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Re: [OM] How do I use chemical process print paper profiles in PhotoShop

Subject: Re: [OM] How do I use chemical process print paper profiles in PhotoShop?
From: Chris Crawford <chris@xxxxxxxxxxxxxxxxxxxxxx>
Date: Tue, 01 Dec 2009 15:21:28 -0500
Chuck, glad I could help. I got expert in this stuff, color management,
years ago when I first began using my film scanner and an epson printer. It
was a nightmare because back then little reliable info was out there and it
was all very obscure and hard to understand. Things are easier now, there
are some good books out there that explain this stuff in plain english, but
I still think color management is the hardest thing about digital mage
processing. There are so many variables. Is he monitor calibrated right? Is
the monitor even capable of proper display? Most LCDs are almost worthless
in my experience if you want exact or near-exact matching from screen to
print. Most are too bright and to make matters worse, most Calibration
systems have you use way too bright of a white point when they calibrate
your screen (should be 80cd/sq inch). My Eye-One Display said to calibrate
LCDs to 120 cd/sq in, and that is WAYYYYY to bright. I now have a
self-calibrating NEC screen that automatically sets itself to 80 for
brightness and D65 for color temp. Works perfect, but expensive. The old CRT
screens were better, even cheap ones worked well. With LCDs the cheap ones
often are not capable of the accuracy of color needed and are too bright
even at the dimmest settings :(

Yep, you had it right. The choice between Perceptual and Relative
Colrimetric is called the RENDERING INTENT> What it does is it controls the
manner in which colors are converted from your editing colorspace (sRGB) and
your output colorspace (the printer profile). Like I said some profiles seem
to be optimized for Perceptual, some for Relative Colorimetric. Perceptual
is most common. You can't trust the instructions that come with the profile
(if it came with any). I have gotten profiles from labs before with
instructions to use one of the rendering intents, only to find that the
opposite choice gave the best results! That's why I say to try them both.

Oh, I forgot....when you do the conversion, there is a checkbox that says
"Use black point compensation". Make sure its checked.



-- 
Chris Crawford
Fine Art Photography
Fort Wayne, Indiana
260-424-0897

http://www.chriscrawfordphoto.com  My portfolio

http://blog.chriscrawfordphoto.com  My latest work!


On 12/1/09 2:56 PM, "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx> wrote:

> Thanks.  I guess I had it sort of half figured out when I said:
> "Or do I need to generate an output file that is filtered through the
> paper profile in a manner similar to generating the output data that
> goes to my inkjet printer?"  I just didn't know how to do it.  Now I do.
>   Thanks again.  And I'll take your advice on having the same test print
> done multiple ways.
> 
> Chuck Norcutt
> 
> Chris Crawford wrote:
>> Chick,
>> 
>> Soft proofing doesn't really work well with RGB profiles, is it more
>> effective with CMYK press profiles because those presses lose a lot more
>> color range compared to what the monitor shows. When preparing files for an
>> RGB printer like a Fuji Frontier or other digital minilab, or for an inkjet
>> printer (injets are designed for RGB input despite using cmyk inks).
>> 
>> Here's what you do: Make the image look the way you want in sRGB, then
>> convert to the printer profile you have using the 'convert to profile'
>> command. You'l probably want to do this using Perceptual rendering. Many RGB
>> output profiles give bad results using Relative Colorimetric. An easy test
>> is to take a file and convert it both ways and send both files to the lab
>> and see which looks closer to your screen. But I am betting on Perceptual.
>> 
>> Save the converted file under a new name so you don't lose the original sRGB
>> version. When you save, DO NOT embed the profile....Fuji Frontiers don't
>> like to see an embedded profile. Then, send the converted file to the
>> printer. Your print should be pretty close if your screen is calibrated
>> right.
>> 
>> 


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