ICC Profile Evaluation Print ???

[Correct Color]

Kirk,

In answer to your original question: If I had to use only one file to evaluate a printer profile, it would be the Granger Rainbow.

Here's a little info regarding how I use it, including a link to one you can download:

Correct Color Commentary

I'll also point out the what-should-be obvious here that if you're really serious about learning color management, you'll be money ahead in the long run if you hire someone to come teach you.

Thanks for everyone's help- another piece of the puzzle and an educational process.

You're getting some good advice here, but keep in mind that you're getting it from people who have spent a lifetime learning this stuff. Trying to learn color management on message boards is about as complete an educational process as, say, attempting to learn to become a doctor by mail order.

Mike Adams
Correct Color

[keconomos@sbcglobal.net]

Hi Mike:

Grainger rainbow has been widely used since it was lauded in "Real World Color Management" in 2003. The authors; Fraser, Murphy and Bunting made the file available and did a pretty good job of explaining its use. I do appreciate getting your take on it.

I regularly use it on the RGB Profile side. It is an untagged RGB file- it has a wide color gamut especially compared to the CMYK gamut I work with on the prepress and proofing side. None the less it is still a useful visual reference although to not as great an extent as with an RGB profile because the gamut is reduced and areas posterized simply because of the cmyk conversion.

For CMYK prepress and proofing the Idealliance Digital Print Forms contain a lot of good imagery and targets for visual profile evaluation. They are very well designed- I especially like forms 3 and 4. Additionally measured evaluation of printed Idealliance characterization data sets can provide hard Delta E info regarding the quality of a profile's output.

On the matter of education- it is an ongoing process and even old dogs can learn new tricks. I started selling, supporting and training in Color Management as a dealer for Epson, ColorBlind, Kodak Colorflow and others in 1994 and haven't stopped since. I am not embarassed that I do not know everything, and always appreciate the process of learning more and gaining an in depth understanding. I love stepping behind the curtain- it help makes all the pieces of the puzzle fit together.

My Best
keconomos@sbcglobal.net

[Correct Color]

Kirk,

Grainger rainbow has been widely used since it was lauded in "Real World Color Management" in 2003. The authors; Fraser, Murphy and Bunting made the file available and did a pretty good job of explaining its use. I do appreciate getting your take on it.

Well, they did a reasonable job explaining how they used it. But that's not the way I use it.

I regularly use it on the RGB Profile side. It is an untagged RGB file- it has a wide color gamut especially compared to the CMYK gamut I work with on the prepress and proofing side. None the less it is still a useful visual reference although to not as great an extent as with an RGB profile because the gamut is reduced and areas posterized simply because of the cmyk conversion.

See, that's why I suggested if you're serious about learning color management, you might want to consider hiring a professional to come out and teach you. It's unfortunately possible to learn a very lot about color management online, and yet still not fundamentally understand it at all.

Yes, the Granger Rainbow Colorremedies has available for download--it's not the one I use but no matter--is untagged. The whole point is that it has no gamut until you assign a profile to it. Since it extends from 0 to 255 in R, G, and B, of course what it will do when you assign a profile to it is extend to the outer edges of the gamut of whatever color space you assign to it. That may be a very large gamut, or it may be a very small one.

And that's fine for proofing RGB devices by assigning their profiles to it as described in RWCM. However, that's not how I use it. And I'm not attempting to take anything away from RWCM by saying that either. It's a good book and just about everyone who's at all serious about color management has read it. However, it's getting a little old now, and it's actually pretty light on useful information regarding large-format inkjet. And I did make the assumption that if you're profiling in ColorBurst, you're profiling probably either an Epson or a VuTek, but an inkjet, regardless.

Believe me, there's a huge misunderstanding on the part or many who think they understand color management that the secret to properly profiling printing devices is can be found in the making of ICC profiles.

It can not.

Yes, there are better devices than others; better software than others; better charts and better methodologies to making good profiles and they're not inconsequential. But they're also just "wrench turning" so to speak.

Making a good profile involves creating the state of a machine, and then characterizing the machine in that state. It's the creating the state of the machine that determines how much of that machine's capabilities you capture with the profile, and how well you capture them. And that boils down to single channel ink limits, linearization, and multi-channel ink limits. As simple and as complex as that.

And while the Granger Rainbow as I describe using it doesn't tell a whole lot about linearization, it will instantly tell you if you've got any issues in the balance of your single-channel and multi-channel ink limits.

And believe me, I've been in many situations and seen many profile evaluation files over the years. And unfortunately, many of them can print out fine even though the profile itself might have some huge issues in this very area.

So, and again as I said, after visually inspecting the gamut of the profile, and after checking the curves in CTP, my next step is a soft proof of my own eval sheet which includes a Granger Rainbow. Any imperfections in its transition to black, and it's time to start over. And if there was only one file I could use for profile evaluation, the Granger Rainbow would be it.


Mike Adams
Correct Color

[keconomos@sbcglobal.net]

RE: Grainger Rainbow-

Well, they did a reasonable job explaining how they used it. But that's not the way I use it.

What you say on your site regarding evaluating with the Granger Rainbow is very similar to what they say in RWC. Regarding the color gamut- I misstated in technical terms regarding color gamut of the Grainger Rainbow being large (it is not defined until a profile is assigned- referenced by me correctly in this same topic on 07-18-2011 12:38 PM if you read it). However in terms of what you consider on your site as “GOOD” when evaluating the quality of a profile with a soft proof of the Grainger Rainbow – namely “no posterization, no untoward artifacts; and in particular very good transitions- these qualities are much more difficult to achieve in CMYK prepress spaces (my point.)

In spite of your addressing me in what I consider a disrespectful manner (you have no idea of who I am and what I know) - I will experiment with evaluating CMYK profiles with the GR to see what I think- for my own benefit.

To Mike Adams- Color Correct- something to consider:

It is often those that proclaim the loudest how much they know, that have no idea how much they don’t.