A basic guide (see post #1) to setting up ARGYLL CMS profiling on your computer

[Emulator]

I have been experimenting with Argyll, just for the fun of it and tried a 3 x A4 sheet of 2250 patches. I pushed up the B&W content by three times to 384 patches, 24 being black and 24 being white out of the 384. Difficult to say whether it is really any better than the 750 patch version. Here is a B&W test chart printed and scanned. It seems the black end is cramped, but I suspect it is an example of a poorer Dmax. In the centre is the original file image.

I am not sure whether Argyll has black point compensation switched on, or if you have a choice. The posted image difference looks worse than the real thing, possibly through the scanning process.

The third image is the Gamutvision B&W density response, without black point compensation, for the 2250 profile, which claims Dmax as 2.34, the dog leg is presumably related to the cramping.

 

[pharmacist]

So actually 750 patch is more than enough to create good profiles. Like I have said: most printers are linear enough to get more than satisfactory profiles with a relative limited amount of patches. Any extra patches would be overkill. However: CMYK profiles will need at least 10^3 + 128 grey patches to generate good profiles.

 

[pharmacist]

Today I produced a new profile for SihlX paper (United Office from Lidl) for the Inkowl fade resistant refill ink (Epson 1500W) using the 750 patch ArgyllCMS method and compared it to my Colormunki produced profile using 2 optimisations. The ArgyllCMS profile renders much more natural pictures (better skin tones, much more neutral black&white images, better shadow details) compared to the Colormunki produced profile. The Colormunki profile yields a yellowish cast on the picture. On printers with K3 inks, there is no much difference in the B&W prints between Colormunki and ArgyllCMS, but it is clearly visible on printers without dedicated grey inks, like my Epson 1500W.

Because the ArgyllCMS method only needs a one-step-reading, profiles can be produced in one run, without the 10 minutes two-step method of the Colormunki. Some inks need a considerable time to cure and to obtain the final color. A 24 hour drying time is sometimes necessary.

For those interested I have uploaded this ArgyllCMS created profile for United Office Sihl 280 gsm glossy paper on the Epson 1500W printer and using Inkowl Fade Resistant Claria compatible dye ink.

 

[RogerB]

For those interested I have uploaded this ArgyllCMS created profile for United Office Sihl 280 gsm glossy paper on the Epson 1500W printer and using Inkowl Fade Resistant Claria compatible dye ink.

Hi Pharmacist,

Thank you for uploading that - as you may have guessed I could not help having a look at it!

The colour accuracy for colours in the Macbeth Colorchecker does look extremely good, and since these colours represent a very large proportion of the colours present in "real" images it agrees with your comment that this profile renders more natural pictures. However, according to the profile analysis, the B&W response is a bit strange. The neutrality is extremely good over most of the density range but in the darker tones there appears to be a step change in contrast when using the Colorimetric renderings. This step is not apparent in the Perceptual rendering. The effect of the step is very obvious in a soft-proof of a circular gradient (see third image).

I would be very interested to know if this behaviour is seen in an actual print of a circular gradient like the one above, or is the analysis misleading?

 

[pharmacist]

Hi RogerB,

Have a look at this scan (especially the black&white regions) of the following scan:

Above is done with the Colormunki profile, the one below is with the ArgyllCMS. Both prints using the perceptual intent when printing.

I will have a softproofing using this image and see how the grey gradation steps behaves to the colorimetric intent settings.

 

[pharmacist]

I just discovered indeed some (reading ?) errors in the dark area's according to the softproofing of PS. This is the tricky part of the extreme small patches used to create the profile. A slight reading error can cause strange errors in this particular regions.

 

[Emulator]

@pharmacist, I am trying to comprehend some of the options to the colprof command and notice that -i D50 -o 1931_2 interrelates with the presence or otherwise of optical brighteners and whether the measuring instrument has UV filtering.
The Sihl paper has OBA and the ColorMunki has UV filtering or a white LED without UV content.

So does this Argyll guidance statement:-

Similarly, the effects of viewing the media in an environment with a UV filter fitted over the D50 illuminant can be simulated by using FWA compensation with the D50M2 illuminant, and the 1931_2 observer, thereby simulating the results one would get if the media had been measured with a "UV cut" type instrument, although such profiles are not technically ICC compatible.

mean that we should be using the D50M2 option rather than the D50?

 

[Emulator]

I have produced a different version of the colprof batch file, which I have named createprofile.bat.

This version uses the same name for both the internal ICC Description file name and the external name for your printer profile. Application software vary in the use these names, which can be confusing.

It adds the date to the front end of the file name and automatically adds " " quotation marks around the file names.

It also enters "Argyll - copyright free use" in the copyright description and amends D50M to D50M2.

createprofile.txt

 

[pharmacist]

HI Emulator, how does this new batch file compared to the one I uploaded previously in terms of color fidelity and especially in the dark regions of the black&white printing ?

 

[Emulator]

Hi pharmacist, I am still getting problems, I think it will take a while to find a solution. It takes so much work to make comparisons. The dog leg at the Dmax seems to be common to most current profiles, but the cause? I see from other web comments, for earlier versions, advice to avoid -H in chartread for ColorMunki. I have not tried that yet.

I am also troubled by not being able to get the beep working in chartread .

I've just redone a 660 patch chartread and produced a diabolical profile, I think it is time for a cup of coffee.