30-bit Color on 24-bit Hardware

Hi.

I just wanted to get the word out there for any who may be interested
about this display fidelity extension stuff I've been working on. It's
basically about getting 24-bit hardware to perceptually display 30-bit
color.

General information is available at <http://www.silvasdigital.com/xdf>.

The "meat and potatoes" info is available in the Project Summary and
Findings Report at . . .
<http://www.silvasdigital.com/xdf/XDF Project Summary and Findings Report.pdf>

All the info is free--I don't think there's anything proprietary in
there (though I'm not any kind of legal council)--but since I *have*
spent quite a lot of time on this and I do have bills to pay, I'm only
providing the tech demo (a hi-fi image viewer for Windows) in return
for donations.

Thanks and I hope you find the info to have been worth checking out,
- Ron

"Ron W. Silvas" <contact@silvasdigital.com> wrote in message news:c516aeb9.0409232125.2ab3ed4d@posting.google.com...
> Hi.
>
> I just wanted to get the word out there for any who may be interested
> about this display fidelity extension stuff I've been working on. It's
> basically about getting 24-bit hardware to perceptually display 30-bit
> color.
>
> General information is available at <http://www.silvasdigital.com/xdf>.
>
> The "meat and potatoes" info is available in the Project Summary and
> Findings Report at . . .
> <http://www.silvasdigital.com/xdf/XDF Project Summary and Findings Report.pdf>
>
> All the info is free--I don't think there's anything proprietary in
> there (though I'm not any kind of legal council)--but since I *have*
> spent quite a lot of time on this and I do have bills to pay, I'm only
> providing the tech demo (a hi-fi image viewer for Windows) in return
> for donations.
>
> Thanks and I hope you find the info to have been worth checking out,

Ron, have you written an API for extended-bit printer
drivers? Windows is limited to 24-bit output, and without
the aforementioned API your technology is of very limited
use (at least under Windows).

Rick

"Ron W. Silvas" <contact@silvasdigital.com> wrote in message
news:c516aeb9.0409232125.2ab3ed4d@posting.google.com...
> Hi.
>
> I just wanted to get the word out there for any who may be interested
> about this display fidelity extension stuff I've been working on. It's
> basically about getting 24-bit hardware to perceptually display 30-bit
> color.
>

Perceptually, would anybody see a difference?

On Fri, 24 Sep 2004 11:44:20 +0100, "Des Perado" <des@per.ado> wrote:

>
>"Ron W. Silvas" <contact@silvasdigital.com> wrote in message
>news:c516aeb9.0409232125.2ab3ed4d@posting.google.com...
>> Hi.
>>
>> I just wanted to get the word out there for any who may be interested
>> about this display fidelity extension stuff I've been working on. It's
>> basically about getting 24-bit hardware to perceptually display 30-bit
>> color.
>>
>
>Perceptually, would anybody see a difference?
>

I know my eyes usually tune out at about 150,000 colors ;-)


---Atreju---

Atreju <someone@who.hates.junkmail> writes:

> On Fri, 24 Sep 2004 11:44:20 +0100, "Des Perado" <des@per.ado> wrote:
>
> >
> >"Ron W. Silvas" <contact@silvasdigital.com> wrote in message
> >news:c516aeb9.0409232125.2ab3ed4d@posting.google.com...
> >> Hi.
> >>
> >> I just wanted to get the word out there for any who may be interested
> >> about this display fidelity extension stuff I've been working on. It's
> >> basically about getting 24-bit hardware to perceptually display 30-bit
> >> color.
> >>
> >
> >Perceptually, would anybody see a difference?
>
> I know my eyes usually tune out at about 150,000 colors ;-)

It's not that simple. The colors from a normal display aren't
distributed evenly in the human color space, and there's a difference
between the contrast you can see between two adjacent colors and the
total number of colors in an image. So it's quite possible, depending
on the conditions, for 24 bits to be inadequate. I would expect this
more for LCD's than for CRT's, though, both because of their dynamic
range and because the nonlinearity of a CRT actually helps. I think
many LCD's use temporal dithering already, as they tend to be a bit
short of full 24-bit capability.

--
-Stephen H. Westin
Any information or opinions in this message are mine: they do not
represent the position of Cornell University or any of its sponsors.

"Rick" <me@privacy.net> wrote in message news:<2ri1d1F1b8f8pU1@uni-berlin.de>...
> Ron, have you written an API for extended-bit printer
> drivers? Windows is limited to 24-bit output, and without
> the aforementioned API your technology is of very limited
> use (at least under Windows).

Hi, Rick.

No, I haven't written any sort of print driver.

And, like you, I suspect that visualizing in color depths beyond what
your target output device is capable of producing might not be the best
idea, but . . .

Paper is by no means the only target medium out there these days,
right? The video game and multimedia industry produces content for
display on computer monitors and televisions, the motion picture
industry--including their animation and special effects studios--
produce content for film and 30-bit digital projection, and I believe
medical imaging usually requires greater than 24-bit color fidelity (or
greater than 8-bit grayscale, etc.).

And even if 30-bit color didn't have any practical uses–-which is not
the case–-we'd only know that by first researching it, right? I'm just
making some of that research available to those who are similarly
interested.

Thank you for asking about this,
- Ron

"Des Perado" <des@per.ado> wrote in message news:<2ric4nF19vv8dU1@uni-berlin.de>...
> Perceptually, would anybody see a difference?

If your question is . . .
"Would anybody see a difference between the true 30-bit color (of, say,
a Matrox Parhelia) and the synthesized 30-bit color (which I'm talking
about)?"

The short answer is: No, I don't think they would–Not if the 30-bit
synthesizing is implemented correctly.

But if your question is . . .
"Would anybody see a difference between 24-bit color and 30-bit color?"

