Digital BW, The Print

Hello!

I try to understand all the discussions regarding QTR ICCs and curves. I know 
what curves are, obviously. But is there some easy to understand what and how 
ICCS work? These are stored withing the image file? And PS as well as the 
Printer Driver reads these and adjusts the image prior to printing?

So, how do I see an ICC within a file? How, when and why would I create one?

I really want to learn this.

Thanks

Max



      

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Adventure Seeker <adventeseek@...> wrote:
>

> I try to understand all the discussions regarding 
> QTR ICCs and curves. 
>...is there some easy to understand what and how ICCS work?

Many others on this list are more qualified than I to discuss this.

For the full story, see http://www.color.org/iccprofile.xalter

These little ICC files basically tell the various parts of the computer system how to display or print the file -- what values the numbers of the file represent.

The monitor, for example, will always be "color managed."  If the file is "untagged" it'll display the file using the default working spaces (in Photoshop Edit>Color settings). 

The QTR ICCs are used in a several different ways to coordinate what is displayed on the monitor with how the print will look coming out of the printer.

I personally like to stay with as many industry standard settings as possible.  So, I have my PS RGB space set to Adobe RGB (1998) and my gray space set to Gray Gamma 2.2, which is a subset of Adobe RGB and sRGB.

My main use of the QTR ICCs is for printing with the Epson driver. The ICC has within it linearization data as well as a curve if I want it that controls the distribution of the inks.  This makes an easy workflow for printing gray gamma 2.2 files from Photoshop in a Windows environment without any further adjustments to the file.  What I see on the monitor is duplicated on the print with relatively good accuracy.

When I print with QTR as a stand-alone printer utility, I need to adjust my file so that QTR's literally linear and not-color-managed printing characteristics will produce a print that matches the monitor.  I use a PS curve to do this, but many use some standardized ICCs in the QTR download for this purpose.


The ICCs are stored at different places on different systems.  In Windows 7 they are at C:\Windows\System32\spool\drivers\color.  How the files are "tagged" is something someone else will have to handle.  To be portable, I assume the ICC is stored in the image file somewhere.

I have 2 PDFs on my web page that deal with ICCs. The first is http://www.paulroark.com/BW-Info/Making_B-W_ICCs-GrayCard.pdf which describes a way to use a flatbed scanner to obtain the needed linearization data.  Roy has since make a more complete Photoshop Script that can automate much of this.  It's part of the QTR download.

http://www.paulroark.com/BW-Info/Embedding_Photoshop_Curves_in_ICCs.pdf  describes how to put a PS curve within the ICC. 

Hope this helps.

Paul
www.PaulRoark.com

Wow! 
Paul, thanks for such a helpful post.
Andy

--- On Sat, 1/15/11, Paul <roark.paul@...> wrote:


      

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I hope this is not wandering off topic, but can someone clarify the
difference between qidf & quad files ? I downloaded some curves for 1800-3MK
with Ilford Gold Fibe Silk, and both types of file are included.
Chris.


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Chris Perfect <cperfect594@...> wrote:
>
> ... can someone clarify the difference between qidf & quad files? 

The *.qidf files go in the appropriate printer subfolder under \QuadToneRIP\Profiles\ .  The *.quad files go in \QuadToneRIP\Quadtone\.

The qidf files are the ones you work with in the Curve Creator.  When they are saved they generate the quad files that actually instruct the software what values to print.

Often I'll just post or send the qidf files because as soon as you pull one up in the Curve Creator and save it the quad file is generated.  Until you do that, however, the profile will not show up in the list you see in the QTR GUI.

Likewise, you'll notice that if you delete a qidf file in the Curve Creator the "profile" still shows up in the QTR GUI, because it's looking at the quad file in the other folder.

Paul
www.PaulRoark.com

Thank you Paul. Now I know why the profiles were not turning up in the list
!
Your input is really appreciated.
Chris.


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