Digital BW, The Print

Hi,
my current images are stitched to try and get into the 30-50 megapixel area.

The thing is: I like to do as much as I can in ACR, because I've found that this really helps the end result. 

But PhotoMerge outputs an RGB file and I've not found a way around that. Have I missed something?

It seems silly to convert to Gray Gamma 2.2 in ACR, only to have PhotoMerge change it to ProPhoto. An unnecessary double profile conversion to ProPhoto RGB and back to Gray Gamma 2.2.

But if this is unavoidable, perhaps outputting from ACR as sRGB or aRGB might mean there is less data pushed around in PhotoMerge's profile conversion, due to the smaller colour spaces?

I really don't know how much profile conversions degrade an image and how much different any degradation is when converting to or from a wide gamut space, as opposed to, say, aRGB or the even smaller sRGB.

Any thoughts?

thanks,
Richard

--
richard smallfield photography
http://smallfield.vze.com 

   "If history repeats itself, and the unexpected always happens, 
   how incapable must Man be of learning from experience."
   --George Bernard Shaw

Richard,

As a disclaimer: I'm not a color space expert, so this is just my 2 
cents.

My understanding about errors introduced by converting from one 
colour space to another ist that they occur (mostly?) on the edges of 
the colour space, i.e. the most saturated colors. Mapping those 
extereme gamut colors between color spaces involves approximations 
and heuristics. Doing that repeatedly between many spaces will leave 
you in the end with smallest gamut that fits in all spaces. So a 
repeated conversion will compress, perhaps clip, your gamut.

But frankly, why are you bothered by that as B&W photographer?? I've 
never tested this, but I have great difficulty to understand that 
these errors would be of any practical relevance whatsoever if later 
in the process you apply the biggest color space compression 
possible: B&W conversion.

Joost

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Richard 
Smallfield <r.smallfield@...> wrote:
>
> Hi,
> my current images are stitched to try and get into the 30-50 
megapixel area.
> 
> The thing is: I like to do as much as I can in ACR, because I've 
found that this really helps the end result. 
> 
> But PhotoMerge outputs an RGB file and I've not found a way around 
that. Have I missed something?
> 
> It seems silly to convert to Gray Gamma 2.2 in ACR, only to have 
PhotoMerge change it to ProPhoto. An unnecessary double profile 
conversion to ProPhoto RGB and back to Gray Gamma 2.2.
> 
> But if this is unavoidable, perhaps outputting from ACR as sRGB or 
aRGB might mean there is less data pushed around in PhotoMerge's 
profile conversion, due to the smaller colour spaces?
> 
> I really don't know how much profile conversions degrade an image 
and how much different any degradation is when converting to or from 
a wide gamut space, as opposed to, say, aRGB or the even smaller sRGB.

> 
> Any thoughts?
> 
> thanks,
> Richard
> 
> --
> richard smallfield photography
> http://smallfield.vze.com 
> 
>    "If history repeats itself, and the unexpected always happens, 
>    how incapable must Man be of learning from experience."
>    --George Bernard Shaw
>