Paid profiles exhibiting unique weirdness: banding & color shift

[GWGill]

For those who have been using spectrophotometers for a while now: is it possible for the lamp to age, and induce a color-shift during reading? Could there be any other kind of issue with their hardware that might cause this?

Lamps do age, but that's what the calibration tile is for and why you calibrate it before you use it. The long term accuracy largely depends on the stability of the reference tile, and the stability of the optics with regards wavelength (which is why the i1pro2 does a wavelength calibration as well as white tile measurement).

I have seen some other effects in older lamps such as a "memory" or "warming" effect where the recent on/off timing affects the current reading more than usual. I'm not sure if that's something peculiar to the particular (older) instrument I was looking at, or a consequence of lamp aging though.

[tvalleau]

Thanks. I appreciate that bit of knowledge.

[tvalleau]

non-update: I said I'd have profiled the Epson paper by today using my new i1Pro2 today, but I lied. The device didn't arrive until this morning, and I have a meeting tonight. Mañana...

[tvalleau]

Well, I broke out the new i1Pro2 and stumbled thru my first printer scan. (I say stumbled because a) the instructional videos are 4 years out of date; 2) starting in "basic" mode seemed appropriate for a newbie to this particular hardware, but I went down the rabbit hole by trying to adjust the patch sizes (after getting a warning their own (!) default sizes were too small.

Finally, I gave up and just did a MO default all the way across the board, (800 patches) and it scanned perfectly. (In fact, having done this kind of thing with different hardware years ago, I'd have to say I was impressed at how well it performed: I didn't mis-scan a single line.)

OK: so much for the back story. It's time to cut to the chase...

... I printed the same image on the same paper using my newly created profile, and relative colormetric rendering intent... and it looks perfect. The cyans are the correct tone and the "banding" (the "C artifact") is completely gone.

Dropping my new one, and the old paid one into CT, I can see that mine is larger, particularly in the green/blues and generally overall.

So, now I have Epson's profile; my own ColorMunki profile (sold the CM yesterday, now that I have an "oooohhhh shiney" serious tool) and today's newly created profile. None of these exhibit the original issues with RC intent. Only the paid one is wrong.

Everyone here would recognize who did the paid profile for me (and some of you may have easily found it out.)

They are fine folks, and I'd like to pass this along to them, but at this point, the only conclusion I can come to is that there is something wrong with their profiles (since every one exhibited the same RC issue, to a greater or lesser extent.)

Does anyone here have any further comments, before I head off to recreate my profiles (for an exhausting -third- time now) ?

Thanks to everyone for your interest and advice.

OH... and if anyone has tips I might use for my new i1Pro profiling (I'm hand pulling the scanner; just can't afford the automated toy right now) I'd love to hear them as well.

Once again: thanks.

Tracy
www.valleau.gallery

[Jeff-Grant]

With the old i1Pro, hand scanning was always a problem for me but something has changed a lot. I rarely get an error when scanning a target now. The old i1 was so bad that I bought the io table. It was that or give up profiling. The new device also seems to give more consistent results.

I'm sure that wiser heads will comment but 800 patches sounds way too few. I scan 2000 patches which is 3 A4 pages. My understanding is that around 2000 is where more doesn't help. I also save my scanned data as PM5 txt which makes it easy to drop into CT.

[digitaldog]

I'm sure that wiser heads will comment but 800 patches sounds way too few.

Even the old TC918 target can build a very good profile. Heck, with as few as 100 (50/50), ColorMunki is darn impressive. Sure, use more, but that doesn't mean, depending on the behavior of the device, 800 patches will suck.

[tvalleau]

Thanks, Jeff. As I explained, this was my first hand scan with the new equipment, so I used the most basic setting the (new) software supplies. That, and I wouldn't think that more samples would cause the negative effect I've reported.

Yes, that said, when I'm making "real" profiles for daily use, I'll use more patches. I just wanted to quickly see if the problem remained.

It did not.

