Ink Limits

[sjm]

OK enlighten us. See Jasonx's post earlier.

 

[Rooster]

No, I'm going to wait for you to enlighten us this time. I'm not playing that game with you anymore.

 

[JR Digital]

what are we in 6th grade?

 

[Hanzo]

It's amazing how little information you actually contribute to these threads beyond just calling other peoples information into question.

What question are you actually referring to in your last post? I've seen no wandering off topic in this thread by anyone except you.

I thought that eye4color's method of using the chroma values from the LCH readings to determine the maximum saturation point of the hue was rather ingenious. You're either just not getting it, or you're just baiting people. After going through this a few times with you now I'm leaning towards the latter. It would seem you're far more interested in pushing people's buttons than contributing anything useful.

eye4color is not being ingenious, he's trained and is clearly color literate. Many people measure ink restrictions by eye (some even through a loupe). He's right, measuring chroma is the most accurate method. Now the question is, what chroma values are you aiming for?

 

[eye4clr]

eye4color is not being ingenious, he's trained and is clearly color literate. Many people measure ink restrictions by eye (some even through a loupe). He's right, measuring chroma is the most accurate method. Now the question is, what chroma values are you aiming for?

True, nothing innovative on my part. I learned from others that are much smarter than I.

What chroma? I'd say the biggest you can get with some consideration given to the gray balance of the CMY.

There was one guy I worked with that did ink restrictions by holding a Pantone book to the individual C, M, and Y. As a result, he never got more gamut than Pantone process CMYK can give. I like knowing that I'm getting the most of whatever the process.

Oh wait, there is the situation when you're setting up a proofing system. Then you have a chroma to shoot for based on what you're trying to emulate. I still always feel compelled to throw a bit extra in there just for wiggle room on the overall gamut.

 

[Hanzo]

There was one guy I worked with that did ink restrictions by holding a Pantone book to the individual C, M, and Y. As a result, he never got more gamut than Pantone process CMYK can give. I like knowing that I'm getting the most of whatever the process.

Damn, never thought of doing something like that, but its pretty ingenious as a reference. Unfortunately, Pantone charts have a shelf life, so I wouldn't recommend it.

My partner and trainer told me that ColorBurst uses chroma based limiting, which is something not many RIP vendors suggest, and also use the G7 method. The results I've gotten are great, generating profiles with a dE CMC of 0.44

 

[Bly]

Eye4clr is the man here. He taught me a lot about profiling, in particular setting ink restrictions by chroma. Good to see your input on this forum man.

 

[eye4clr]

Damn, never thought of doing something like that, but its pretty ingenious as a reference. Unfortunately, Pantone charts have a shelf life, so I wouldn't recommend it.

I never used the method myself. I prefer to read the chroma directly. Especially since I don't setup proofing systems these days, only straight production for me now.

 

[Jeff South Florida]

Eye, I have always used a reflective densitometer from the press room. At first I would match the CMYK to the pantone book as mentioned. I then realized that the profile could not make the gamut bigger than the in limits would allow. I now get the most density out of the color before it peaks. Is this similar to what you are doing but I have the privelage of a densitomiter?

 

[Bly]

Eye, I have always used a reflective densitometer from the press room. At first I would match the CMYK to the pantone book as mentioned. I then realized that the profile could not make the gamut bigger than the in limits would allow. I now get the most density out of the color before it peaks. Is this similar to what you are doing but I have the privelage of a densitomiter?

Eye4 uses a spectrophotometer, the densitometer's more sophisticated brother.
You can't measure colour with a denso, just darkness.

 

[Hanzo]

I never used the method myself. I prefer to read the chroma directly. Especially since I don't setup proofing systems these days, only straight production for me now.

One more thing about Pantone charts: they're printed on an offset press with offset inks and coated/uncoated stock -among other things... And we're using large format devices with solvent, eco-sol or UV inks on either vinyl or banner... Definitely not the best reference. Chroma should be read directly on the surface, I agree 100%.

Bly: a spectro measures spectral data, it gathers complete color information, which can be translated into colorimetric or densitometric data, and its the most complete instrument available. A densitometer just measures the strength of color (density).

 

[eye4clr]

Restrictions can absolutely be done with a densitometer. The downside is that the density continues to ramp up after the chroma (gamut) tops out. So what you'll get is excess ink use for the same end gamut.

Let's keep things in perspective here...the "excess" ink by doing restrictions via density is really not a game changer, it's pretty minor in most cases. But for those marginal medias or if you're trying to drive your system fast, every bit of excess ink is an obstacle.

Besides, if all you have is a densitometer, you're not making your own ICCs. So, all you'll be able to effectively do is the restrictions and linearization. As long as you have good grey balance and run only CMYK files that are suited to that grey balance, you'll be fine. You won't be accurate, but you'll have some nice "poppy" very sellable color.

Just don't come whining when your pantones are off or an RGB file slips through and looks like poo.

 

[Rooster]

I've always just used my eyes to determine the max chroma value. However using the older X-Rite DTP41UV strip reader it's more of a pain to read individual patches.

I really like the chroma based limiting of the colorburst RIPs I've used. It prevents you from resetting your linearization curves to a lesser gamut situation. ie: if your new linearization curves don't produce the same densities (which would throw off your profile) it voids the results and prompts you to readjust your ink limits or in a worst case reprofile. Very intuitive.

 

[Bly]

Rooster, I use X-Rite's Colorport app to read LCH values for ink restrictions with my DTP41.
http://www.colorxact.net/content/view/39/262/lang,en/

 

[Rooster]

Cool thanks!

 

[Neil]

Good one Bly.
It's gotta be better than the old Gretag Colorlab program I've been struggling with!

 

[eye4clr]

I was checking out Bly's link and noticed something I've never seen before....

"you can upload in the colorXact online-profilation-tools"

What is profilation? Sounds like something my wife used enjoy but now refuses to do for me.

 

[Bly]

Good one Bly.
It's gotta be better than the old Gretag Colorlab program I've been struggling with!

Not sure how effective it is really mate and it doesn't give the Delta e but it's better than the old squint and shoot approach I used to use.

 

[Bly]

You should try buying her flowers Eye4, and if that fails an expensive overseas holiday usually does the trick.
I just took my wife to Thailand, never saw so much action from her - since she wanted to keep me out of all the brothels that are on every corner.

 

[sjm]

Not sure how effective it is really mate and it doesn't give the Delta e but it's better than the old squint approach I used to use.

Hehe, which delta-e formula are you using?

Wait let eye4clr reply, said in jest.