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As part of my experimentation I wanted to see how good the Argyll profiles were, using an objective method. To do this I modified a 288-patch profiling target so that all the colours were within the gamut of my printer, with a good proportion of them on or near the gamut boundary. I then printed...

First I'd like to thank pharmacist and Emulator for their work in this area that has encouraged me to take a closer look at Argyll CMS. After some experimentation I have decided that a chart on 2 A4 sheets give the best results with my i1Pro and I am now using a chart with 1058 patches. I can...

Unfortunately(?) these look very well-behaved - no nasty kinks or dramatic changes in gradient so I'm afraid they don't tell us much in this instance. Not sure what you can do now, except generate another 750 chart using bigger patches to see if the dog-leg is still there.

Just for the record, I printed my standard i1 target after scaling the patch sizes to be the same as those in Emulator's 750 patch Argyll target. Reading this target with the i1Pro using the x-Rite driver is easy - no errors whatsoever. So, maybe Argyll doesn't do such a good job with the i1Pro...

If you select "None" as the rendering intent in Gamutvision it will show you the intrinsic response of the printer, or at least it will show a closer representation of the measured data, unmodified by the profile.

Oh dear..... Have you completely ruled out the possibility that it may be a characteristic of your printer/ink/paper combination? In other words, is Argyll trying to tell you something? What does the B&W response look like with no colour management?

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...

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...

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

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...

It may also be interesting to compare the results from the same target read using an i1Pro. That might answer the questions about possible hardware limitations when using the CM. Anyone care to send me their target?

Exactly!

I can feel a case of Post-Argyll-Stress-Disorder coming on here! My experience is that more patches can produce better profiles but that the "better" profiles don't necessarily give better prints. The vast majority of the profiles I have made have been from 918 patches and for a well-behaved...

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...

I deliberately left the scaling the same between the two plots to make the difference easily visible. Had I reset the scale it would have looked like this. Still not much of a clue to the poor print quality. I'm not saying that the Round Trip isn't useful, just that it doesn't tell you...

I'm not sure that these Gamutvision analyses are showing what you really want to know. By using the Round Trip view you are invoking both the AtoB and the BtoA tables. This may test the internal consistency of the profile but doesn't necessarily tell you about the accuracy of the printed output...

Yes - more helpful I think because it shows that the anomalies are primarily dark regions rather than "holes". Shows the usefulness of a tool like Gamutvision if you're messing around with profiles. A test print doesn't always show this kind of thing straight away. in reply to rodbam and The...

They don't have to look that bad! Just curious to see if yours really had a hole in the greens.....

It would be interesting to see a print of the Grainger Rainbow. The Gamutvision result suggests it might be a little bit "rough".

Have you looked at QuadToneRip? Assuming your printer is supported it's by far the best way to control an all-black ink set.