GMG, Epson, or User Problem?

eran

Well-known member
I recently identified an issue with my 7880 in which it's two color red and magenta were far from achieving ISO spec. Prior to this instance, I've not really had to delve into Colorproof or the MX4 that was set up by my predecessor.
Needless to say, I've been learning an endless amount about my software but I've run into one problem that I cant seem to get around... to make matters worse, It seems to be the root of my red issue.

Magenta.gif

I found an earlier post that seemed very similar and the problem ended up being a faulty measuring device. Taking that into consideration, I've attempted using my i1 instead of my beloved Isis only to find the same results.
Most of my profile achieves acceptable deltaE; the only exception being the colors that rely heavily on magenta.

Any ideas of where I might be going wrong?
Could this be a device failure of some sort?
 
I don't believe your MX4 is bad (unless you are using the wrong one.) First make sure your 7880 is shooting ink the way it is supposed to, perform a nozzle check. If the nozzle check passes next run through the GMG calibration wizard (adjusts MX3.) This is the iterative step that lowers deltaE and keeps your proofs consistent. If you can't achieve a low deltaE on your calibration your consumables would suspect (ink & paper.) First and foremost though, make sure the printer itself is in good condition and you are using the MX4 that was used when you created your standard in Proof Control.
Best regards,
Todd
 
Thanks for your reply, Todd.
I'm fairy religious on running the nozzle checks... always before running a calibration set. When I ran a calibration with my i1 (as opposed to the isis) the first iteration failed, and checking the statistics revealed a deltaE difference that basically reflected what my MX4's were unable to correct. I was able, with a few iterations, to pass the calibration. With high hopes that the difference was a failure of the isis, I began iterations on a fresh MX4 with the i1 (ugh!) The results of that experiment are reflected in the screen shot. I really thought there was some sort of malfunction with the isis but that doesn't seem to be the case.

I don't understand how every screen value of magenta can come out so good and then 100% be so far off.
 
Hi Eran,

How did you derive your target data? Your 100% magenta target is L*=45.41, a*=70.71, b*=-7.91. ISO 12647-2 for #1&2 paper is L*=48, a*=74, b*=-3.

As far as why your not achieving your target value...i don't think there's enough info to make the call, but based on the CMYK color values, it doesn't look like you'll hit it. There's a significant amount of black and 100 % Magenta in there already. Magenta on our printers is achieved with no black at all. What are your separation and key settings (on the common tab)?
 
Thanks Meddington.

The target is derived from a profile of one of our presses. I suppose that may have been something worth mentioning. I've been experimenting with different target data, initially with pulling the LAB values from the xrite published Gracol profile... the results were ultimately the same though.

The MX4 is set up in "Inket" separation mode with key settings of 0% minimum and 90% maximum.

I must admit that I don't fully understand the "key" references of GMG. I'm experimenting with upping the maximum value now though... I noticed that my MX3's gradation values are all very specifically set.
Is that something done by the calibration process or possibly something done when the machine/software was set up?
 
I set my key settings to 0% & 100% for extra latitude in case things need to move. I cannot say that I fully understand the MX3 gradation values, but I believe these are set as one of the first steps when you set up the printer. I agree with Mike, there is a large amount of error to eliminate. Did you iterate your MX4 (calculate with target and current measurement?)
Again... you're sure the printer is functioning properly. I have run into similar issues after techs have been here doing maintenance. After one such visit a simple head alignment solved the problem.
Best regards,
Todd
 
Thanks again, Todd.
I saw some improvement reflected in deltaE after setting the keys to 95/0 so I may have some more experimentation to do there. I've certainly not ruled out the possibility of machine failure but I also feel I need to be fairly certain I'm not messing anything up... The results represented in the screen shot are after four iterations but I've ended up with the same poor values after eight iterations just the same... even to the point where Colorproof begins giving me errors that certain values cannot be further improved.
Hrm...
 
Hi Eran,

Our key settings are 0 and 90% as well, and I haven't experienced the issues you are having. I've read on other forums that performing a head alignment as mentioned by Todd solves a lot of issues.

In one of your posts you mentioned that it took you several iterations to pass the MX3, which has seldom happened to me. One thing I noticed is a nozzle check looked fine, but if I ran a "Check and Clean" from GMG some of the colors were missing blocks of color. If I my calibration fails I usually run that instead of a nozzle check.

I don't know if you have GMG tech support, but Kevin and Chris are pretty helpful.

Jim
 
Hi Jim,

I'm not familiar with the "Check & Clean" function. Is that performed from Colorproof?
 
Yes Eran, double-click on your specific printer in ColorProof. It's located directly below "Print Nozzle Pattern" in the Utility section.

Jim
 
What paper are you using, and what under what ink limiting was the gamut file created?

At the 85% magenta index, your color values are already pushing 97% magenta, so its no wonder that the 100% patch cannot be achieved. The software is attempting to get a higher a* value by manipulating the C, Y &K channels, dropping cyan out completely, but it just isn't enough. It also has to lower the L* value, and is adding black, which i likely not helping the a* value. Unless you can push a higher ink limited gamut file with this paper, I don't see this being achievable.

I must admit that I don't fully understand the "key" references of GMG. I'm experimenting with upping the maximum value now though... I noticed that my MX3's gradation values are all very specifically set.
Is that something done by the calibration process or possibly something done when the machine/software was set up?

"Key" references here are refering to black generation within the profile. Starting point and limit.
The mx3's gradation values are preset for a given printer/ink/paper combination, though they are often applicable to many different substrates. Not really something you want to edit.
 
Prior to this instance, I've not really had to delve into Colorproof or the MX4 that was set up by my predecessor.

Eran, can I ask a stupid question? Were all the MX3 and MX4 files set up for the 7880, or were they originally done for maybe a 7800 by your predecessor?

Otherwise it sounds like you may need to start from scratch, including the ink limiting stage as Mike suggested. When I have talked to GMG support, they have said that only a few iterations are needed to get to a good MX4 file.

Jim
 
Excellent. Thanks.

(oops... didn't realize we this had spilled on to a second page!)
 
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I'm using Epson Premium Semigloss with the 285 ink limiting gamut provided with the started kit. All of the original MX3/4 setup was performed during the intital training when both the proofer and the rip were installed a new. All I have to go by (as far as original setup) is my predecessor's notes which were taken during her training with Xpedx. I would have to assume that would mean the setup was done by the book although some of the notes are a bit ambigious... making it hard to start fresh.
 
Mike & Jim have some excellent points. Maybe you should have GMG support talk you through the set up process? You could just redo your gamut file as a start, that's not as involved as a total tear-down.
Best regards,
Todd
 
That does seem to be the logical place to start at this point. It's time to kick myself though as I made the call to not renew our service contract with GMG as I thought the system was going to be self sustaining. *sigh*
 
Update!

Update!

I've been putting off calling support in hopes of solving this myself and I've found that I can get my MX4 into tolerance but it requires using a full gamut file. Building a new gamut file utilizing one of the starter kit ink limiting profiles seems to inherently clip my color space too hard. I know this method can't be ideal but I have to admit that I'm not entirely sure why...

That said, I beseech you all for your advice once again. What repercussions will I bear for my actions?

Thanks again, as well, for all of your help thus far. I really appreciate it.
 
That said, I beseech you all for your advice once again. What repercussions will I bear for my actions?

You may have proofs come out not entirely dry to the touch, or even runny ink with a linear gamut file. If this isn't occuring, and it would likely be evident on a profiling target, you might be fine (assuming there are no other "gotchas" you haven't discovered yet). Keep us posted.
 

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