Digital BW, The Print

Steve,

I see from your  post that we are working with different QTR curves, 
hence my profile assign/convert approach is different.

I've made my QTR curves by eye, without measurement, to match gamma 2.2 
working space because I  don't have a densitometer to measure the 
output. So I have not used the QTR linearize function. Believe it  or 
not, I've been quite successful at creating these curves (there was a 
bit of learning by  trial and error  involved but I've got  it down 
pretty good now).

So am I correct now in assuming that the Linearize function in QTR 
linearizes to LAB values? If so the LAB grey space makes perfect sense 
to match the Linearized output. I assume that the Linearized QTR/LAB 
output is not an exact density match to the monitor, but the perceptual 
change of densities in a printed step wedge matches the perceptual 
change of the step wedge in LAB/grey working space.  A "perceptual" 
working space conversion if you will.

So far, so good. My question: How does this approach deal with the 
reduced density range of a print vs. the monitor w/o softproofing by 
measured output?

IOW, I suspect that one still needs the softproof in addition to the 
LAB/grey space and Linearized output curve for true WYSIWYG printing. 
Still the LABgrey space combined with the LAB based Linearization seems 
to be a great starting point to standardizing the printer behavior. So 
now I'll have to find a densitometer?

Cheers,
-bruce


On Friday, Dec 10, 2004, at 08:53 US/Pacific, 
DigitalBlackandWhiteThePrint@yahoogroups.com wrote:

> Message: 8
>    Date: Fri, 10 Dec 2004 12:59:11 +0000
>    From: Steve Kale <stevekale@...>
> Subject: Re: Re: LAB Step Wedge -- a grayscape Lab space
>
>
>
>> I'd first like to say that the best thing to do is try things out and 
>> see.
>>
>> But here is my reasoning.   The QTR curves/profiles aren't based on 
>> the
>> photoshop gray space at all.  When you print and select "Same As 
>> Source"
>> you are just passing the data through without modification.  QTR gets
>> the raw data.  When you did all the linearization it was based on raw
>> pixel data -- it was not at all dependent on the gray space.
>
> Yes this is correct.  We measure the density printed for a the image 
> file's
> "raw data" and then feed this back into the equation via LINEARIZE=
>
>> So the
>> existing QTR profiles should work just fine as long as the pixel 
>> values
>> don't change, hence Assign-Profile.
>
> This would work if the print space was LAB but it isn't.
>
> Cheers
>
> Steve