CMYK monitors? ;)

Has anyone ever tried to make a good CMYK monitor? Such a monitor could have a gamut which matches print very closely, at the expense of overall gamut. It would be dedicated to preparing images for print. Maybe this kind of monitor would be cheaper to make than a wide gamut RGB monitor?

CMYK and RGB are entirely different ways of creating color. http://www.pixelphoto.com/htdocs/html/rgb_cmyk.html

http://www.madmousergraphics.com
web design, print design, photography

"LauraK" wrote in message

CMYK and RGB are entirely different ways of creating color. http://www.pixelphoto.com/htdocs/html/rgb_cmyk.html

I realise that. What I want is a monitor which can display near the full gamut of my inkjet printer.
The images would still be RGB, just that the CMYK monitor would be able to display the colours which
can be printed, but which cannot be displayed by a standard monitor. This device would probably have far
less blue/red gamut than a standard monitor, but that would be the tradeoff – it’s merely for print work.

A standard monitor would still be required for optimising images for transmissive devices. (such as for web publishing,
projecting, etc). In fact, the CMYK monitor would probably be treated more like "electronic paper" – it would be too inconvenient to use for day to day use.

Greg.

"Greg" wrote in message

"LauraK" wrote in message

CMYK and RGB are entirely different ways of creating color. http://www.pixelphoto.com/htdocs/html/rgb_cmyk.html

I realise that. What I want is a monitor which can display near the full gamut of my inkjet printer.
The images would still be RGB, just that the CMYK monitor would be able to display the colours which
can be printed, but which cannot be displayed by a standard monitor. This device would probably have far
less blue/red gamut than a standard monitor, but that would be the tradeoff – it’s merely for print work.

A standard monitor would still be required for optimising images for transmissive devices. (such as for web publishing,
projecting, etc). In fact, the CMYK monitor would probably be treated more like "electronic paper" – it would be too inconvenient to use for day to day use.

Which inkjet do you own that you believe has a larger gamut than your monitor? I use a calibrated and profiled LaCie, together with both the Epson 2200 and 1280 – and I see colors on my monitor that have NEVER come out of my printers, but not vice-versa. Once I apply a profiled soft-proof though, what I see is what I get.

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"Flycaster" wrote in message

Which inkjet do you own that you believe has a larger gamut than your monitor? I use a calibrated and profiled LaCie, together with both the Epson 2200 and 1280 – and I see colors on my monitor that have NEVER come out of my printers, but not vice-versa. Once I apply a profiled

soft-proof

though, what I see is what I get.

Most if not all inkjet printers do. It’s been published in many places and is very common knowledge.
It’s mainly cyans for which inkjet printers more gamut.

I’ve been through this with someone else. I eventually resorted to printing out two colour patches, side by side,
with my inkjet printer. These two patches look VERY different on print. I created them scientifically, such that
when a colour management engine brings them into the gamut of the person’s monitor, that I was having
the discussion with, they looked identical on their screen. When I did this, they then believed me, for the most
part, but even then, they suggested that PERHAPS my colorimeter was measuring reflections from the media.
This is despite the fact that I can use the colorimeter to measure essentially the same hue on a glossy IT8
target, and the reading matches the IT8 data for that target. 😉

Would you like me to do this for your monitor? You’d need to send me the ICC profile that you’d be using to
view the two patches.

Greg.

Greg wrote:

What I want is a monitor which can display near the full gamut of my inkjet printer.

A monitors gamut is typically larger than an inkjet, as far as I know. CMYK colors like pure cyan towards green (and yellow too sometimes), can’t be simulated in a RGB monitors gamut, but overall, the gamut of a good monitor is often larger than the gamut of an inkjet printer.

This is the gamut of my CRT monitor compared to the profile describing my Epson printers gamut (on Epson glossy paper): <http://home18.inet.tele.dk/madsen/monitor/fw900_2100.jpg> (The monitor is the transparent one).

Rotated here:
< http://home18.inet.tele.dk/madsen/monitor/fw900_2100_cyan_gr een.jpg> Here it’s easy to see, that my monitors gamut can’t cover some of the most saturated cyans and greens of the printers gamut. Adobe RGB(1998) covers it better than my monitor does, but Adobe RGB(1998) can’t cover it completely either.
if I should cover them _almost_ completely, it would require a much larger RGB gamut, like WideGamutRGB for instance and you can’t produce monitors with a gamut like that (yet).

