Max delta E to high

jbarrie

Active member
I am running GMG on a Epson 9900. I created my MX4 profile about 1 1/2 years ago and until now have been running just fine. Lately, when calibrating the Epson (with the GMG calibration wizard), my average delta E is fine (around .45) but my max delta E will not come down below 3.25. I have cleaned the print heads and have also performed a power cleaning with no improvement. After calibrating, I examined the information and 2 index color spaces are giving me the problems, they are: 100,100,100,25 and 100,100,0,75. What could be the problem and does anybody have any suggestions about what I should do about this?

Thanks
 
Those indices that take a large amount of ink can sometimes bounce around a bit (delta E wise) when re-calculating. You might try avoiding having the software recalculate them (delete the current measurement before recalculating the profile) and if the numbers bother you, manually editing/guestimating the CMYK values that will yeild a lower delta E. That said, a max delta E of 3.25 is really negligible, particularly for the very dark patches involved.
 
Paper properties or proof device conditions should have been slightly changed by the time. Start with creating a new MX3 file to get more optimized TAC and color gamut. Then iteration for MX4 might work better

I wanted to remind max delta E 6 is still in tolerance for validated proof
 
Paper properties or proof device conditions should have been slightly changed by the time. Start with creating a new MX3 file to get more optimized TAC and color gamut. Then iteration for MX4 might work better

I wanted to remind max delta E 6 is still in tolerance for validated proof

can i have whitepaper or certification that shows delta e of 6 is still valid so i can have better justification to our clients.
 
Dear ar17,

Delta E 6 is max value tolerance for measurered control wedge. Average Delta E of measured patches should be less than 3. Check ISO 12647-7. This part of ISO 12647 mainly lists values or sets of values, and their tolerances, of the primary parameters specified in ISO 12647-1, especially for digital proof printing.
 
I don't use GMG, so I would not assume that the dE method used for calibration would have to be the same as the ISO standard dE94 used when measuring a colour bar/media wedge (for example CIE2000 would report a lower dE number than CIE1994). Whenever dE is mentioned, it is always helpful to know what dE is being discussed.


Stephen Marsh
 
I'd humbly offer that the ISO path used DE76, sometimes called DEab. This is the default DE calculation used by GMG.

ISO world is working actively towards adopting DE00 (Delta E 2000)

Regards,
 
GMG does use delta E 76 (ab) by default, but It should be noted that the OP is referring to calibration...i.e returning the output device to a known baseline (via the .mx3 print calibration file). The ISO 12647-7 targets and tolerances would be relevant when comparing to the color profile analysis (.mx4/5/r) using a control wedge, but for the print calibration (.mx3), one would expect to hold tighter tolerances. In short, don't aim for an average dEab of <3 max dE<6 for the printer cal...too loose!
 
from my experience, it's likely to do with the paper. Only few paper manufacturer/model can guarantee a paper deltaE of less than one; and by looking at the two index color you mentioned, it seemed to do with ink absorption on the microporous coating. Interested to know the final finding.
 
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