Proofer gammut vs GRACoL

[jstotz]

I'm in the process of calibrating my proofer (HP Z2100) and I've noticed that when I compare the 3D gammut of the baselin'd but uncalibrated proofer with that of the GRACoL data set, some of the GRACoL gammut is outside the proofer. It is most apparent in the yellow and orange areas. Specifically, the ridge formed by the yellow step scale is more to the left (smaller a values) in the proofer gammut and more to the right (larger a values) in the GRACoL gannut. In the proofer gammut, the yellow ridge curves to the right, so the yellow midtones have lower a values than the lights or solids. When he profile is made, the resulting GRACoL proof has magenta added to the yellow (which makes sense) and the yellows are darker (lower L) than they should be, because the resulting yellow values have slid down into that valley between the two yellow ridges in order to stay within the common gammut space.

Here are some sample numbers:
Proofer
100Y 87.54L -2.45a 104.80b
50Y 92.31L -9.17a 52.09b

GRACoL
100Y 88.94L -5.02a 93.17b
50Y 91.66L -3.87a 43.57b

Is this something that others have noticed, either with this particular proofer or with ink jets in general? Is it a problem with the paper, not allowing enough ink to push the proofer gammut up high enough to encompass the GRACoL gammut?

[TerryWyse]

I would first look at the media you're using...next would be the ink-limiting in your RIP (perhaps limiting too much?). Best chance at getting the maximum gamut out an inkjet is to use good quality paper that has an L* in the 95-97 range plus the ability to "hold" ink well without mottling.

Out of curiousty, I just measured a solid yellow patch from my HP z2100 on Epson Proofing Paper White Semimatte and I came up with a chroma of around 104....very similar to what you've got. While I love the HP z2100, my Epson printers (9600/7800) can pretty routinely get solid yellow chroma numbers in the 110 range.

It's a fact of life that, despite the "wide" gamut of inkjet printers in general, many of them will have a hard time with the orange/red/magenta region of the GRACoL gamut.

I would start with a change of paper.....I can recommend both Epson Proofing Paper White Semimatte and Epson Standard Proofing Paper (240) as two very good papers at a reasonable price...and they both work fine on the HP z2100. On the HP, you need to make sure that you're using a starter media type that lays down the maximum amount of ink. Use that as the media type when creating your custom media setting. Then you can use your RIP ink channel limiting to dial it back a bit if needed.

Terry