Monitor to Print Matching or... How to avoid "dark prints"
(An expanded version of my Feb. 2009 newsletter article)
Now there certainly can be many other causes, such as OS updates that suddenly render drivers incompatible (they might still work but give you wonky results), updates to programs like Adobe Lightroom where suddenly they utilize a new OS level print-driver interface standard not yet supported by most printer drivers (this happened last year in Lightroom v2) and so on. However, I am going to focus on LCD displays and their calibration.
Before I do that however, I will reiterate the importance of having the correct printer driver installed, once that matches your OS version, as well as ensuring you are not using a UNIX “Gimp Print” driver in Mac OS X. Most printers will be automatically supported by OS X, even without installing or downloading a current driver, but you will not be getting the correct colour rendering since the built-in drivers are often completely different than the manufacturer's ones. Also, if you are using a new exotic paper from Hahnemühle, Harmon or Ilford for example, and have downloaded ICC profiles for it, these profiles are pretty much all designed to be used with the manufacturer's drivers as well and will not give good results with the built-in UNIX drivers.
I strongly suggest that if you have never actually installed a printer driver (yet your printer has been working) that you download and install the correct driver from Epson or Canon's website. Once you do, delete any instances of your printer from the printer list (Printer Utility app for OS X v10.4 and earlier or the Printers & Faxes section in System Preference for OS X v10.5 Leopard) and then manually add the printer back in. However keep in mind that if you had any custom setups for that printer, as far as paper settings and such, they will likely also be deleted, so proceed with caution – at the very least, write down your custom settings so you can get back to them if need be. So... on to LCD display issues...
There seems to be an almost irrational drive for display manufacturers to constantly upgrade the brightness and contrast specifications for their displays and while these improvements look good on paper and might be an advantage if, for example, you are using your monitor to watch movies, these “improvements” are certainly detrimental if you are using your display to work in an imaging program like Photoshop or Lightroom and are adjusting your photos based on what you see on your screen.
A properly calibrated LCD display will look dark and flat with a rather warm colour balance, in fact dramatically so compared to the way most displays are set up from the factory. If you have been using a display in an uncalibrated state, your initial reaction upon performing your first monitor calibration will likely be “Yuk! That looks totally screwed up... what did I do wrong?”
So, if you do not have a monitor calibrator (and your display did not come with one, like some of the higher end NEC and LaCie models), then the first thing to do is go out and buy one! Montior calibration is the first and most important step to ensure you are getting a good match between display and print. Here at Beau Photo, we stock the DataColor (ColorVision) Spyder3 series as well as the Xrite (Gretag-Macbeth) Eye One series. There are subtle differences in these and certain models might be suited better to certain types of display, but I can work through that if you in to buy one from us. This article is not about any calibrator specifically, so on to some recommended settings...
So you have your fancy new Model XYZ LCD display that boasts amazingly high luminance and contrast values and you have just bought a calibrator... so what settings should you use? There seems to be quite a bit of disagreement as to what the “ideal” or “correct” settings should be, so all I can do is relate what has worked for me personally. Please note that I have certainly not tried every monitor out there so yours may be different, but so far what I am about to recommend has worked quite well on the majority of displays I have had experience with.
So here is what I recommend: a white point of 5000K, a gamma of 2.2 and, if at all possible, a luminance value of between 80 and 120 Cd/m^2. Why? Read on...
I'll get the non-controversial setting out of the way first – gamma. You can view gamma as the brightness (or darkness) of the mid-tones in relation to the shadows and highlights. Putting it simply, gamma 2.2 is what most displays work best with. Unless you have very specific needs, you should always calibrate to gamma 2.2. In the old desktop publishing days when one generally worked with images in the ColorMatch RGB space, gamma 1.8 was indeed the standard and Macintosh systems in general, prior to OS X, were also “designed” around a display gamma of 1.8, which appears considerably brighter than a gamma 2.2 display. This has all changed over the years though and now gamma 2.2 is basically the standard and most commonly used working spaces in Photoshop are also gamma 2.2, such as sRGB, AdobeRGB, Wide-Gamut RGB and so on.
Next is white point, how warm (yellowish) or cool (blueish) the monitor appears when displaying neutral tones. It seems that most people recommend using 6500K and this is also a preset in even the least expensive calibrators – in fact with some introductory level models, it is the only preset (which is why I don't recommend those). Despite the fact that most working spaces are designed around 6500K, I personally feel that a monitor calibrated to 6500 looks a little to cool, has a little too much apparent contrast often and has slightly elevated brightness in mid-tones. A display calibrated to 5000K just seems to match prints better to my “eye”. When I profile my monitors, I usually generate two calibrations, one at 5000K and “for fun”, one at 6500K as well. Invariably, I find the 5000K calibration to be a much closer match to colour-managed prints than the 6500K one. I am not going to argue about the technical reasons why “this should not be” since I have had very good results with my method. To me the proof is when I look at a print , look at my display and say “Yup... that's darn close!”, and generally 5000K does that for me. Maybe not with every single combination of monitor, calibrator, printer and paper, but for me, certainly the vast majority. Now things can get a little more complicated as far as luminance and perceptual interactions with ambient lighting, as I'll detail in my next section...
For luminance values, or putting it simply, how bright the monitor appears, I would recommend between 80 and 120 Cd/m^2 – if possible. Many lower end calibration systems do not allow you to manually input this value, but most will display the resulting luminance of your display after calibration. I say “if possible” because in some cases it is simply impossible to dial the monitor down far enough to get into this range. For example, the new 24” Apple iMac, with the glossy screen, has a minimum luminance setting of around 220! That is very nearly three times as bright as what I would personally want to use for image editing! In addition, the instructions with some monitor calibration kits simply ask that you put the monitor's settings (as far as brightness and contrast) to their factory defaults. This again results in images that look far brighter than they will on a print. What I am getting at here, is that even after calibration, it is still very possible for your display to be far brighter than it should, which of course, is pretty much defeating the whole purpose of calibration in the first place!
The above information is, I believe, why many people might be experiencing “prints that are too dark” issues. What can you do about it, apart from trying to find some old CRT which when cranked up to the max, might only have a luminance of 70-90? Well, the easiest thing to do, if your display has the adjustment capability, is do dial it back significantly until it falls into the recommended brightness range. The other, would be for ICC profiling tools to offer a new “Bright LCD Editing” option so that resulting prints match your displays more closely, however that type of option does not yet exist as far as I know.
Ideally, if your display cannot be dialed back enough, you can either replace it with one that can, or in the case of the Apple iMac, you could plug in an external display that yields a better calibration. Alternatively, you can try a program called ColorEyes Display Pro, which does have additional control over adjustments on Apple iMacs and Apple Cinema displays, or at the very least, ColorEyes has the ability to artificially dial back the intensity of the screen by modifying the white point of the video card LUT. There is a danger of introducing image posterization (banding in subtle gradients) if this dialing back is too aggressive, but often it is minimal and at least one then gets a much better overall calibration as far as density and luminance.
Finally, even with a properly profiled display at the correct luminance setting, one can still get prints that look quite far off of what one sees in Photoshop while editing in the default RGB space. One way you can get a better idea of what a print will look like, is to use Photoshop's "Simulate Paper Color" in the View->Proof Setup-> Custom menu, in conjunction with the ICC profile you are using to print with. This will often show you the loss of saturation and contrast a print might have, although I personally see this preview as often being overly pessimistic... in other words, my prints will often actually look better than the preview.
(This article may be further expanded on in the near future...)