[argyllcms] Re: ArgyllCMS: shadow details and blue color issues. What I'm doing incorrectly?

  • From: "Xavi" <aruiz@xxxxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Fri, 19 Oct 2012 13:41:06 +0200

Hello Nikolay.
To print my photos I wish to use the intent that gives me similar results to
what I see on my calibrated screen or beeing more objetive, to the Lab
values that PS informs me that a color has.
I thought that the more simmilar results were offered by the relative
colorimetric intent. The other usually used intent, when speaking of
printing photographs, the perceptual intent, thought that was more visual
adaptative, than "real".
After receive your reply, I have printed, with absolute colorimetric intent
without BPC (is not posible to print with BPC option enabled),  the same 7
patches that I use to do my tests , and reading them with an spectro, the
deltaE values are between the results obtained with the relative
colorimetric and the obtained when printed with perceptual intent. But very
very near from the relative colorimetric. Exactly only a difference on
deltaE2000 of 0,20 and 0,32 of deltaE76.
When I try to show my profile results, specially of the blue color using
perceptual intent, Graeme Gill, commented me that he don't see the results
on my prints and that he don't know how the application that I use do the
soft proof.
Then I have decided to not to use soft proof to compare results.
Then, the only way that I think that I can compare results is printing
patches that I know their Lab value(photoshop gives me the Lab value of a
color when the cursor is over it), read these patches with an spectro and
calculate the difference between the Lab value of the patch and the Lab
value of the same patch printed on paper. I use the deltaE76 and the
deltaE2000. I think that a correct profile must have deltaE values near zero
when speaking of inside gamut colors. 
This method is correct? If yes, I must to print the patches using relative
colorimetric without BPC or absolute colorimetric intent?
If you have other ideas of how to verify if the workflow of creating a
printer profile, than use it and measure the results, please tell me it that
I will try it to check the results.
Any idea will be wellcome.
Thank you very much.

Best Regards,


De: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
En nombre de Nikolay Pokhilchenko
Enviado el: jueves, 18 de octubre de 2012 7:51
Para: argyllcms@xxxxxxxxxxxxx
Asunto: [argyllcms] Re: ArgyllCMS: shadow details and blue color issues.
What I'm doing incorrectly?

Thu, 18 Oct 2012 01:40:26 +0200 Xavi wrote:

I have added a new column, with the deltaE 2000, on the xls file that I
sent. Comparing deltaE00 with deltaeE76, I obtain lower values on deltaE00.
With an average value of 3,95 using relative colorimetric intent and 7,08
using the perceptual intent.

By deltaE You can actually check only the ablsolute colorimetric intent and
only the colors in the printer gamut. By cheking the relative colorimetric
intent You see white point adaptation dE between two media - standard and
Yours. By checking perceptual intetnt by dE, You check the "artistic
difference" which the profile introduces while gamut mapping transform. Both
checks didn't show "quality" of the profile. They only shows the difference
between media and difference of gamut mapping process. It's almost

I don't know if these are the values that I must obtain.

Thank you very much.

Best Regards,
Xavier Puente.

-----Mensaje original-----
De: argyllcms-bounce@xxxxxxxxxxxxx
rg>  [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
En nombre de Graeme Gill
Enviado el: lunes, 15 de octubre de 2012 8:48
Para: argyllcms@xxxxxxxxxxxxx
Asunto: [argyllcms] Re: ArgyllCMS: shadow details and blue color issues.
What I'm doing incorrectly?

Xavi wrote:
> On my case the softproof and the print are very very similar. On 
> prints, using perceptual intent, I see the blue color as a light 
> purple color, as I see on the screen when I softproof with Photoshop 
> CS6. Also checked on prints with 2 models of spectros using spot read.

I'm guessing that the image you are using is from the DQ-Tool
Monitor Reference File by Fujifilm Europe GmbH / Jens Rubb.
If so, it's an unlabelled (ie. no colorspace) RGB file.
The color of the "blue" fan bland is something like .09, .14, .55 RGB, so it
is not a pure RGB blue, but is tending a little towards purple in the
original, and all four of the soft proofs hint at this.

> Also the overall color is changed to a magenta cast, when I use 
> perceptual intent. Using the saturation intent the blue color is less 
> purple color and is more vivid but skin colors, for example, are more 
> reddish and excessive saturated.

I can't verify this - the profile through perceptual seems very self
consistent and neutral, ie:

icclu -fb -ip Argyllv140_396parxes48Gris3Blanc.icm
50.000000 0.000000 0.000000 [Lab] -> Lut -> 0.345472 0.388520 0.513978 [RGB]

icclu -ff -ir Argyllv140_396parxes48Gris3Blanc.icm
0.345472 0.388520 0.513978 [RGB] -> Lut -> 52.334969 -0.072152 -0.770024

< 1 delta E hue & saturation error seems reasonable through a perceptual B2A

It tends towards cyan as it nears the black point, due to Argyll's "extend
and bend" neutral mapping.

> I have created a collage with 3 cropped photos. Please, tell me if you 
> see the reddish/magenta cast on color skin. And also, if you agree 
> with me that the blue color of the sky, seems a blue/purple very light and
not saturated:
> http://i436.photobucket.com/albums/qq82/aaruizz/prcptualvsRC_zps09f2fe
> 42.jpg
> On the other hand I see very natural colors, on the right image, 
> softproofed using the same profile, but with the colorimetric intent.

You soft proof does look somewhat reddish - but then I'm not sure how your
softproof workflow is functioning. For instance, you are using BPC which
could be having an effect on the neutrals, given the very non-neutral black
point of your colorspace - ie. Argyll maintains neutrality down the neutral
axis until it nears the black point, at which stage it becomes cyan tint, to
match the black point. If the BPC then maps the cyan black to neutral with
the mapping being in a straight line to the white point, then the neutral
mid tones will get shoved in a megenta direction.

Note that typical Argyll workflows won't use BPC and are not created to
anticipate the effects of applying BPC, because you can do a more
sophisticated mapping using the collink gamut mapping machinery. My typical
softproof workflow is as follows:

# Create proofing transform from output to AdobeRGB collink -v -ila -G -qh
-cpp -dmt Argyllv140_396parxes48Gris3Blanc.icm AdobeRGB1998.icm

# Create proof image back in AdobeRGB space cctiff
Argyllv140_396parxes48Gris3Blanc_v.icm skin_sky_p.jpg skin_sky_pv.jpg

The above softproof (not using BPC) doesn't show such a tint.

> I am doing all the profiles with a Canon Pro9000MKII with third party 
> inks (Hobbicolors UW). I will do, from zero, new profiles for another 
> Canon MP540, that uses only four different color cartridges (CMYK) and 
> also I will start creating profiles, from zero, for the Pro9000MKII 
> but using cartridges refilled with other third party ink (OCP), that 
> uses a very neutral black color but that their gamut is more limited 
> vs Hobbicolors Ultra Wide Gamut inks.

I think a neutral black color will give better visual results, and leave
less room for workflow details to affect the outputt.

Graeme Gill.

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