Claas, [Ahtung! Long message] You raised the most interesting question, "how far is it worth questioning the observable color differences"? If I was doing this for litho shops, I know I'd be glad to live with the difference I'm getting between the two printers, a difference nothing a printing press would not be able to match to a demanding client's expectations. Aber (But), since someone raised the question with me, and tested my humble expertise (indirectly), I'm tempted to hypothesize, as a good, amateur color scientist, that the difference that exists between the inks set, with the Magenta ink in particular, as William noted, *may* explain the small, lingering differences visible between the two outputs we see. It's possible. This would be an interesting analysis to make but I only have the IT874 for one of the two printers? I've seen my share of not so good color matching in my life and this is not bad color matching -- to my eyes (hard to relate to you in words the visual differences I observe between the prints?). I have to be willing to live with the small lingering differences anyone would get by using the same, basic ICC output profiling process. I find ludicrous the idea that creating the output profile across a number of profilers would make any differences, in AbsCol? And I'm not about to try it. "Trust the numbers" seems to be the bottom line. MfG / My two pesos / Rojelio (aka Roger Breton) -----Original Message----- From: Claas Bickeböller <lists@bickeboeller.name> Sent: Thursday, September 26, 2019 10:57 AM To: Roger Breton <graxx@videotron.ca>; 'colorsync-users?lists.apple.com' List <colorsync-users@lists.apple.com> Subject: Re: Slight color differences Hi Roger, there are some reasons that come to my mind: 1) The profiles do not represent the actual printer status anymore (or never did) - printer(s) changed after having done the measurements - measurement errors - inaccurate sampling of the individual printers’ non-linearities during characterization 2) Nozzle issues (which is basically another reason for 1) :-) 3) Out of gamut colours (unlikely with the combination you mention) Did you do a simulation of the result without printing? Is the dE-distribution similar for both printers? Just an idea to start digging into it. Best regards Claas

Am 26.09.2019 um 15:57 schrieb Roger Breton via colorsync-users <colorsync-users@lists.apple.com>:

Hi everyone,

I'm working on profiling two different Epson printers, a 7800 and a 7890.

Even though both printers are using the same, exact substrate, is it to be expected that there would be some "slight (but visible) differences" between the two printers? (I know I can't show you the prints.)

I convert from GRACol2006 to the 7800 and from GRACoL2006 to the 7890, using absolute colorimetry in both cases. Same conversion, same substrate, the only difference is the two printers.

In your opinion, what could account for the slight differences I observe? Is it possible (that's my best take) that the difference in the generation of inks used on both of these printers could account for the slight differences I observe?

Best / Roger Breton

www.graxx.ca

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