CHROMiX

Eye-One Match Scanner Profile Accuracy

Hello,

I have been making scanner profiles using Eye-One Match and a variety of targets, including the supplied target and a chaotic TC9.18 RGB target.

Using any target, I find a color cast is introduced. My targets paper-white is 96.8 / /1.4 / -8.2, and I have a gray-strip that measures 66.3 /-0.3 / -0.6. All measurements have been done with an i1-Pro. When I scan the target, create a profile with a reference file created in Gretag’s Measure Tool, and assign the created profile to the scanned target, Photoshop’s info window indicates the white value as 99 / -1 / 2, and the gray as 68 / -2 / 4. The visual appearance, as well as prints, confirm this difference. (My monitor is profiled, also using the Gretag Eye-One Match).

I have contacted Gretag, and have spoken with Tech Support, but without any substantive answer for over 2-weeks now. They have acknowledged the question, but haven’t been able to tell me if this is within the tolerance of the profile software, is a problem with methodology, or inherent in the software.

I imagine it has to do with the “settings” of the profiling software, but Eye-One Match does not allow access to these. Gretag tells me the Profile Maker 5 uses the same algorithms and will construct the same profile.

Any thoughts? Similar or different experience?

Pertinent files can be downloaded at:

digital-illuminations.com/For_Barry.zip

Many thanks!

Michael Morrison

How are you using the TC9.18 for scanner profiling?

So you are saying that you are measuring your scan target to create a new/custom reference file, correct? Is your i1 equipped with a uv filter? Beyond that, the comparison you describe is usually an unequivical evaluation of the scanner profile performance…less the rounding errors that Photoshop introduces. Have you ensured any sutomatic settings on the scanner are disabled? What kind of scanner are you working with?

If you have Colorthink Pro, profile eval. is better and easier than the Photoshop method. Open the scanned RGB image in a Woksheet, drop on your scanner profile to derive Lab values, drop on your reference file (Lab values) and click the delta E button under Workflows and you’ll see a comparison of the two data sets. You can then click the “rpt” button under Colors to generate a report of average delta values, change the delta E formula, set the delta E tolerances for good, bad and ugly…pretty freakin’ nifty.

Hello,

I print the TC9.18 (chaotic) and then measure it using Measure Tool to get the reference file. I then scan the target (all color management off, Epson V700 scanner, using Epson Scanner driver), and clean the dust spots on the target. I then load the measurement file in EOM’s scan module, load the scan, and make the profile.

What I learned last night is that Measure Tool only makes an LAB report when it measures the target (even though “spectral” is checked in preferences), but that if I use the printer portion of EOM to read and save the target, it saves the full spectral data. If I then use this file for the reference file in the Scan module, I get a much better profilestill with errors as before, but much better.

I have the i1 Pro without UV filters. I have wondered about OBAs and their effect. Perhaps this is why the spectral measurement file works better? I don’t, as yet, know of a gloss paper without OBAs that I could use for printing the target. . .

I have been looking at Color Think for a while, but haven’t dropped the $$ yet. Perhaps I will have to. Does it allow for editing profiles? Or just evaluating?

Many thanks,

Michael Morrison

Why did you opt to use a printed TC918 for you input target rather than a photographic target like an IT8, HCT or the included Scan Target 1.4? Do you do a lot of scan of prints from your printer?

That said, just for fun I created profile using both Monaco and gretag ProfileMaker to see how they add up.

Here’s a portion of Colorthink Pro’s delta E report for the Monaco Profile…

Average dE: 0.48
Max dE: 1.73
Min dE: 0.07
StdDev dE: 0.29

Here’s the report from the gretag profile…using the nuetral gray option…

Average dE: 1.66
Max dE: 4.45
Min dE: 0.26
StdDev dE: 0.68

A notable difference, particularly in max delta E. Same RGB scan and reference file were used in profile generation. I’ve always prefered Monaco profiles over Gretag for scanner an output profiles.

ColorThink doesn’t allow for profile editing, mainly for evaluation…not just the profile itself, but the workflows where profiles are utilized

Hello,

Very interesting. Thanks! Did you make a profile with my files, or from one of your targets? If from mine, would you be willing to share it with me?

I have IT8, HCT, and the Gretag scanner targets. The IT8 and HCT are difficult to measure because of their size, and because are neither chaotic nor have contrast dividers. I have made profiles from all three, and have similar introduced casts.

Monaco profiler, eh?

Many thanks,

Michael Morrison

Email me offlist and I’ll see if I can whip you up a proflie for comparison to what your getting. It’ll probably have to be an IT8 or HCT scan…don’t think Monaco will support the TC918 as an input target

Hi Michael,

Hahnemuehle make a Matte paper called “William Turner” which seems to have low (or no?) levels of optical brightener. Yes, I realise you asked for a glossy paper recommendation, but maybe a matte paper would actually be OK for a scanner target? It would not give the blackest blacks (or maybe I should say dark greys;-) but it might help get you closer to your neutral grey objective. (I beleive that with an Epson R2400 the gamut is actually better in the low “L” values than their website’s profile suggests). I plotted the greyscale response and the paper white spectrum (Eye-One Photo measurements) here: printerprofiling.com/pages/graphs.html

Simon

Does your i1 have a UV filter installed? That can really mess you up sometimes.