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

[soberprinter]

A new kid here.

A little off topic: unevenness and muddiness in shadows is a tough one. The individual colored inks and black ink densities and how they are mixed in the driver, added to how that paper reacts, is one of the reasons many of us have gone to a RIP driver over the OEM one. I won't say that results are THAT much better than the OEM driver (with a good profile) but it does offer you much more control in the difficult areas (actually all areas) before the profile is made. Getting the ink densities correct for the paper and then linearization instead of relying on a fixed set of parameters does make a difference. Remember: we're trying to squeeze that LAST little bit of quality out of our inkjets. Sometimes you have to sacrifice a little gamut or Dmax to achieve the best overall results.

The main problem here is that it adds another full layer of complexity before you profile...(and you thought Argyll was confusing).

I find Gutenprint, actually, WinGP, which is a Windows compile of the source code (it's a google project) works very well. WinGP only works with 32bit versions of Photoshop and GIMP......BUT IT'S FREE! Gutenprint works with Linux and some version of Apple OS....and it's FREE also.

You want to use up a lot more paper and ink experimenting, try a RIP.

 

[RogerB]

Specs please. Is Letter size OK? 8mm size patches OK? ...

I am assuming (maybe wrongly) that any target that can be read using CM can be read using an i1Pro, which has a smaller(?) spot size. I regularly read 8mm x 7mm patches so it shouldn't be a problem. However, before you send a target it would be nice to have the TIFF (orJPEG) file for the target so that I can print it for a "readability" test.

The reason I suggested this was to see if a target read using a different instrument would eliminate the dog-leg in the shadow region. This seems to be present in both Pharmacist's and Emulator's profiles and it isn't obvious whether it's a problem with the CM of something in Argyll itself. Do your profiles suffer from this dog-leg?

Incidentally, I am in the UK and I guess, from your use of Letter size, that you are in the US. Not a problem - just takes longer.

 

[RogerB]

View attachment 986

Thinking about it a little more, perhaps the best objective is to aim for a straight line between 100% L and Dmax, as shown in this image by the orange line.

This would give a linear grey gradation down to Dmax and would require Argyll aiming for Dmax=2.14 rather than zero. A point that Argyll should know from chartread.

Isn't that what the perceptual rendering does? Colorimetric aims to reproduce all in-gamut colours precisely, which your orange line fails to do.

 

[Emulator]

So we accept it as correct as it is and use perceptual if we don't like the colorimetric result in specific images involving darker blacks. I must try printing that B&W test image in post#71 again, in perceptual.

 

[Emulator]

If you use the batch file in post#92 to create a 750 patch profile, we can have a contest to see whose computer is fastest!

Use createprofile to run colprof and time it until the profile is produced. Mine takes about 14 to 15 minutes (a dual core), poor old thing.

pharmacist's takes, I think you said about 8 minutes, but that wasn't a 750 patch profile.

There isn't a prize, yet!

Only Argyll users will be able to enter.

 

[RogerB]

So we accept it as correct as it is and use perceptual if we don't like the colorimetric result in specific images involving darker blacks. I must try printing that B&W test image in post#71 again, in perceptual.

Perceptual rendering will certainly map L=0 to the printer's maximum black, but in my experience the linearity is never as good as the Colorimetric rendering - present examples excluded! BTW, for testing your greyscale print you may find the Northlight Imaging test image slightly more revealing. http://www.northlight-images.co.uk/article_pages/black_and_white_test.html

Following the possible comparison of CM and i1Pro, I've just tried a different approach. I used Emulator's excellent batch file to create the 750-patch target on a single A4. Unfortunately, my i1Pro would not read the chart successfully, with too-frequent "Too many patches" errors. I must say that I have never seen too many patches before - maybe something to do with the coloured spacers between patches.

I also printed a chart using 870 patches on 2xA4, measured it and created a profile, again using Emulator's batch file. The Gamutvision B&W response is shown below, and I must say that it looks extremely good, right down to Dmax. In fact, this profile, at least according to Gamutvision, is better than my previous 918-patch effort, even giving a (very small) increase in gamut. All credit to Argyll. So, it looks as if the strange behaviour in others' B&W response may well be caused by the CM.

Once again, many thanks to Emulator for sharing his batch file. Works like a charm!

 

[lowell374]

The reason I suggested this was to see if a target read using a different instrument would eliminate the dog-leg in the shadow region. This seems to be present in both Pharmacist's and Emulator's profiles and it isn't obvious whether it's a problem with the CM of something in Argyll itself. Do your profiles suffer from this dog-leg?

I thought the "dog leg" was due to the measuring instruments inability to measure a luminance of 0. That's why I use a DTP94 to cal my monitors (known for having very good low light noise response).

 

[Emulator]

Or is this due to the CM seeing stray light, as Mike was suggesting? I must try the matt black extra mask and mud flaps on the CM.

I have printed #71 again in perceptual, rel. colorimetric, saturation, and absolute colorimetric. You can see the differences, but I will let the prints mature overnight before I scan them and try to merge them into a single image for uploading.

Roger, did you measure the 750 creation time?

 

[RogerB]

Roger, did you measure the 750 creation time?

The i1Pro wouldn't read it with the spacers so I tried it with no spacers. I managed to read it, albeit with lots of re-reads, and generated a profile. Not the same paper - just a sample sheet of a coated paper that I happened to have. The profile is the worst I have ever seen! How do you like this?

So much for the i1Pro being better for small patch sizes. I think I'll stick to 2xA4 sheets in future.

BTW, Argyll generated this rubbish in exactly five minutes. Obviously didn't want to waste its time.......

 

[lowell374]

The i1Pro wouldn't read it with the spacers so I tried it with no spacers. I managed to read it, albeit with lots of re-reads, and generated a profile. Not the same paper - just a sample sheet of a coated paper that I happened to have. The profile is the worst I have ever seen! How do you like this?.

I prefer using -b, -A0.4, -P and -L as printtarg args. when using CM. The spacers are B&W and somewhat reduced in height. I had to experiment with the -A arg. inorder to achieve reasonable scans without too many errors. I also use -a1.1. This has allowed me to achieve 1024 patches on two Letter sized sheets. Really do wish I could get 750 patches on one Letter sized sheet as all you who are using A4 sized sheets. Sometimes I really think the U.S. is way behind the times as far as standards are concerned.