Why is the new iMac 5K instead of 4K? It’s all about the video, baby

My gamut measurement of the Retina iMac’s screen. Unfortunately, the 1931 CIE diagram produced by our measuring software is “non-uniform and obsolete.”

I originally wanted to devote at least one story to a qualitative analysis of the Retina iMac’s screen, including a list of physical measurements (gamut, gamma, intensity, and anything else I could measure). However, although I measured like a crazy fiend, my hopes of a constructive analysis were dashed when my expert—Dr. Ray Soneira of DisplayMate—told me that the data gathered was mostly unusable. Primarily, it’s due to my choice of instruments. Sadly, our Spyder4 Elite just wasn’t quite up to the task.

“Your Spyder measurements indicate that the Color Gamut is close but not accurate enough for video production. The most likely reason is that the Spyder is inaccurate because Apple most likely did a better job of accurately calibrating the monitor. The 1931 CIE Diagram that you use is highly non-uniform and obsolete,” Soneira said.

However, he gamely took a look through the results anyway, and the e-mail conversation turned to resolution. Soneira quickly put forward a handy explanation for why Apple chose the “5K” resolution of 5120×2880 rather than one of the myriad of “standard” 4K resolutions. There are of course a lot of technical reasons to pick 5120×2880—at double the older 27-inch iMac’s resolution of 2560×1440, it makes for precisely four times as many pixels and easy scaling—but Soneira’s explanation was particularly insightful.

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