At last - 10-bit color in OS X

Macs have for many, many years supported 24-bit color, this dates way back to the introduction of the Macintosh II. This was a little later enhanced to add an additional 8-bits for 'alpha channel' information which basically allows transparency of layers of images over each other.

Note: 24-bit color means 8-bits for Red, 8-bits for Green and 8-bits for Blue. This means you can have 256 shades of Red, Green and Blue values mixed together to produce 16 million colors. (Actually 256 x 256 x 256 = 16,777,216)

As you might have guessed theses days a mere 256 shades of each primary color is insufficient for the level of detail that many creative people need in for example PhotoShop. As a result for quite a while Windows has supported '10-bit' color aka. 'Deep Color'. This gives you 10-bits for Red, 10-bits for Green, and 10-bits for Blue for a total of 30-bits compared to 24-bits and hence can support 1024 x 1024 x 1024 or 1,073,741,824 which as you can see is vastly more potential shades/colors.

Adobe have previously said their Mac version of PhotoShop potentially is ready to support 10-bit color and is merely waiting on Apple to add support for this. Bizarrely it is possible already on a Mac to use 10-bit color including in PhotoShop but only by running Windows via Boot Camp so it is not a hardware issue. As a result many users have been asking Apple for some time to remedy this omission.

This old 2013 article may be of useful background - http://www.dpreview.com/forums/thread/3538545

Well it recently emerged that without any fanfare Apple have finally added support for 10-bit color in El Capitan 10.11.1. (It was not in the first El Capitan release.)

Note: It appears that in order to provide the additional bits for color information Apple have reduced the number of bits available for alpha-channel information down to 2 so the total number of bits per pixel is still a total of 32 - i.e. 10 + 10 + 10 + 2.

See this article for more details http://petapixel.com/2015/10/30/os-x-el-capitan-quietly-unlocked-10-bit-color-in -imacs-and-mac-pros/

Sadly as usual Apple do not provide much information on this sort of enhancement. So while it is clear this works on the new iMacs it is not yet clear whether this will work on other models like the Mac Pro. Remember as detailed above it has already been previously proven that existing Mac hardware including the old classic Mac Pro can do 10-bit color in Windows via Boot Camp so it is not a hardware issue.

Has anyone been able to get 10-bit color working on a Mac Pro?

(For the benefit of our spelling challenged cousins in the colonies I have used the 'American' spelling of color. 🙂)