Wow, thanks very much for your detailed explanation! I didn't expect there
are so many factors may influence it haha, I will recalibrate and see if
there is any difference when I change the GPU, and thanks again for your
help!
On Fri, Aug 28, 2020 at 11:25 AM Graeme Gill <graeme@xxxxxxxxxxxxx> wrote:
tong chen wrote:
Hi developer, currently I have a 10bit display, but my gpu only supportsto
8bit. If I switch to a gpu that supports 10bit in the future, do I need
recalibrate the display? Or is there a difference between the calibration
done under 8bit and 10bit?
Hi,
in theory there may be a difference due to the bit depth, but in
practice it's unlikely to be noticeable. The fact is that the repeatability
of your display and any instrument is not of the same order as 8 bit or
10 bit, so the quantization difference is literally lost in the noise.
(And this is assuming that you are using an actual 10 bit capable display
and are connecting it with a 10 bit capable interface.)
Any practical sort of calibration or profiling isn't running though
all bit codes - it would take far too long - so there's typically nothing
lost in sampling codes that are common between 8 bit and 10 bit.
(And presumably you are using the dispread -Z parameter to properly
use just 8 bit quantized test values).
The only exception would be if your display is particularly non-linear
at some point in its gamut, and where the extra 2 bits might really have
some influence. But the calibration system is going to have trouble
anyway, so the result isn't likely to be that nice, leading to
the conclusion that if you are after robust image quality, use a display
that is reasonably linear thru-out its gamut.
An additional practical aspect is that a number of the current
desktop API's (i.e. MSWindows) are pretty much locked into 8 bits, so the
application writers have to go to heroic efforts to access 10 bits, using
3D graphics API's etc. The last time I checked the whole area was poorly
standardized.
[ And don't confuse frame buffer bit depth with per channel LUT output
bit depth. Lots of systems have 10 bit precision in their final
calibrated
output via this mechanism, even if their frame buffers are stuck at 8
bits. ]
Of course it is good practice to re-calibrate and re-profile when changing
major operating modes of your display pipeline, just in case something
about the change alters the rendering behavior in a way that affects the
color.
Cheers,
Graeme Gill.