The first series of Sony OLED pro monitors looked green to me, and until recently I didn’t know why. It turned out I wasn’t hallucinating, and I now know a little more about what I didn’t know I didn’t know.

Read the full article: The Judd Offset: What I Didn’t Know I Didn’t Know About OLED Monitors at DV Info Net (http://www.dvinfo.net/uncategorized/the-judd-offset-what-i-didnt-know-i-didnt-know-about-oled-monitors.html)

Lost me almost immediately when it got into the color science, but that's my failure. I'm not much of an "under the hood" guy.

This did give me pause: "One or two rental houses have Flanders Scientific (FSI) monitors, whose color is relatively good but aren’t considered robust enough for field use." I've carted my FSI 2641 all over the place for three years and it's going strong. Has been back for calibration a couple of times but it was only marginally out of spec. Many of the DIT's I work with consider them workhorses and several own them. I've sniffed at the Sony OLEDs but still consider them a little "dangerous" to use as a reference on set.

The trouble is that we're now in a situation where (for a cinematographer) just what is "correct"?

In the early days, it was (at least in theory!) much easier as all aspects of the chain were defined for colorimetry etc. With a vastly greater array of display technologies, that's far more difficult to precisely define nowadays.

But no display should have anything like a definable colour cast per se. It's easy to define a neutral input signal - in the analogue world it was zero subcarrier for PAL/NTSC, in the component world it's where the colour difference signals are null. So feed such a signal into the monitor, and then the relative r,g,b drives of that should be made so that the (greyscale) image looks neutral - simple as that.

Simple as that for monochrome signals at least. Start adding colour into the image and the various colorimetric factors will define how exactly the rendered colour actually matches the real scene - and any R,G,B system can only ever be an approximation to the real (spectral) scene. Hopefully an approximation that is accurate enough for a human eye to perceive as reasonable.

But that's a different matter to an overall colour cast. Feed a greyscale into a monitor and it should look grey, end of story.