CHROMiX

How to get numeric comparison of two printer profiles

I have and i1Pro device and create my own printer profiles using i1Profiler. Just this week I purchased a new Epson P600 to replace my dead R2400 and I have gone through creating new profiles.

Now I am looking at the new profiles in ColorThink2 and comparing the 3D graphs with those from my Epson 7800 (AIS UltraMax II ink) and can see a noticeable difference in both the volume of the graph and the area of the 2D projection below.

Is it possible using CT2 to get a deltaE plot of the difference? This is quite frankly a little over my head in the technical side of color but a I really curious to see what that is.

tks, louie

Hi, Louie.

What do you expect to see ? The difference in how both profiles are mapping out-of-gamut colors? Or just “gamut volume”? Or the difference between some gamut-boundary colors?

If a/ then you need some reasonable set of high-saturation colors (RGB or Lab). But what is of interest for you ? In some print-houses we are interested in Pantone conversion, but I assume this is not for you.
If you have some set of colors … send them thru first profile. You will get “printers RGB colors” with different values. Take these new values and save absolute Lab coordinates. Do the same for second profile. Take Excel and compare them (simple dE = SquareRoot (LL+aa+b*b).

If c/ - the same as a/ but you source colors are not AdobeRGB, sRGB or Lab, but simple RGB values “assigned” to the printers profile and converted only to Lab (only 1 transform)

Most of that can be done even in Photoshop, but examining more than 15-20 color can be very inconvenient. :slight_smile:

Thanks for the ideas. As I understand your instructions they will give me the differences in colors between different profiles for selected colors. As you point out doing more that a few would be tedious.

However, what I am really after is how to evaluate quality of different profiles and I think I got sidetracked by thinking of this as a DeltaE issue but I have now learned that this is much more complicated than that. What really helped is to watch (several times) Andrew Rodney’s tutorial digitaldog.net/files/Not_All_Pro … qually.mp4. There he points out that perhaps the best way to compare profiles is through the use of wide gamut color references files and provides two excellent ones.

After making several test prints I realized that the color profiles that I was making using my i1Pro (original Rev. B) / iProfiler were really no better than the canned profiles from the paper/printer manufacturer. This was disappointing to say the least. The question then became what if anything can I do improve my workflow/process to make better quality profiles.

In my case I have two rely on custom profiles for my 7800 because I use the replacement UlltraMax II ink set from American Inkjet Systems. These have proved to be as good and perhaps better the K3 inks for about one half the cost.

After several long discussions with the helpful folks at Chromix I determined that my best plan of action was to sign up for their ColorValet service and take advantage of their in-depth experience in creating color profiles instead of upgrading to an i1Pro2 and trying to figure all that stuff out my self.

I have just received my first set of profiles back from ColorValet and I am happy to report that they provided excellent results when printing the wide gamut test images. I can even see clear differences between Perceptual and Relative rendering intents that were apparently hidden by the poor quality of the profiles I was previously using.

-louie

So you think its a complicated stuff ? You are wrong. It is even much much more complicated !!! :slight_smile: Wish I knew that couple of years before…
After 5+ years of study I think Im still touching surface.

One argument for all - every manufacturer (and they all are PRO!) has their own way/approach how to convert between color gamuts.