As Mononen pointed out, the short answer is: Yes they would, but only
in some images. (Thanks, Mononen. =)


More detailed answers to these questions can found in . . .
<http://www.silvasdigital.com/xdf/XDF Project Summary and Findings Report.pdf>
.. . . with the latter question dealt with in the
"24-bit Color vs. 30-bit Color" section.

Thank you for the discussion,
- Ron

westin*nospam@graphics.cornell.edu (Stephen H. Westin) wrote in message news:<s0656321or.fsf@diesel.graphics.cornell.edu>...
> It's not that simple. The colors from a normal display aren't
> distributed evenly in the human color space...So it's quite possible,
> depending on the conditions, for 24 bits to be inadequate. I would
> expect this more for LCD's than for CRT's, though, both because of
> their dynamic range...I think many LCD's use temporal dithering
> already, as they tend to be a bit short of full 24-bit capability.

Hi, Mr. Westin.

Thank you for pointing that out--about the difference between human
vision and the color space of RGB displays. I tried to deal with that
a little in the pre-mentioned PDF's "Beyond 24-bit Color" section,
where I mention that "24-bit color allows for hue and saturation level
precision beyond human visual sensitivity but fails to naturally allow
for the specification and display of the many hundreds of
intensity/brightness levels per color that humans can visually
distinguish."

I've found that 24-bit artifacts are quite demonstratable on both CRTs
and LCDs, alike, (as can be experienced with the previously mentioned
tech demo) but I believe that, if anything, they would be more
noticeable on CRTs because the higher dynamic range of a CRT means that
an 8-bit color channel's 256 intensity/brightness levels have that much
more perceptual space to cover, right?

I believe you are correct about LCDs already using temporal dithering--
often to extend native 18-bit LCD hardware (6 bits per RGB channel) to
24-bit color. But I believe there *are* true 24-bit LCDs also, and what
I find interesting is that, apparently, some companies are starting to
use temporal dithering in *them* to extend them to 30-bit color--BUT,
unless there's some kind of good hardware reason to do this (which I
wouldn't know about), my research seems to indicate that they should
instead be using traditional *spatial* dithering for this extension
because . . . If properly implemented, spatial dithering can be used to
extend 24-bit color to 30-bit color with *none of its traditional
dithering noise visible* because of the perceptual closeness of 24-bit
color space neighbors (More about that in the PDF).

Thanks again for pointing out the color space deal, and thank you for
the discussion,
- Ron

"Ron W. Silvas" <contact@silvasdigital.com> wrote in message
news:c516aeb9.0409241202.6a4f5b6c@posting.google.com...
> I've found that 24-bit artifacts are quite demonstratable on both CRTs
> and LCDs, alike, (as can be experienced with the previously mentioned
> tech demo) but I believe that, if anything, they would be more
> noticeable on CRTs because the higher dynamic range of a CRT means that
> an 8-bit color channel's 256 intensity/brightness levels have that much
> more perceptual space to cover, right?

I've been following this thread with interest, but a couple of
comments seem appropriate at this point.

First - what "higher dynamic range" of the CRT? Neither the
color gamut or the contrast of the typical CRT display is
much different that what can be obtained with the LCD.
What I think the problem here really is, is a difference in the
response curves of the two technologies. CRTs have a very
nice (perceptually) "gamma" sort of response, whereas LCDs
have a perceptually-nastier "S-shaped" response that cannot
adequately be compensated for with only 8 bits per channel,
not if you still intend to have 8 bit/channel of perceptually linear
intensity control. The solution here is greater dynamic range
(bit depth) at the panel (i.e., at the driver level), to permit
compensation for the panel's response and thus present a
"CRT-like" 8-bit input. Fortunately, we ARE starting to see
10-bit LCD drivers entering the market.

Bob M.

"Bob Myers" <nospamplease@address.invalid> wrote in message news:Kw15d.11687$MS.7082@news.cpqcorp.net...
>
> "Ron W. Silvas" <contact@silvasdigital.com> wrote in message
> news:c516aeb9.0409241202.6a4f5b6c@posting.google.com...
> > I've found that 24-bit artifacts are quite demonstratable on both CRTs
> > and LCDs, alike, (as can be experienced with the previously mentioned
> > tech demo) but I believe that, if anything, they would be more
> > noticeable on CRTs because the higher dynamic range of a CRT means that
> > an 8-bit color channel's 256 intensity/brightness levels have that much
> > more perceptual space to cover, right?
>
> I've been following this thread with interest, but a couple of
> comments seem appropriate at this point.
>
> First - what "higher dynamic range" of the CRT? Neither the
> color gamut or the contrast of the typical CRT display is
> much different that what can be obtained with the LCD.

Nonsense. The backlight technology used in LCDs (at least
those in the con/prosumer range) precludes the possibility that
they can match the gamut of a decent CRT. E.g. a $700
Mitsubishi 2070 easily outgamuts a $1300 Apple Cinema
Display.

> What I think the problem here really is, is a difference in the
> response curves of the two technologies. CRTs have a very
> nice (perceptually) "gamma" sort of response, whereas LCDs
> have a perceptually-nastier "S-shaped" response that cannot
> adequately be compensated for with only 8 bits per channel,
> not if you still intend to have 8 bit/channel of perceptually linear
> intensity control. The solution here is greater dynamic range
> (bit depth) at the panel (i.e., at the driver level), to permit
> compensation for the panel's response and thus present a
> "CRT-like" 8-bit input. Fortunately, we ARE starting to see
> 10-bit LCD drivers entering the market.

More nonsense. No amount of compensation will overcome
the limitations of LCD's backlight technology. One has the
choice of losing near blacks altogether, or settling for a
constant and muddy bluish or grayish glow instead of black.

Rick