Just for information.....

I have a 2-year old Intel iMac with OS X 10.4 (Tiger), and I was sure I had seen the gamma figure of 1.8 somewhere in my setup, long before I had any idea what it meant. So I just ran through the OS X 'Display Calibrator Assistant' again, now that I know a bit more about what it's doing.

It indicated that my iMac display does indeed have a NATIVE gamma response of around 2.2. In fact, my results showed just over 2.3, but of course it's quite a subjective process. It might well be 2.2 after a few refills of my Friday evening wineglass.

But my default iMac display profile specifies a TARGET gamma of 1.8. This probably means that most Mac users are still in fact using an output gamma of 1.8, unless (like me) they re-calibrated their displays and are now using a custom calibration profile with gamma 2.2.

In the 'Simple' mode of the OS X Display Calibrator Assistant there are just two options for target gamma (see screenshot). That's pretty clear. The 'Expert' mode, however, has a slider going from 1.0 to through the ceiling, and by way of guidance says "In most cases it's best to use the Mac Standard gamma of 1.8". Not very helpful.

On a Mac with the default Target gamma of 1.8, both sRGB and GC(2.2) images will appear over-corrected in comparison to what the artist intended. (Put simply, if not entirely accurately, too bright).

And images made by the artist using the same Mac will appear under-corrected when viewed on an sRGB PC display. (.. ditto ditto... too dark).

So I think the simple message to Mac OS X users in this community should be... run the OS X Display Calibrator Assistant in Simple mode, and set your Target gamma to 2.2.

ducks and runs for cover

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)