I wonder if OLED displays will have a larger gamut than the gamut of CRT monitors and TFT panels of today, but it will take a couple of years or maybe much more, before we see large OLED displays in the stores, I guess. Any thoughts on that anyone?

Happy new year.

—
Regards
Madsen.

"Thomas Madsen" wrote in message

Greg wrote:

Here it’s easy to see, that my monitors gamut can’t cover some of the most saturated cyans and greens of the printers gamut. Adobe RGB(1998) covers it better than my monitor does, but Adobe RGB(1998) can’t cover it completely either.
if I should cover them _almost_ completely, it would require a much larger RGB gamut, like WideGamutRGB for instance and you can’t produce monitors with a gamut like that (yet).

This is *exactly* what I meant. Yes, I *know* that overall, a monitor has a larger
gamut. 🙂

I’d like a CMYK "monitor" which *can* display that extra cyan gamut, at the *expense*
of the other gamut which a monitor can display, but a printer cannot. However, I only
want this device if it can be made cheap enough. I just thought that perhaps it would be
easier to make a device like this using CMYK reflective technology, than wide gamut RGB
phosphors.

That extra green/cyan gamut is *entirely* useful and visible to me – I have taken photos on slide
film which only my 1270 printer can do justice too – the print looks the same as the slides, but
the lovely deep cyans just get turned to blue on my monitor, and it’s not the fault of the monitor –
the colours are simply outside it’s gamut.

Greg.

I wrote:

That extra green/cyan gamut is *entirely* useful and visible to me – I

have

taken photos on slide
film which only my 1270 printer can do justice too – the print looks the same as the slides, but
the lovely deep cyans just get turned to blue on my monitor, and it’s not the fault of the monitor –
the colours are simply outside it’s gamut.

What I meant is that it’s not due to monitor calibration/profiling.

Greg.

Greg wrote:

I just thought that perhaps it would be easier to make a device like this using CMYK reflective technology, than wide gamut RGB phosphors.

How would you accomplish that? It requires a monitor who doesn’t emit its own light, but instead reflects (or hold back) light from another source, like ink on paper does. Maybe an aluminium foiled deflector beanie wrapped around the head, and a light source over the monitor, reflecting onto the surface of the monitor via the deflector beanie, but how do you get the picture up on the screen too and how do you get the light deflected from the beanie spread evenly over the entire surface of the monitor? (just kiddin’ 🙂

—
Regards
Madsen.

Greg wrote:

What I meant is that it’s not due to monitor calibration/profiling.

True. It’s not due to poor calibration and profiling. It’s the monitor that can’t simulate the pure cyan and yellow inks with RGB colors, as far as I know.

—
Regards
Madsen.

"Thomas Madsen" wrote in message

How would you accomplish that? It requires a monitor who doesn’t emit its own light, but instead reflects (or hold back) light from another source, like ink on paper does. Maybe an aluminium foiled deflector beanie wrapped around the head, and a light source over the monitor, reflecting onto the surface of the monitor via the deflector beanie, but how do you get the picture up on the screen too and how do you get the light deflected from the beanie spread evenly over the entire surface of the monitor? (just kiddin’ 🙂

Why is the beanie required? The light source would not necessarily have to come directly from one’s head, would it? 🙂
An angled light source would be fine, assuming the display technology allowed for the angle, of course.

Anyway, it looks like the idea isn’t far away!
http://www.nature.com/nsu/030922/030922-10.html

(I was aware of some work with monochrome electronic paper, but not colour!!)

Greg.

On 30-Dec-2003, "Greg" wrote:

"LauraK" wrote in message

CMYK and RGB are entirely different ways of creating color. http://www.pixelphoto.com/htdocs/html/rgb_cmyk.html

I realise that. What I want is a monitor which can display near the full gamut of my inkjet printer.
The images would still be RGB, just that the CMYK monitor would be able to display the colours which
can be printed, but which cannot be displayed by a standard monitor. This device would probably have far
less blue/red gamut than a standard monitor, but that would be the tradeoff – it’s merely for print work.

