Hi Darius,
Let's start at the beginning and with some questions.
Is you monitor calibrated with some form of colorimeter device? This is the starting pint for colour management.
I should say that the monitor profile has no direct effect on the print but does affect the way the image appears on the screen and therefore affects how you see any image adjustments.

What paper are you using and what are the profiles have you got?
Do they match a) the printer, b) the ink set you are using, c) the paper you are using?
I see from the HP web site they do not seem to supply profiles for this printer, maybe because it is not specifically a "photo" printer.
Independent paper suppliers usually supply profiles for a whole range of printers with their paper, check their web sites if appropriate.

If all this is good, have you set the driver correctly such there are no colour adjustments made by the driver. There is often documentation supplied with a printer profile which tells you how to set the driver.
Is Qimage set up with the monitor profile and printer profile? All this should be visible in the Job properties, bottom right of the main screen.

Prints darker that screen is usually caused by the monitor being too bright. A calibration device with good supplied software will allow you to set brightness to a set value. If not then it's necessary adjust the brightness to match a print and then calibrate.
It's not what is "optimum" but what is correct and matches what I said in a, b & c above and setting the driver correctly.

If you cannot get a profile for your printer/paper combination, you can use "Let driver Manage Colour" in Qimage. You still must set the paper type correctly in the driver.
The Help says;

Terry

Unfortunately that doe not produce a monitor icc profile. Colour management is all about using icc profiles.
None of those are printer profiles    
All driver settings should be done from Qimage using the 3rd icon in from the top right.
When using "let driver manage colour", do as the Help says for driver settings, as quoted in my 1st post, or look directly in the Help.
Terry

Hello Darius,

I use an HP 8600 OfficeJet printer too, and although I never had any hopes (or intentions) of using it to print photos, after a few experiments I'm very pleased and slightly surprised that I am getting fair-quality colour prints from it!  The absolute control over the printer that I'm enjoying with Qimage, and the confidence it gives me to run comparative test-prints is bliss - pure bliss!

I can confirm this!  (As also mentioned by Terry) It's a fact that HP don't supply any ICC profiles for this printer, which I think is very very odd, even though it's marketed primarily as an office-machine.

So even though I've got a fully colour-managed workflow - with a calibrated monitor especially - the only "color-management" option we've got for this printer is to trust it to render our prints with its built-in sRGB "profile", and to prepare our photos accordingly.  In other words, to trim our colours in our image editor to suit an sRGB printer gamut.

This is giving me very respectable prints, with colours and tones that do match those on my monitor, but with some understandable variations based on (a) the well-known fact that the reflective print surface will never have quite the same 'fidelity' that we see on our radiating monitors, and (b) the annoying fact that the names on the packaging on HP's free-sample papers don't exactly match the names provided in the 8600's print-preferences drop-down list of paper types! and (c) when using a third-party/non-HP paper type with this printer then of course we'll get variable results, because the HP driver doesn't "know" how best to manage its impressively high-definition ink-flow onto that alien paper. Hence the need for some test prints.

On that last point, when I'm doing comparative tests I keep careful notes about the "most successful" prints so that I know which "HP printer paper" was theoretically set in my 8600 driver, coupled with which paper-type was physically loaded in my printer-tray.  I record the 8600-driver-named paper type in a meaningfully-named Qimage "Printer Setup", knowing I can reliably return to exactly that driver setting.

As an example, when I load my paper tray with Kodak Premium Photo Paper (250gsm, Gloss)(currently available at good discounts!) I get optimal colour rendition when I "tell" the 8600 driver that it will be printing onto either of "HP Premium Plus Photo Paper", or "HP Advanced Photo Paper".  But conversely, onto that same paper, if I "told" the 8600 that it would be printing onto "HP Bright White Paper" then I'd get wishy-washy pale colours in comparison. (Of course some good or silly permutations can be guessed-at in advance  )

I agree. Setting Qimage to "Let printer/driver manage color" in the "Prtr ICC" option on the Qimage Job Properties tab is working well for me.

I concur.

In fact - on the setting for "best quality output" - although I might be wrong to give credit for this to Qimage, I do thank Qimage and it's marvellous interaction with my printer for the fact that whenever I set my preferred paper type using that Printer/page setup button (the "3rd icon in from the top right" mentioned earlier by Terry), then my printer driver / 8600 preferences are automatically set to "Output Quality" = "Best".  I haven't had to set this myself so far.

I still hope to buy a "proper" colour printer some day!  But in the meantime, for my "not for serious sale" photo prints, I'm rather pleased with this "sRGB only" 8600 OfficeJet printer!

Colin P.

Thanks Fred for that nudge about the HP paper.

Your experience-based recommendation on paper-types is worth a thousand test-prints    so - coupled with my new-found confidence in my 8600 as a moderately capable colour printer - I've added a box of HP Advanced Glossy paper to my shopping list for this weekend.

I'd been wondering if was worthwhile to get a calibration profile for this printer, given that it's only got 3 colour-inks plus black, but perhaps it would be worthwhile after all.  I haven't bought Profile Prism (yet), but I have already used an IT8-target-based profiling scheme (from Wolfe Faust) to calibrate my scanners (I've got an Epson 3170 as well as the scanner in the 8600) ... so I've already done some of the preliminary stuff.  Another 'plus' point (although it's a bitter-sweet one) is that the 8600 printer insists on using only HP-branded inks, so I should at least have consistency in the 'inks' department.

So yes ... a printer profile would nicely close that "colour management loop", and I'd be happily liberated from the "default sRGB presumption" that's locked into the 8600!  I'll review the Profile Prism pages ...

@To Darius, acknowledging your original query:
Sorry if I've slightly hijacked your post with that detour onto paper-types, but hopefully my thinking-aloud to Fred on printer profiles will add some insights to help answer your query.  I'm sure that the absence of specific printer profiles from HP for the OfficeJet 8600 is an exception in the printer market, and (to recap ...) we then have no choice but (a) to presume an sRGB colour space for our "final printer profile", even when we want to print onto different papers, or (b) to take the rather more exotic route of generating our own printer profile(s) (one profile for every permutation of paper-type + ink-brand!), using additional tools like Profile Prism, plus some extra hardware like a scanner.

The HP OfficeJet 8600 is a Curate's Egg of a printer for sure!!!

Colin P.

Ah! Drat! Yes ... that's a rather critical point that I missed!!!  I was being carried away with my optimism earlier!!

In my 8600's "Customize Your Printer" dialogue, if I click the tantalizing tab called "Color Management"  it simply brings up Windows 7's Color Management dialogue, which of course isn't what I/we want?  Sighhhhh ...!

A lovely idea    (though she'd need to do that somewhat indirectly ... not to drift off topic ...  )

Thanks Fred for your sage reality check on my 8600's colour limitations.
Colin P.