Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@y..., mwesley250@e... wrote:

> You are setting a custom curve for grayscale I assume by printing out 
> a step wedge and visually calibrating the screen to match.

---Correct


 But if you 
> are working in a RGB space even with a channel layer set to mono 
> would the custom grayscale curve apply?

----No. Not while in RGB. It will apply at the moment of transition from RGB to 
gray. You can set up ways to preview, but that's not the issue here.

> Is there enough difference between the channels to provide useable 
> information at the print level?

----- That depends on the specifics of the scanner.

> 
> As a thought, what if you modified the gamma of each channel slightly 
> to increase the difference between them?

---- Possibly. Or a for a given tweak you may only use one or two channels.

>  In the mode change 
> Photoshop is also performing a conversion from one profile to another.

---- Correct!
 
> I am beginning to wonder if the 8-bit space is as fragile as we have 
> been thinking. After doing some identical manipulations of raw scans 
> at 16 and 8 bit to the point of heavy combing of the 8-bit histogram 
> I am not seeing any difference in the print quality. Not to say that 
> there would not be a difference at some point but a bad 8-bit 
> histogram does not automatically mean a bad print. It may mean you 
> are getting close to the edge of posterizing but that edge may be 
> image dependent.

----- That's exactly my understanding too. If you have a subtle gradation over a 
long distance - say a clear sky that goes from 11 to 18% percent - you are 
more likely to notice a difference. Even then, nothing a little noise couldn't fix. 
Even 2% noise will fill in a gap-toothed histo.

> The theory is sound but I don't know how much you are really getting 
> in print quality at the end because of the very close similarity 
> between the three channels to start with. You are also paying a 
> performance price in working with the bigger files.
> 
> My feeling is that for a normal negative requiring moderate 
> adjustment there might be no gain but for manipulating a difficult or 
> marginal negative perhaps. Really need to try it from scan to print 
> both ways and see if there is a detectable benefit.

---- It isn't so much about the 3 channels or the histogram as much as it is 
about the distortion introduced in the workflow when working in grayscale and 
have already calibrated to a printed reference by adjusting the gray curve (in 
the color prefs).
The minute you change that gray curve for an alternate use, your whole 
dodge-and-burn goes out the window because it was done for that specific ink 
and paper.
The other benefits are secondary; though, considering Paul's RGB workflow, 
I'd say the whole grayscale thing should stay in RGB.

Antonis