A standard monitor would still be required for optimising images for transmissive devices. (such as for web publishing,
projecting, etc). In fact, the CMYK monitor would probably be treated more like "electronic paper" – it would be too inconvenient to use for day to day use.

It’s probably possible to build something like a CcMYy monitor (you can’t have K with any monitor technology I know of) or maybe a RMGCYB. It could even be useful for proofing in some cases. You will, of course, need profiles for each printer since printer gamut varies from printer to printer. The big problem I see is the transmissive vs. reflective one (light vs pigment if you prefer.) Even with in gamut images, I find the monitor to be a really poor proof of the printed color saturation. I think the current reality is for truly accurate proofing a paper proof is required.

—
Tom Thackrey
www.creative-light.com
tom (at) creative (dash) light (dot) com
do NOT send email to (it’s reserved for spammers)

Has anyone ever tried to make a good CMYK monitor? Such a monitor could have
a gamut which matches print very closely, at the expense of overall gamut.

My friend Cary spent a good deal of time as a programmer for Disney’s animation studios. He said they use monitors which have a custom set of phosphors, and a much wider gamut than ordinary monitors (and, apparently, an astronomical price tag to match).

In theory, it would be possible to design a monitor which didn’t use three phosphors at all, but actually used a set of phosphors which could create the colors attainable in CMYK but not RGB (a cyan and a yellow phosphor would do it). Such a monitor would require a video card which created an RGBCY signal, and would (presumably) require driver software capable of separating RGB color values into RGBCY color values, or (better yet) software that was written to work in a color space such as L*a*b and produce RGBCY color values for display on the monitor.

Doable? In theory, yes. The manufacturing and other technical costs involved in producing such a monitor, and the programming challenge involved in making applications take advantage of such a monitor, would be nontrivial.

—
Rude T-shirts for a rude age: http://www.villaintees.com Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

Which inkjet do you own that you believe has a larger gamut than your monitor? I use a calibrated and profiled LaCie, together with both the Epson 2200 and 1280 – and I see colors on my monitor that have NEVER come out of my printers, but not vice-versa.

A CMYK device can produce colors outside the RGB gamut; the RGB gamut does not completely enclose the CMYK gamut, even though the CMYK gamut is smaller. Pure yellow can’t be reproduced in RGB; there are also deep fire-engine reds outside the RGB gamut they look too magenta in RGB), and cyans and teals which are outside the RGB gamut.

Inkjet printers start with RGB input, and separate to their own particular CMYK, so it’s difficult to get pure primaries (for example, to print a solid yellow with no trace of other colors) on a consumer inkjet printer. You can do it in a CMYK device like a proofer or a printing press, however.

When I was working prepress, before I moved into design and image retouching, I had a job I used to do for a catalog of commercial uniforms and apparel every year. It was very important to the client that the printed catalog matched the actual fabric samples exactly (or as exactly as was technically possible). They used one particular shade of teal in many of their fabric swatches that was in the CMYK gamut but not in the RGB gamut, meaning it never looked right on the screen no matter what–and I was using *very* expensive Barco monitors with hardware color calibration, under controlled coditions. So it was a proof-adjust-proof situation, almost as bad as working on the file blind. It’s frustrating when you encounter this kind of limitation.

—
Rude T-shirts for a rude age: http://www.villaintees.com Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

On Wed, 31 Dec 2003 17:25:19 +1100, "Greg" wrote:

Why is the beanie required? The light source would not necessarily have to come directly from one’s head, would it? 🙂

Greg, he’s kidding.

And by the way, you need to really look into some books on color theory, particularly the difference between transmissive color and relfective color to see why your asking for a CMYK monitor is a tough nut to crack from an engineering and physics perspective.

And while you’re at it, thinking about the same printed color when viewed under different light conditions (flourescent, incandescent, and daylight). Trust me on this, your eye actually does not receive the same color in all three lighting conditions.

That’s sort of why there are color profiles for devices and different printing conditions. That’s also why Pantone continues to make swatch books for inks. And that’s why it takes experience to understand how what you see on the screen will translate into the printed page.

