Number for suggested patches for good icc profile.

[dgberg]

I have been working on building a set of new profiles for my new p5370.
Using an i1 Pro2 it is a pretty slow process although not too bad.
Did 3 yesterday with only 800 patches and the test prints look great. Did a 1600 patch test and could see no difference. So where is the point of diminishing returns. Not going to do 1600 if 800 will suffice.

[digitaldog]

Yes, there is a point of diminishing return IF (big if) the package that generates the patches does so over a portion of the color space necessary to profile said device. YMMV.

[Rhossydd]

There's certainly a law of diminishing returns going on.

This was discussed at length a few years ago here. From what I can remember it's a bit dependant on what software you're using.
With (X-Rite) Profiler there were a few 'sweet spots' with particular numbers of patches that gave the best number of neutral grays. Finding those just meant having to keep adding patches one by one until you saw a good set generated, easier done than written about.
 
For myself that ended up being just over a thousand, but that also fitted neatly on a single sheet of A4 for my Isis.

[kers]

My experience is the more patches the more you are able to print the extreme colours the printer can provide.
but 800 patches seems to be enough for the general print.

[dgberg]

Not sure I have the time or the patience to try what you suggest. I looked at The I1isis thinking that would be my fix until I saw the price. I looked at them about 5 years ago and they were roughly $3200 and total they are over $5000 with the XL model being almost $7k. Both of those are out of reach for me. I timed the last two batches with my I1Pro2, 10 minutes for 800 and 22 minutes for a two page 1600 patch. Very doable even with the dozen I have to do.
No one seems to to be keeping up with profiles. Very limited for my P8000 and no third party for my new P5370. Looks like I have my work cut out for me today and tomorrow.

[digitaldog]

The number of patches also depends on the device to be profiled. A digital press or similar will need differing patches and many repeated over the press sheet/target, ideally due to differences in color output over the sheet. It's not an issue with modern, high-quality ink jets, which most here are likely profiling. Again, lots of factors and YMMV.

[GWGill]

There will be a major difference between RGB and CMYK modes. CMYK typically needs a lot more patches (2 - 5 x).
In general it comes down to how well behaved a device is. The more consistent it is, print to print and at different points on a page, and the more predictable its colors are between patches that are measured (i.e. how well the printers behaviour matches the interpolation model being used by the profiling software), the fewer the number of patches needed. To a degree it will also depend on how the test patches are distributed - a good distribution may need a lot fewer patches than a poor distribution (i.e. equally spaced vs. regular grid), but this also depends somewhat on how the patch distribution fits with the the software's interpolation model.

[NAwlins_Contrarian]

As a total amateur and probably the least-expert person in the discussion, FWIW, it seems to me that the number of patches necessary to get a 'good' ICC printing profile depends on three things:
(1) how linear / well-behaved the printer + ink + paper + driver settings the combination at issue is;
(2) how 'smart' the software is about the areas where errors are most visible and predicting the printer's least-linear areas, and concentrating patches in those areas; and
(3) your personal standards of good.

I tend to suspect that if you had a (presumably mythical) totally linear printer, then theoretically you could get a good profile with 27 patches: every permutation of each of red, green, and blue at minimum value, midpoint, and maximum value.

I've been pleasantly surprised at how well the X-Rite software for my lowly ColorMunki Photo works by printing and measuring a standard set of 50 patches, analyzing the areas most in need of refinement, and then custom-building a second set of another 50 (for color profiles) or 100 (for B&W-oriented profiles) patches and printing and measuring those. But this is an iterative process (print-measure-calculate-second print-second measure-build profile), and the typical process (print-measure-build profile) is not. My sense, quite possibly wrong (and please correct me if so), is that more than a few profiles have been built with 'dumb' patch sets. E.g., a 1728-patch set can be built as a 12x12x12 matrix of the permutations of reg, green, and blue from minimum to maximum; and a 729-patch set as a 9x9x9 matrix.

I'm definitely not a master printer--far from it! I do have good physical color acuity, and a propensity to notice color issues that even others who can (if shown) see them tend not to notice. You experts' experiences and opinions on this would be much appreciated.