rec.709 vs rec.709 gamma 2.4 vs rec.709 gamma 2.2

[Joseph Owens]

2.2 is the old standard which referenced phosphor CRT displays.

2.4 is the new standard which is now in widespread use.

jPo, CSI

“I always pass on free advice — its never of any use to me” Oscar Wilde.

[Marc Wielage]

And then there’s BT1886, which is a little bit of both. This is more complex question than you might think.

The thought behind BT1886 is pretty sound. I know of post houses around LA who are aligning the mid-tones and whites to 2.4, but the low-end to 2.2. Spectracal covers it pretty well:

https://www.spectracal.com/Documents/White%20Papers/BT.1886.pdf