— JC

"Tacit" wrote in message

Which inkjet do you own that you believe has a larger gamut than your monitor? I use a calibrated and profiled LaCie, together with both the Epson 2200 and 1280 – and I see colors on my monitor that have NEVER come out of my printers, but not vice-versa.

A CMYK device can produce colors outside the RGB gamut; the RGB gamut does

not

completely enclose the CMYK gamut, even though the CMYK gamut is smaller.

Pure

yellow can’t be reproduced in RGB; there are also deep fire-engine reds

outside

the RGB gamut they look too magenta in RGB), and cyans and teals which are outside the RGB gamut.

Very small incursions into the super saturated cyan gamuts are about all that I have (personally) noticed. Frankly, my monitor makes saturated reds that CMYK can’t even come close to making. Soft-proofing reveals significant gamut clipping in reds that I can *see* on the monitor, but can’t print to either CMYK or one of my inkjets.

I dunno…it could be the way *I* see color that is at play here…

Inkjet printers start with RGB input, and separate to their own particular CMYK, so it’s difficult to get pure primaries (for example, to print a

solid

yellow with no trace of other colors) on a consumer inkjet printer.

Neither my 2200 nor my 1280 has any trouble whatsoever with pure yellows – true "gold", otoh, is a different issue. Gold is easy for the CMYK work I do, but for some reason these printers just have a hard time making it.

You can do
it in a CMYK device like a proofer or a printing press, however.
When I was working prepress, before I moved into design and image

retouching, I

had a job I used to do for a catalog of commercial uniforms and apparel

every

year. It was very important to the client that the printed catalog matched

the

actual fabric samples exactly (or as exactly as was technically possible).

They

used one particular shade of teal in many of their fabric swatches that

was in

the CMYK gamut but not in the RGB gamut, meaning it never looked right on

the

screen no matter what–and I was using *very* expensive Barco monitors

with

hardware color calibration, under controlled coditions. So it was a proof-adjust-proof situation, almost as bad as working on the file blind.

It’s

frustrating when you encounter this kind of limitation.

Gotcha.

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"J C" wrote in message

On Wed, 31 Dec 2003 17:25:19 +1100, "Greg" wrote:

Why is the beanie required? The light source would not necessarily have

to

come directly from one’s head, would it? 🙂

Greg, he’s kidding.

For heavens sake – I know he’s kidding about the beanie. 🙂 However, I do not think he was kidding about thinking that the light needed to
shine directly onto the screen, from a point near the eyes – I thought that was the
point he was trying to make. (but in a humorous way) If he was kidding about that
too, then I apologise – I didn’t realise that.

And while you’re at it, thinking about the same printed color when viewed under different light conditions (flourescent, incandescent, and daylight). Trust me on this, your eye actually does not receive the same color in all three lighting conditions.

I don’t understand what the problem with that is. So we need a controlled light source.
We need that already, when viewing prints.

That’s sort of why there are color profiles for devices and different printing conditions. That’s also why Pantone continues to make swatch books for inks. And that’s why it takes experience to understand how what you see on the screen will translate into the printed page.

I think it’s *lousy* not being able to see all the colours properly on screen before I print them. ;^)
And other folks probably do too – otherwise NEC/Mitsubishi would not have developed their new
extended gamut monitor.

Greg.

Tacit wrote:
[re cmyk monitor]

In theory, it would be possible to design a monitor which didn’t use three phosphors at all, but actually used a set of phosphors which could create the colors attainable in CMYK but not RGB (a cyan and a yellow phosphor would do it).

A reflected light CRT that simulated the lighting effects of paper would be a technologically different solution, but a CRT with CMY phosphors would not accomplish anything.

If you look at it a different way, an RGB monitor *is* a CMYK monitor because cyan controls the amount of red light emitted, magenta controls green, and yellow controls blue.

What’s different is the "background" color – meaning the color when no signal is present – of RGB is black, and for CMYK it is white.

—

Mike Russell
www.curvemeister.com
www.geigy.2y.net

"Tacit" wrote in message

Inkjet printers start with RGB input, and separate to their own particular CMYK, so it’s difficult to get pure primaries (for example, to print a

solid

yellow with no trace of other colors) on a consumer inkjet printer. You

can do

it in a CMYK device like a proofer or a printing press, however.

