Mike Chaney's Tech Corner

Driver settings.

What is technical difference between -

ICM ticked and no color adjustment ticked.

and

ICM Ticked
No color adjustment unticked
ICM Mode with  Host ICM selected

Host ICM selected appears to give slightly better print, generally lighter with more fine detail.

Jeff

Jeff,

No color adjustment is where the Application (QU in our case) manages the colour. The printer profile is specified in QU and the driver does nothing in terms of getting the correct colours on the print. This is "proper" colour management - you do need a good printer profile that matches your printer, ink and paper type.

ICM Mode is where the driver manages the colour and QU is also set to "let printer/driver manage colour. I don't know what other printing applications are set to for this. QU does use a special do-it-all profile when this is set, I've always been a little vague about this!

My R2000 printer has a basic and advance ICM mode, the latter allows you to set the input profile and rendering intent. I don't often use this mode so have never experimented. I suspect your R1900 driver has similar settings.
It also allows you to use the "Host ICM", that I believe, is using Windows (= host) colour management, not the driver, so "ICM Mode with  Host ICM selected" is the same thing.

I hope that helps - we need a guru for the detail (Mike?)

Terry

There are two basic modes.  The first is the most straightforward: set the driver to "no color adjustment" and supply the printer profile name in QU.  Then QU does all the color work and the driver is running "raw" and does nothing with color.  In this scenario:

(1) QU converts color from the image's color space directly to the printer profile: image color space --> raw printer RGB values
(2) QU sends that pre-profiled data to the driver
(3) The driver prints those raw RGB values (which have already been massaged to the correct values in step 1).

The second option is "Host ICM": with that option you set QU to "Let printer/driver manage color".  In this case, QU uses it's built-in pRGB color space which is big enough to encompass the gamut of any printer.  In this scenario:

(1) QU converts color from the image's color space to pRGB
(2) QU sends that pre-profiled data to the driver and sends pRGB as the color space (hence the term "Host ICM": the "host" specifies the incoming profile)
(3) The driver does a second conversion, converting from the incoming pRGB to the built-in profile for the currently selected media type

Regards,
Mike

Many thanks both.  Very interesting.

I was doing some prints using a PermaJet custom profile, and using the Qimage updated Live View, Queue and Settings somehow got Host selected and was surprised to find a print improvement especially in the blue sky and green areas.

Did two prints on same piece of paper side by side and difference was very obvious - better with Host.

The R1900 is on the way to the scrap heap, one print and it gets air in head and requires a full clean - gobbling up ink.

Will probably follow Fred and get a Canon 100s

Jeff   

Keep in mind that the setup that works better depends entirely on the profile and how it was designed.  Some Epson-supplied profiles only work (properly) inside the driver: those are better with "Let printer/driver manage color" and "Host ICM".  For more recent Epson models, I've found the Epson-supplied profiles work fine with the printer profile in QU and "no color adjustment".

Mike

Thanks again

Printed that lot out.

It is a more complicated subject than I thought.

Jeff