Christoph Koulen writes:
:: >
:: > You do realize that potentially no monitor, and certainly no LCD screen,
:: > can output this level of color, right? (Perhaps they dither it down?)
:: > 10 bits per channel is primarily useful for internal calculations, as
:: > far as I know.
:: >
:: > So you'd better start your investigation with: "can I even see 10 bits
:: > per channel?" rather than "how?".
:: >
:: > -ray skoog
:: >
::
:: To my knowledge, a monitor is an analogous device, that can potetially
:: display _any number_ of intermediate shades of each primary colour.
I take it you mean "analogue" when you write "analogous"?
If so, then you need to consider the existence of _digital_ flat panel (FP)
displays, most of which are, today, LCD devices of some sort.
Though one could argue that (ultimately) these, too, are analogue at bottom,
it is not usually useful to think in these terms unless you are a device
physicist or a LCD driver circuit designer.
:: Isn't the RAMDAC (Digital-Analog Converter) the chip, that converts a
:: digital value (i.e. a 10bit color value) into a voltage that ultimatly
:: drives the intensity of each of the monitor's color guns? I cannot see a
:: reason, why a color gun wouldn't respond to any intermediate voltage
:: level. If it weren't driven by a RAMDAC of inherently limited resolution
:: but a power supply capable of outputting a continuous voltage range...
If the FP is digital then you must send spatially discrete amplitude-quantised
signals to it (usually via a DVI-I or DVI-D interface) to drive the thing.
:: The delimiting factor, I agree, would be the human eye! I wonder, if it
:: is capable of distinguishing between 1024 shades of a primary color?
::
:: Christoph Koulen
The eye _can_ see the grey level transitions in a corrected (both
gamma and device S-curve) 8-bit grey ramp if (i) the display is wide
enough or (ii) you zoom in on a just a portion of the ramp. These do
disappear when you have "1024 shades of a primary colour". But I'm
talking LCD panel here.
On a CRT it's possible to see the transitions though it is much harder
and you need a high-end (== expensive) CRT.
The reasons are several. W/o getting into details, the beam spot tends to
smear the transition edges and the CRT is inherently spatially noisy.
With a digital LCD panel, there _is_ no "spot", and there is an _exact_
spatial correspondence between what is in the framebuffer and what is
on the monitor.
By the bye, the latter fact is also the reason why the "sub-triad
addressing" (a.k.a subpixel subsampling) used in M$ Cleartype doesn't
"work" on a CRT or an analogue LCD panel.
Dean S. Messing
Center for Displayed Appearance
Information Systems Technologies Laboratory
Sharp Laboratories of America
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