This is something I’ve been wondering about. Perhaps good inkjet printers, when the driver
is in the raw, non colour adjusted mode, try to ensure that for RGB codes of (255,255,0),(255,0,255) and
(0,255,255), the printer will lay down only it’s primary yellow, magenta, and cyan inks, respectively, which
at least allows the limit of the printer’s gamut to be reached in raw mode? It would then come down
to how accurately/well the profiler makes use of that gamut, though. Is this plausible?

Greg.

Greg wrote:

For heavens sake – I know he’s kidding about the beanie. 🙂 However, I do not think he was kidding about thinking that the light needed to shine directly onto the screen, from a point near the eyes – I thought that was the point he was trying to make.

Yes, that was the point I was trying to make. 🙂
I was just joking about the deflector beanie.

I think it’s *lousy* not being able to see all the colours properly on screen before I print them. ;^)
And other folks probably do too – otherwise NEC/Mitsubishi would not have developed their new
extended gamut monitor.

As far as I know, the Nec/Mitsubishi monitors, is very close to Adobe RGB(1998) in gamut. That isn’t enough. Adobe RGB(1998) can’t cover the pure cyans and yellows from a CMYK device either.

—
Regards
Madsen.

"Thomas Madsen" wrote in message

As far as I know, the Nec/Mitsubishi monitors, is very close to Adobe RGB(1998) in gamut. That isn’t enough. Adobe RGB(1998) can’t cover the pure cyans and yellows from a CMYK device either.

Yes, that’s my understanding too. And I agree/understand that it’s still not enough, but it’s a good step in the right
direction. 🙂

Just looking at some nice dark saturated greens on my profile test chart from my Epson 2200. Guess what –
even these greens are out of a monitor’s gamut – in fact I have to go toWide Gamut RGB before they’re in gamut – not even Ekta Space
is good enough. And once again, the difference is noticable – looking at the colour on screen is quite disappointing, side by side with the print.

Greg.

A reflected light CRT that simulated the lighting effects of paper would be a technologically different solution, but a CRT with CMY phosphors would not accomplish anything.

It wouldn’t accomplish anything if you tried to use CMY phosphors to represent CMYK color modelling. What it *would* do is help increase the gamut of the monitor, if the colors were used correctly.

For example, a monitor that had RGB phosphors and cyan and yellow phosphors could represent yellow using the yellow phosphors rather than red and green phosphors, which would get you closer to CMYK yeloow. However, you couldn’t represent green by using the cyan and yellow phosphors–you’d still use the green phosphors instead.

If you look at it a different way, an RGB monitor *is* a CMYK monitor because cyan controls the amount of red light emitted, magenta controls green, and yellow controls blue.

Well, yes, except that in the real world, full-spectrum light does not contain only red, green, and blue-frequency photons–it also contains yellow, and purple, and violet, and so on.

Using three primary colors can simulate a wide range of color, but it can’t reproduce all the visible color, because the three color receptors in the eye don’t respond *only* to photons of the corresponding frequency; they actually respond to all frequencies of light, though they are maximally sensitive to specific frequencies.

—
Rude T-shirts for a rude age: http://www.villaintees.com Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

Perhaps good inkjet printers,
when the driver
is in the raw, non colour adjusted mode, try to ensure that for RGB codes of (255,255,0),(255,0,255) and
(0,255,255), the printer will lay down only it’s primary yellow, magenta, and cyan inks, respectively, which
at least allows the limit of the printer’s gamut to be reached in raw mode? It would then come down
to how accurately/well the profiler makes use of that gamut, though. Is this plausible?

It’s possible, sure, if the drivers and profiles are carefully crafted. I know my own Epson consumer-grade printer doesn’t work this way; a pure RGB yellow produces a printout that has a slight, teeny trace of red ink in it (though you have to look with a magnifying glass to see it).

—
Rude T-shirts for a rude age: http://www.villaintees.com Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

Just looking at some nice dark saturated greens on my profile test chart from my Epson 2200. Guess what –
even these greens are out of a monitor’s gamut – in fact I have to go toWide Gamut RGB before they’re in gamut – not even Ekta Space
is good enough.

Yep. And teal is even tougher still. In fact, teal can be hella difficult to reproduce in *any* color model.

