Sunday, October 30, 2016

"Color Accuracy" Needs of a Photographer/Retoucher

Disclaimer: I'm not resurrecting this blog. I just needed a place to put this stuff. I don't have time to write anymore.

I’m going to put this in writing because well, I don’t want to misrepresent myself through a podcast or get side-tracked by some random detail. Here it is: There are so few displays on the market that are built to the requirements that photographers need.

Color Accuracy
This is generally the big keyword. That’s the lure though. When people google “color accurate displays” (as I have in the past), they’ll find monitors that are color accurate. Sometimes this means factory-calibrated(1). Sometimes this means that the display can be calibrated properly. Sometimes this means that they provide hardware calibration for the internal LUT and not just software calibration of your monitor profile. Personally, I have not found this to be the biggest issue with displays created for photography/editing. Specifically because I think most of the manufacturers have gotten their stuff together and created panels that calibrate to proper specifications. In other words most manufacturers sell some displays capable of being calibrated to a delta E < 2 or 3 which is industry standard. What I'm saying is that color accuracy is just the tip of the iceberg.

Brightness and Contrast
Manufacturers love advertising how bright and contrasty their monitors can be. Specifications like 1500:1 contrast ratio or 500cdm2 are probably (I’m guessing here) good for gaming but rather useless for photography/editing especially when calibrate the display to match prints. This is because paper generally doesn’t hold more than 250:1 contrast ratio(2) and often much less. So if you’re looking at a display calibrated to 1500:1 contrast ratio display and then printing on paper at 250:1 contrast ratio, I’m going to bet that you’ll be disappointed in the print. And as far as brightness goes, 120cd/m2 is industry standard though I generally calibrate to 100cd/m2 brightness (and 0.4 black point) because of my working environment. This allows me to create prints like I see on the displays. All that being said, if a display doesn’t calibrate down to 100cd/m2 accurately (without a lot of color fluctuation) or doesn’t allow me to lower the brightness down to 100cd/m2 at all, then it’s not a suitable display for photography/editing needs. And this is where software comes in.

Calibration Software
I’ve played around with Spyder, Colormunki, i1Display Pro, Eizo color software utilities (and more). Often what I have experienced is that the black point is not something that you can set. Sometimes you can’t even set the white point. Without these 2 things, you can’t really control for the contrast ratio. For example with the i1Display software, I’m getting more contrast ratio than I’d like because the software does not allow me to set a black point. This means that I am using the factory black point which unfortunately for me is lower than 0.4. With a white point of 100cd/m2 I’m getting a contrast ratio around 280:1 or so. It’s not a deal breaker but it goes to show that without proper tools, all the hardware in the world is moot. Dell has a good software set that is capable of doing hardware LUT calibration. Unfortunately for me, the Dell color calibration software does not work on Macs. The workaround is to create the profile on a PC and then port it over to your Mac. Who has time for that? But since we’re on the topic of software, let’s talk a little about hardware.

Calibration Hardware
As I mentioned, I’ve used the gamut of calibration devices and the corresponding hardware through the years. Colormunki skewed green. Spyder skewed red. Neither could calibrate the Macbook Pro display properly. The i1Display Pro isn’t perfect but it’s proper. Both the i1Display Pro and the ColorMunki are owned by the same company (X-Rite). But the best piece of hardware that I’ve ever used is the one that I’ve never had to use. It’s the built-in calibration sensor in the Eizo CG276W. It pops up every I don't even know how many hours and calibrates itself and then goes back into its bezel. Sometimes I see it do its thing. Usually I don’t. The point is, I never forget to calibrate and it’s always done right by me. I’ve never had the need to pull out my third party calibration sensor to test or calibrate the Eizo manually. And that’s the way it should be. It should just work.

Color gamut
Admittedly I’m not such a stickler for color gamut. Since I process in and for sRGB, I don’t usually find myself pushing the boundaries of hardware or software color gamut. So to me, a monitor capable of 95% is the same as a monitor capable of 102% AdobeRGB color gamut. Both will accurately represent all the colors of sRGB and I’ll be none the wiser. That said, more is usually better. Many monitors these days are pushing 99% or sometimes more than 100% of the AdobeRGB color space.

Panel uniformity
This is the Achilles Heel of all displays. This is the one specification few manufacturers tells you about (and the one that you’re likely to really notice). Because when you calibrate a display, you take measurements from the center of the display. These measurements are used to generate the color profile for that display. And here’s where most users and manufacturers call it a day. Upon generating said color profile they say their display is "color accurate”. But who says the measurements taken at the center of the display is consistent with the rest of the display? The easiest way to test this is to pull up a white document/picture and make it full screen. You’ll quickly see whether the white in the center is the same as the white in the corners. And therein lies the rub. Sometimes there is a variance in color and brightness from one part of the display to another. 

And that’s exactly what I found with my BenQ SW2700PT ( and also my Dell UP2716D. Even though the Dell comes factory-tested for panel uniformity and even provides you with those test results on paper, I have found that over the last 6 months of usage, this panel is not capable of proper panel uniformity. In fact I’ll be honest, I wrote this whole thing (yes everything above), just to talk about panel uniformity. When I’m looking at a B&W set and on the left side of my display the pictures appear greenish and on the right side of my display they appear reddish, I get really upset. They're supposed to be grey! As in devoid of color! Sure, with a B&W set I can just tell myself, “Don’t sweat the color differences, they're not real”. But what about when I’m trying to cross-process a whole set of color pictures the same way? And I can’t trust what I’m seeing? When comparing images, I have to move pictures from the left to right and vice versa just to make sure what I’m seeing isn’t the result of the monitor but rather the actual processing of the image. No bueno. Bad hombres. Throw in some more Spanish here to show how unhappy I am about panels with poor uniformity. Even with the Eizo CG276W there is a slight color shift between different portions of the panel but that color shift is unremarkable compared to what I see with the Dell and with the BenQ. 

And then there is brightness uniformity. Since the BenQ didn’t come with a panel uniformity report, it failed on both color uniformity and brightness uniformity across the entire display. I know this because I tested panel uniformity with the i1Display Pro. The Dell on the other hand does well with brightness uniformity but not so well with color uniformity (in spite of being factory tested). In fact a quick google search returns this issue as the first search result ( I suspect panel degradation over time which explains how a display might have passed testing at the factory but lose color and brightness uniformity over time.

We spend thousands of dollars on lenses and cameras. Hell, I know some people that go full hog on their camera bags and then skimp on their displays. How strange is that? I spend several days a week looking my monitor (48+ hours). I don’t think it’s too much to ask for a monitor that is not only calibrates properly AND retains its color accuracy and uniformity over time. A $2000 Eizo really isn’t that much considering most camera bodies and several of your lenses (not mine) cost more. That said we don’t all have the budget for the Eizo CG318-4K which is what I’m drooling over at the moment as I’m contemplating selling the Dell UP2716D. Then again I have an Eizo CG276W at the office just collecting dust these days. Decisions decisions.

(1) Which is nice but not necessary if you have your own hardware for monitor profiling. You really should have your own i1Display Pro to create your own profiles. Notice I didn’t say Spyder or ColorMunki both of which I’ve used in the past. Furthermore the i1 software is weak in comparison to the more robust software out there that come straight from the factory like Dell and Eizo.

(2) 100cd/m2 divided by 0.4 black point = 250:1 contrast ratio.

(3) I was not able to achieve that level of uniformity in my own testing with the BenQ SW2700PT. In fact, my own testing led me to return the BenQ SW2700PT.


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