
of selecting and blending those channels that give you the tonality
distribution and separation you want between tones.  And since we
don't see in B&W, we get to select the relationships we want.  Adobe
decided 3/6/1 was a good "general" formula for the "average" mode
conversion, but one size definitely does not fit all.  

Regards, Lou


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "outdoornm"
<outdoornm@...> wrote:
>
> John,
> 
> If that is true, why don't you see those values in the channel mixer
of a directly grayscaled 
> image?  If you directly grayscale an image Image>Mode>Grayscale, you
can no longer 
> access the image via the channel mixer. However, If you change the
profile of that same 
> image to RGB and go back in thru'  Image>Adjustments>Channel Mixer
you will see that 
> the default is 100% red.  ????? Why doesn't it read   R30% G60% B10%
since those are 
> supposed to be the values in each channel?
> 
> Lincoln
> 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "John Vitollo"
<jvlist@> wrote:
> >
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Eric
Neilsen" <e.neilsen2@> 
> > wrote: 
> > > I asked Julianne Kost of Adobe that very question a few years
ago and can't
> > > find her response. I'm pretty sure it was either 70G/20R/10B or
> > > 60G/30R/10B...but with my memory who knows. Guess you could
manually do
> > > those and see which more closely matches the RGB>Grayscale
conversion.
> > 
> > Photoshop's default grayscale conversion is: R-30%  G-60%  B-10%
> >
>