—
Rude T-shirts for a rude age: http://www.villaintees.com Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

"Tacit" wrote in message

Yep. And teal is even tougher still. In fact, teal can be hella difficult

to

reproduce in *any* color model.

This was the first link that Google returned for a search on "teal" and "color":
http://www.nsvrc.org/saam/tealchart.html
Bit of a weird web page to have the colour codes for teal. 🙂 🙂

Seriously, that looks similar to the first patch my eyes were drawn to on my reflective IT8 test chart, as being
reproduced badly on my monitor. When I first got into profiling, I threw up my hands in despair, because that
colour would NEVER be reproduced properly, and I decided that ICC profilers were just a heap of junk.
I once manually tried to create the colour on screen, by twiddling the RGB values in the colour picker in Photoshop.
This was, of course, fruitless. 🙂

Greg.

I’m sorry if that link I posted in my previous message is offensive to anyone – I didn’t think before posting it.
I’m truly sorry.

Greg.

"Greg" wrote in message
news:3ff24896$> >Would you like me to do this for
your monitor? You’d need to send me the ICC

profile that you’d be using to
view the two patches.

Sure, why not. Give me an e-mail address.

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"Flycaster" wrote in message

Sure, why not. Give me an e-mail address.

Sigh – you were supposed to say "no, it’s ok – I believe you". 😉

I’ll be using patch H8 of my Wolf Faust reflective IT8 target. This patch has a Lab value of 41.23 -33.09 -35.86.;
I’ll print this patch, and the colour that Photoshop 7.01’s colour management engine would produce on *your* display,
side by side with my Epson 2200. I’ll then measure the two patches (because there’s no guarantee that my printer and profile
will produce the intended colours exactly), and send you an image that has the two measured colours. These two colours
should look nearly identical on your screen. You can then either trust my eyes that the two patches on print look very
different, or you can trust the measured dE between the two measurements, or you can ask me to send you the actual
print so you can verify the measurements yourself, and get it measured any way you like.

We’re *already* in private correspondence re: printer pre-linearization. ;^)

Greg.

Mike wrote:

A reflected light CRT that simulated the lighting effects of paper would
be a technologically different solution, but a CRT with CMY phosphors would not accomplish anything.

Tacit wrote:

It wouldn’t accomplish anything if you tried to use CMY phosphors to represent CMYK color modeling. What it *would* do is help increase the gamut of the monitor, if the colors were used correctly.
For example, a monitor that had RGB phosphors and cyan and yellow phosphors could represent yellow using the yellow phosphors rather than red and green phosphors, which would get you closer to CMYK yellow.

It would seem reasonable that adding Cyan and Yellow phosphors to RGB can only help, and indeed I agree the gamut would be increased, in theory. If this is all you’re saying, fine.

But there is a fatal flaw to the suggestion that this would be useful for CMYK proofing. There is also a list of practical flaws if you simply want a better additive CRT color system.

The crucial point is that the cyan channel, being an additive color, cannot be used to add cyan to a white page – only a black one. What use, then, is it for the purposes of CMYK?. Short answer: none.

When I said above that a CMY system would be of no interest for CMYK proofing, and that cyan is really red in disguise, I was referring to exactly this essential difference between an additive color space and a subtractive one.

The same goes, BTW, for the yellow phosphor- since it cannot be used to represent yellow on a white page, it’s of no interest for CMYK.

Tacit wrote:

However, you couldn’t represent green by using the cyan and yellow phosphors–you’d still use the green phosphors instead.

Digressing a moment to discuss your 5 color additive color space, you are touching here on another practical problem here involved in even using the extra channels in an additive space. The fact that there are now multiple representations possible for the same color will create a lot of complexity in driver and colorimeter logic. And there are a host of other problems with more hardware, loss of brightness for example, because you cannot light up all the phosphors at once.

For the foreseeable future, we can get much more leverage with purer phosphors.

Mike said:

If you look at it a different way, an RGB monitor *is* a CMYK monitor because cyan controls the amount of red light emitted, magenta controls green, and yellow controls blue.

Tacit wrote:

Well, yes, except that in the real world, full-spectrum light does not contain only red, green, and blue-frequency photons–it also contains yellow, and purple, and violet, and so on.

