Comparing printer profiles neutral output

[Mark D Segal]

Mark,

Thanks for the input, good to know.

.............  Is there anything between the i1Pro and i1iSis to facilitate this process?  ...............

Richard Southworth

None that I know of.

[John Nollendorfs]

You can buy a z3200 from B&H for $2499 that has a built-in i1 spectrometer. You get an automated spectrometer and great printer at 1/2 the price of automated i1!!!

Sent from my XT1575 using Tapatalk

[howardm]

Consider 'used'.  I got an iSis for $1k recently (not an XL but I don’t really care about that) on the auction site.

The only issue is that it doesn't like really thick overly textured fineart paper (I forget the specification right now).

What WAS odd is that I still needed to have my i1Pro2 plugged in in order for i1Profiler to be 'licensed' to make/save
the profile.  You woulda thought buying an iSis would 'include' that.

Mark,

Thanks for the input, good to know.

Someday I'll run the 10/9 1764 patch set, 5 letter size sheets with an i1Pro is no fun.  Is there anything between the i1Pro and i1iSis to facilitate this process?  I'd love to have one of the latter, but there's no way I can justify, and its purchase would probably initiate divorce proceedings.

Richard Southworth

[Alan Goldhammer]

For neutral tracking, I use a patch set of 95 neutrals, repeated 9 times then randomized. For the highest precision, I've found it necessary to randomize patches as the values have some degree of printed location sensitivity. Repeating each patch 9 times provides much improved statistics, and reduces the standard deviation of the mean by about a factor of 3.

I don't think Argyll can do repeated patch sets.  Normally when I profile I print out random patch sets and do two readings, reversing the direction of each line reading and then averaging.  This approach gives good consistency.  I could to the same thing with the B/W neutral set but of course that would give only two readings.

[Doug Gray]

The only issue is that it doesn't like really thick overly textured fineart paper (I forget the specification right now).

What WAS odd is that I still needed to have my i1Pro2 plugged in in order for i1Profiler to be 'licensed' to make/save
the profile.  You woulda thought buying an iSis would 'include' that.

Nope, it sure doesn't include I1Profiler! I almost didn't buy the iSis because XRite didn't include an I1Profiler license with it. Further investigation showed that a license for another spectro product was all that's needed.

The iSis comes with an I1Profiler disk you can install (or just download from the website). Without a license you can make charts, print, scan, and save CGATs files which you can then process with Argyll.

But you can also use a prior product's I1Profiler license. I have two. The one from I1Pro 2 Publish and an older one from ProfileMaker 5. The latter is embedded in a dongle and is a full license (including CYMK). The former requires the I1Pro 2 is plugged in and is fully licensed for RGB stuff.

It seems weird to me as well that XRite doesn't automatically include an I1Profiler license with their premier spectro. Possibly it's because the iSis is used with other company's profiling products, perhaps using rips. But who knows!

[rasworth]

Once again I've hijacked my own thread, but I'd like to go a little further on the validating profiles theme.

I printed a synthesized color checker, courtesy of Bruce Lindbloom (embedded Lab profile), thru the Doug Gray 8/7 890 patch set profile, absolute rendering intent.  I then used i1Profiler with my i1Pro uv cut to spot measure the 24 patches and compare against the original image (see attached image).  The results were favorable, although I should calculate delta e's to be rigorous.

Two questions:

1. Are these 24 patches sufficient to validate the profile color accuracy?

2. How can I semi-automate this process?  I do have a working copy of ProfileMaker, as I remember it has additional tools.

Richard Southworth

[howardm]

I think they're just being greedy #$^%&   

The i1Pro1/2 seems like it's more 'supported' in non-XRite products than the iSis.

And the dongle will cease to work on the next MacOSX release, right?

[Mark D Segal]

Once again I've hijacked my own thread, but I'd like to go a little further on the validating profiles theme.

I printed a synthesized color checker, courtesy of Bruce Lindbloom (embedded Lab profile), thru the Doug Gray 8/7 890 patch set profile, absolute rendering intent.  I then used i1Profiler with my i1Pro uv cut to spot measure the 24 patches and compare against the original image (see attached image).  The results were favorable, although I should calculate delta e's to be rigorous.

Two questions:

1. Are these 24 patches sufficient to validate the profile color accuracy?

2. How can I semi-automate this process?  I do have a working copy of ProfileMaker, as I remember it has additional tools.

Richard Southworth

Question 1 is something we'd have a real hard time knowing, because an image could be reproducing a huge number of unique colours (10,000s, 100,000s) and who's to say on the basis of a comparatively small sample size how large a sample is enough to represent the population. We can infer from industry practice and from our own testing how many patches, and at least as important of what values, we believe to be adequate for practical purposes. The 24 colours in the ColorChecker are really very well chosen and this tool has survived over many years; their overall gamut is usable for a large variety of inkjet papers without incurring OOG colours. There are industrial users who consider this target sufficient for various purposes. But the industry standards these days for control strips used in printing press quality/consistency control range from the 48 patches of the Barbieri strip, to the 77 of IdeAlliance. I was curious about the impact on dE readings of using a wider (but still in-) gamut patch set for high quality luster/gloss papers and constructed such sets as demonstrated in my article about Stress Testing the Printer Workflow on this website. I found that the average dE readings were a bit higher compared with the standard ColorChecker set, but not that far off. So again, the number of patches didn't differ, but the "gamut reach" did. I also have unpublished results for a 48 patch set I constructed which show similar outcomes. When you find that you're dealing in average dE outcomes of less than 1.0~1.5 (say dE76 which makes no adjustments for the non-linearity of human visual perception) and the standard deviations around the mean are small, whether these results are a little more or a little less it really doesn't matter much for a good many photographic purposes.

I have no views on your second question - I don't know.

[rasworth]

Mark,

I read "Stress Testing the Printer Workflow", found it to be very instructive.  I noticed your profiles were constructed using 1877 and 2371 patch sets.  Has your work provided insight into loss of output accuracy vs. decreasing patch set size?  I wonder if accuracy falls off proportionally, or is there some sort of "knee" based on the printer behavior?

Again, thanks for all your help, has aided me in gaining color management knowledge.

Richard Southworth

[Mark D Segal]

You are welcome Richard.

Between the 1877 and 2371 I found the latter performed slightly better on grayscale neutrality. Otherwise quite similar. I haven't tried correlating patch set size with dE results. Not enough data pairs to make it statistically useful.

[GWGill]

I don't think Argyll can do repeated patch sets.

You could certainly edit together multiple .ti1 files if you really wanted to do this...