[argyllcms] Re: collInk for softproofing

  • From: "Xavi" <aruiz@xxxxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Fri, 19 Oct 2012 14:56:40 +0200

Hello Diego.
 
"In any way normally I use the Icm file I create with argyll with colprof to
make my softproof in photoshop, Is this procedure correct? Or not at all."
 
I have always used this option on Photoshop to soft prooft all the ICM
obtained with different software with apparently "visual" good results. I
imagine that the obtained ICM with ArgyllCMS must not be different.
 
But now I doubt of all. Then I am checking deeper all the steps and recheck
the results. And I'm trying to measure all, instead of use my subjectivity.
 
But my results after measuring each step, aren't good. If I softproof on PS
with the "normal" method I can view the Lab values of the softproofed
patches. Then what I do is to CONVERT the image to the printer profile. Here
I can see the Lab values of the "softproof" that aren't the same Lab values
on prints, using the same intent than the conversion process.
 
If I calculate the softproof value for a patch using the next method:
 
.\icclu -fb -ip
MP_B01_A4_HPEverydayBrilloIIQ1Dif_NoVPre_396p64g3bArgyllv140_121011Opcio_qm_
ACPU.icm

28.87   14.81   -50.15

28.870000 14.810000 -50.150000 [Lab] -> Lut -> 0.358232 0.399245 0.879326
[RGB]

 

.\icclu -ff -ir
MP_B01_A4_HPEverydayBrilloIIQ1Dif_NoVPre_396p64g3bArgyllv140_121011Opcio_qm_
ACPU.icm

0.358232 0.399245 0.879326

0.358232 0.399245 0.879326 [RGB] -> Lut -> 39.085966 11.557139 -49.964686
[Lab]

 

The Lab value is not the same that the printed patch and also different to
the values obtained on the PS conversion.

 

Could be the "softproof" term an approximation but not a exact method?

 

If you want to check if your softproof method works, I think that a valid
method must to be print the simulation of color checker card (I print it to
a width of 9,5cm to accomodate 8 cards in an A4 sheet) that I attach you
(you can download all from
http://www.babelcolor.com/main_level/ColorChecker.htm#ColorChecker_images),
and read the print patches and compare with the theorical values that you
obtain with the softproof.

 
If you check it, please comment your results then I can compare with my
results too.
 
Best Regards,
Xavi.
 


  _____  

De: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
En nombre de Diego Carra
Enviado el: jueves, 18 de octubre de 2012 8:29
Para: Argyll list
Asunto: [argyllcms] collInk for softproofing


Hello recently our belowed Graeme Gill posted these command to user Xavi
telling could be good for softproofing
 
# Create proofing transform from output to AdobeRGB collink -v -ila -G -qh
-cpp -dmt Argyllv140_396parxes48Gris3Blanc.icm AdobeRGB1998.icm
Argyllv140_396parxes48Gris3Blanc_v.icm

# Create proof image back in AdobeRGB space cctiff
Argyllv140_396parxes48Gris3Blanc_v.icm skin_sky_p.jpg skin_sky_pv.jpg
 
So I tried these command but probably unfotunately i miunderstand the real
power of these command
 
Now I tell you what I did.
 
I though to use all the two command with an image of mine and using .icm
file created for a backlit panel to arrive to a jpg file show me the
softproof.
 
But Unfortunately the jpg I arrive is really jellowish and tint uncolored.
(unfortunately I can't show you becouse is publish protected copyrith)
 
So I ask you the ICM profile I arrive with collink could be used in
photoshoph to soft proof? 
In any way normally I use the Icm file I create with argyll with colprof to
make my softproof in photoshop, Is this procedure correct? Or not at all.
 
tahnking you for any help I send you my best regards.
Faithfully
Diego Carra 
 
 

Attachment: ColorChecker_AdobeRGB_from_Lab_D50.tif
Description: TIFF image

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