Minor correction. There are no purple or violet photons. This is because pure spectral light, by definition, contains no purple, violet, or magenta. These colors are the result of mixtures of red and blue spectral light.

Using three primary colors can simulate a wide range of color, but it can’t reproduce all the visible color, because the three color receptors in the eye don’t respond *only* to photons of the corresponding frequency; they actually respond to all frequencies of light, though they are maximally sensitive to specific frequencies.

Other primary color sets are certainly possible, though there are good physiological reasons for our choice of RGB.

I do stick to my original point that a CMY additive color system is irrelevant to the subtractive color space that must be used for CMYK proofing.

I would even contest your claim that the RGB-CY space would have a wider gamut.

A five color additive system, such as you mention, has a theoretical gamut advantage, but aside from the hardware complexity, the logic to drive it is enormously more complex, we won’t be seeing this in the near future because most of the advantages of a 5 color space would be met simply by purer RGB phosphors.
—

Mike Russell
www.curvemeister.com
www.geigy.2y.net

"Mike Russell" wrote in message

A five color additive system, such as you mention, has a theoretical gamut advantage, but aside from the hardware complexity, the logic to drive it

is

enormously more complex, we won’t be seeing this in the near future

because

most of the advantages of a 5 color space would be met simply by purer RGB phosphors.

It probably goes without saying that my proposal is for a reflective (subtractive) device. However, on the subject
of adding phosphors to additive displays, isn’t it true that some television tubes already have an extra yellow phosphor?

Also, Sony now have a new RGBE (E = emerald) CCD sensor for digital cameras……….

Greg.

"Greg" wrote in message

"Flycaster" wrote in message

Sure, why not. Give me an e-mail address.

Sigh – you were supposed to say "no, it’s ok – I believe you". 😉
I’ll be using patch H8 of my Wolf Faust reflective IT8 target. This patch has a Lab value of 41.23 -33.09 -35.86.;
I’ll print this patch, and the colour that Photoshop 7.01’s colour management engine would produce on *your* display,
side by side with my Epson 2200. I’ll then measure the two patches

(because

there’s no guarantee that my printer and profile
will produce the intended colours exactly), and send you an image that has the two measured colours. These two colours
should look nearly identical on your screen. You can then either trust my eyes that the two patches on print look very
different, or you can trust the measured dE between the two measurements,

or

you can ask me to send you the actual
print so you can verify the measurements yourself, and get it measured any way you like.

We’re *already* in private correspondence re: printer pre-linearization.

Ah, there are lots of Greg’s around and I wasn’t sure it was you.

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Greg wrote:

"Mike Russell" wrote in message

A five color additive system, such as you mention, has a theoretical gamut advantage, but aside from the hardware complexity, the logic to drive it is enormously more complex, we won’t be seeing this in the near future because most of the advantages of a 5 color space would be met simply by purer RGB phosphors.

It probably goes without saying that my proposal is for a reflective (subtractive) device. However, on the subject
of adding phosphors to additive displays, isn’t it true that some television tubes already have an extra yellow phosphor?

Do you have a link for this? If it has four guns, then I have to recant my original point about the practicality of adding more guns. I did a quick search and found yellow CRT phosphors, but this was in connection with old radar displays.

Also, Sony now have a new RGBE (E = emerald) CCD sensor for digital cameras……….

Extra filters may well improve the color response of an image sensor, but in this situation, unlikd that of a CRT, there is no added cost in terms of mechanical complexity, or overall sensitivity.
—

Mike Russell
www.curvemeister.com
www.geigy.2y.net

"Mike Russell" wrote in message

However, on the subject
of adding phosphors to additive displays, isn’t it true that some television tubes already have an extra yellow phosphor?

Do you have a link for this?

Not yet. 🙂 I *thought* I heard some ads for a particular make of television, a *long* time ago, make a feature of
an extra yellow phosphor, for extra vividness, or something. I’ve just examined mine, though, and it certainly doesn’t
have a yellow phosphor.

I did find this link about adding a yellow to EL displays to make them brighter:
http://www.findarticles.com/cf_dls/m3161/12_47/54946340/p1/a rticle.jhtml

Greg.