[Jeff-Grant]

Even the old TC918 target can build a very good profile. Heck, with as few as 100 (50/50), ColorMunki is darn impressive. Sure, use more, but that doesn't mean, depending on the behavior of the device, 800 patches will suck.

I thought you would answer, Andrew. My understanding is that 1000 to 2000 patches is a good number but I got that a while back. Does that still hold? I understand that a good profile can be had with less but, at what point does more stop improving the result?

[digitaldog]

I thought you would answer, Andrew. My understanding is that 1000 to 2000 patches is a good number but I got that a while back. Does that still hold? I understand that a good profile can be had with less but, at what point does more stop improving the result?

It depends, sorry. But the point is, 918 can work. I'd probably agree, something around 1000-2000 is a sweet spot. Depends on the software building the patches too, they are not all equal. There's a point of diminishing return. So let's say, 1500 or so.

[tvalleau]

To "choice of software" I'm using i1Profiler 1.6.1  (XRD version 2.3.8.19)

...if that matters...

[Jeff-Grant]

It depends, sorry. But the point is, 918 can work. I'd probably agree, something around 1000-2000 is a sweet spot. Depends on the software building the patches too, they are not all equal. There's a point of diminishing return. So let's say, 1500 or so.

Thanks Andrew. I just went hunting around and found the Bill Atkinson profiles that were so popular a while back. Are they still a good choice or are the i1Profiler generated charts a better match these days. My memory is that they were highly regarded at the time.

[hugowolf]

...
OH... and if anyone has tips I might use for my new i1Pro profiling (I'm hand pulling the scanner; just can't afford the automated toy right now) I'd love to hear them as well.

I have found, at least on fine art papers, two sheets of full patches, and one sheet of optimization patches, produces more accurate profiles than four sheets of original patches. There is no increase in gamut, but better linearity.

Brian A

[tvalleau]

Excellent, Brian. Exactly the kind of useful tip I was looking for.

(Having heard no more here, I'll be pointing the folks who did my paid-for profiles as this discussion... and asking for a refund.)

I'm sorry that there was no gain in knowledge (for the group) to be had from this little adventure, but my thanks again for the courtesy from everyone here. 

I'm off to see the Wizard   

[tvalleau]

Well, it's been a while, and I thought it was time I round out this topic, since I started it.  A few weeks ago, the company sent along a second profile for me to check, and the banding simply changed places, and (interestingly) moved to a new color. I offered to continue helping track down the problem, but  they "went silent" - so I suppose they think it was something applying only to me, or just plain lost interest. Maybe it was me; maybe the other who may use their service simply don't have, or never saw, the issues I reported with RC. The company did, at my request, refund my profile subscription fee.

I'm perfectly happy with the i1 Photo Pro, scanning 1600-patches for each profile, and the results only make me wish I'd done this years ago.

Thanks once again for the interest,  help and courtesy. Best wishes to one and all.

[GWGill]

With the old i1Pro, hand scanning was always a problem for me but something has changed a lot. I rarely get an error when scanning a target now.

The i1pro2 has a tracking ruler (technology borrowed from the DTP20 presumably), primarily to match the two passes when you do a UV scan (to compute M0, M1 etc.), so if they use that for normal scanning as well, the patch recognition should be more robust.

[tvalleau]

I believe the company is using an i1iSis to generate the profiles (from an 800-patch chart.)

I, on the other hand, print out the 1600 patch and using the sliding ruler setup you mention, can turn out a profile in about 10 minutes.

[Jeff-Grant]

The i1pro2 has a tracking ruler (technology borrowed from the DTP20 presumably), primarily to match the two passes when you do a UV scan (to compute M0, M1 etc.), so if they use that for normal scanning as well, the patch recognition should be more robust.

Thanks Graham. It is a vast improvement of the original.

[tvalleau]

FWIW, I did notice a significant increase in i1Photo Pro reliability (of the passes and calibration) when I replaced the bundled USB cable with a better one. YMMV.