How do I tell whether my MBA M1 is outputting YCbCr or RGB to an external display?

[Aggedor]

I use an M1 MBA connected to a Corsair Xeneon 32UHD144 (32" 4K 144Hz display) via Apple's Thunderbolt 4 cable (so MBA to the display's USB-C input). I use Sonoma 14.1.1 and am getting the full 144Hz under macOS.

The picture (and text) looks great, but how do I tell whether I'm getting the full 10bit RGB 4:4:4? This display does not report color input anywhere in the OSD.

 

[StoneJack]

If it looks great dont bother. Just use and forget. Most displays do not support true 10 bit colors

 

[What's a computer?]

Here's a test pattern for common, low-bandwidth implementations of YCbCr:

https://i.rtings.com/images/test-materials/2017/chroma-444.png

Display at 1 pixel per monitor physical pixel. YCbCr degrades the bottom two lines of text on the test pattern.
Basically, the idea is to use an old-school bitmapped font where the vertical strokes are one pixel wide and perfectly aligned with the monitor pixels. The letters are either saturated red on a saturated blue background, or saturated blue on a saturated red background. On RGB, the writing hurts the eyes and gives flashbacks to the Commodore 64, but is legible, while on low-bandwidth YCbCr, the letters are badly blurred.
The idea behind YCbCr and similar schemes is that each pixel has its own brightness (luminance), but to slash the amount of data to be transmitted, neighboring pixels share colour (chroma) information. This matches how the human eye works: resolution for brightness is far greater than resulation for colour, and the three-channel colour information is compressed into two channels.
For a more sensitive test for YCbCr, you can make your own test pattern. 1-pixel vertical strokes in one colour on a background with different colour but same luminance. Photoshop or GIMP may help you with this, or you can consult the Wikipedia page on YCbCr:

YCbCr - Wikipedia

en.wikipedia.org

 

[Aggedor]

Here's a test pattern for common, low-bandwidth implementations of YCbCr:

https://i.rtings.com/images/test-materials/2017/chroma-444.png

Display at 1 pixel per monitor physical pixel. YCbCr degrades the bottom two lines of text on the test pattern.
Basically, the idea is to use an old-school bitmapped font where the vertical strokes are one pixel wide and perfectly aligned with the monitor pixels. The letters are either saturated red on a saturated blue background, or saturated blue on a saturated red background. On RGB, the writing hurts the eyes and gives flashbacks to the Commodore 64, but is legible, while on low-bandwidth YCbCr, the letters are badly blurred.
The idea behind YCbCr and similar schemes is that each pixel has its own brightness (luminance), but to slash the amount of data to be transmitted, neighboring pixels share colour (chroma) information. This matches how the human eye works: resolution for brightness is far greater than resulation for colour, and the three-channel colour information is compressed into two channels.
For a more sensitive test for YCbCr, you can make your own test pattern. 1-pixel vertical strokes in one colour on a background with different colour but same luminance. Photoshop or GIMP may help you with this, or you can consult the Wikipedia page on YCbCr:

YCbCr - Wikipedia

en.wikipedia.org

Thanks! That test pattern is useful - hurts the eyes but perfectly legible here!

 

[vanc]

If it looks great dont bother. Just use and forget. Most displays do not support true 10 bit colors

That's true. Based on the spec, this monitor uses "8-bit + FRC" to simulate 10-bit. True 10-bit monitors are usually more expensive, such as Apple Pro Display XDR, Dell UP2720Q, etc.