MP All Models Only 24bit Color Depth After macOS High Sierra, Mojave?!

MapleGreen

macrumors member
Original poster
Jun 25, 2019
76
5
Hi there!
I noticed after updating from macOS "sierra" by installing "macOS High Sierra" or "Mojave" on my Mac Pro 5.1 with Metal GPU RX580, system report in Graphics/Display section shows 24-bit color instead of 32-bit.
I've also done quite a lot searching about this situation.
some say 8bit difference is about alpha channel and nothing to worry about because in modern systems GPU is handling the rest.
but I observe a lot of difference in color quality, richness and dynamics in color spectrum so I think maybe we can share some information here at least screenshots from different os version (Graphics/Display section) after 10.13 until 10.14.5

How to resolve this bug? if it is a bug. if it's not, why 24bit?

I have to add this, Graphic processing in 32bit seems to be so demanding so I had to disable Retina by alt+Select the low resolution under system performance/Display/Scale to be able to do 4k editing in FCPX.
but in 2160p(low resolution mode) and increasing sharpness in my LG monitor everything is so sharp and beautiful. we know this is not possible in mac book pro or iMac.

so if apple did this for better performance why we don't have such a problem with 32bit color in windows 10 with the same GPU/CPU ?!
Is this a sacrifice for retina processing?

hardware:
Mac Pro 5.1
2 x 3.46 GHz 6 Core Intel Xeon
AMD Radeon RX580 8gb

this screenshot is from sierra 10.12.6
Untitled.png
 

bsbeamer

macrumors 68020
Sep 19, 2012
2,402
1,116
Machine I'm on right now is Mojave 10.14.5 and reports:

Chipset Model: Radeon RX 580
Framebuffer Depth: 30-Bit Color (ARGB2101010)

May want to first check your GPU in Mojave to confirm it is reporting as an RX580 model. You're posting screenshots from older OS versions and not Mojave.
 
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Kubat

macrumors member
Jan 10, 2006
34
8
Poland
I had 24 Bit color - upgraded to latest Boot ROM Version: 144.0.0.0.0
and I have 30bit
 

MapleGreen

macrumors member
Original poster
Jun 25, 2019
76
5
I had 24 Bit color - upgraded to latest Boot ROM Version: 144.0.0.0.0
and I have 30bit
Thanks for the feedback, so what about the last 2 bit, is there any reason for this number?
I have not heard 30 bit before
 

h9826790

macrumors G5
Apr 3, 2014
12,800
5,622
Hong Kong
AGAIK, still AGRB8888, nothing changed.

24bit / 32bit is just a different name for the same thing. You can also call it 8bit colour if you want to, still the same thing.

Anyway, never heard that 32bit colour is too stressful for the GPU, and will make it unable to perform in FCPX if using HiDPI (Retina) options.

My RX580 rendering the screen at 7680x2160 (3840x1080 HiDPI) @144Hz with 30bit colour.
3840x1080 HiDPI.png

And it can still edit 4k in FCPX without any trouble.

For your info, 30bit colour is actually more demanding than 32bit colour. As per your research, there is only 8bit per channel in 32bit, but for 30bit colour, it's 10bit per channel.
 

MapleGreen

macrumors member
Original poster
Jun 25, 2019
76
5
Machine I'm on right now is Mojave 10.14.5 and reports:

Chipset Model: Radeon RX 580
Framebuffer Depth: 30-Bit Color (ARGB2101010)

May want to first check your GPU in Mojave to confirm it is reporting as an RX580 model. You're posting screenshots from older OS versions and not Mojave.
Thanks, it appears as rx580 in mojave, I think it's something to do with boot rom version as kubat said!
[doublepost=1561577755][/doublepost]
AGAIK, still AGRB8888, nothing changed.

24bit / 32bit is just a different name for the same thing. You can also call it 8bit colour if you want to, still the same thing.

Anyway, never heard that 32bit colour is too stressful for the GPU, and will make it unable to perform in FCPX if using HiDPI (Retina) options.

My RX580 rendering the screen at 7680x2160 (3840x1080 HiDPI) @144Hz with 30bit colour.
View attachment 845163
And it can still edit 4k in FCPX without any trouble.

For your info, 30bit colour is actually more demanding than 32bit colour. As per your research, there is only 8bit per channel in 32bit, but for 30bit colour, it's 10bit per channel.
As I mentioned I see a lot of difference in quality between 32bit and 24bit
I know in theory we should not see any difference
Could you please tell me what is your boot Rom version and os version?
 

h9826790

macrumors G5
Apr 3, 2014
12,800
5,622
Hong Kong
Thanks, it appears as rx580 in mojave, I think it's something to do with boot rom version as kubat said!
[doublepost=1561577755][/doublepost]

As I mentioned I see a lot of difference in quality between 32bit and 24bit
I know in theory we should not see any difference
Could you please tell me what is your boot Rom version and os version?
Screenshot 2019-06-27 at 1.48.37 PM.png


If the colour looks wrong, may be you should calibrate it.
Screenshot 2019-06-27 at 1.51.49 PM.png