RE: Custom profiling the epson printers
RE: Custom profiling the epson printers
- Subject: RE: Custom profiling the epson printers
- From: "Steve Lawrence" <email@hidden>
- Date: Thu, 2 Dec 2004 18:45:03 -0000
- Thread-topic: Custom profiling the epson printers
> This was sent by a customer of mine from Microsoft.
> Thoughts on his logic?
I'll answer in an oblique way that I hope you will find useful for any
non-Postscript driver. I'll discuss inkjet, but it's applicable to any
non-PS driver really.
As you may know the common OSs limit non-PS drivers to receiving RGB
(and mono) data only. The driver is therefore always separating that
data to the n-channel (CMYK, light inks, HiFi inks etc.) data required
by the printer. The small handful of inkjets that can receive RGB aside,
this separation will always take place, it has to. That's an important
point to remember when considering the colour controls the OEM provides.
In theory, when creating an RGB profile to be used with application
level colour management you are told to turn colour management off.
However if the OEM provides such a control, the colour separation will
take place (as stated it has to). What level of internal colour control
occurs at the same time depends on the OEM. For example does it use a
simple colour separation algorithm vs an advanced one (that would
require source, destination assumptions etc), or limit inks for example?
If too little internal control is applied you can end up with a print
that can cause characterisation issues on certain media (too much ink
etc), yet at the other end, apply too much and the assumptions made
might be suboptimal for your configuration for different reasons.
So what's the solution? Well the answer is in using verification to get
the printer running optimally, because, of course, the quality of your
characterisation and final output is going to depend on that. Print step
wedges of at least the primary and secondary colours using the obvious
colour controls to see which fit your tolerances (grey balance,
linearity, colour gamut etc). Try that with colour management on and off
at least. You should find you'll get different compromises. I recall
this being well explained in Real World Color Management.
So in terms of process, there really is no right or wrong with regards
colour controls. It's perfectly valid to profile a non-PS driver with
colour management on or off, or using a different media setting for that
matter if it works for your configuration. The right way, is what ever
is right for your tolerances and your printer configuration. The only
thing to avoid (unless you really are stuck for a setup that is right)
is characterising using colour controls that are dependent on the input
colours, e.g. automatic image enhancement/correction controls.
Hope that's a help. Time for me to go home!
Steve
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