attention color whizes: non-typical sRGB/RGB/ProPhoto question

[tho_mas]

it turned out that a strip from that area to white was also problematic.
As far as cyans are concerned, if you can ball park them in my plot below you might see what is happening:

I can't … as I simply don't understand your graph. So I don't know what to look at.
I am just a simple "user" of colour managed applications...

When did I say cyans?

You didn't talk about cyans… but I have looked at the cyans.

When you compare the gamuts AdobeRGB (white) and ProPhoto (wireframe) abscol in relation to D50…:

… you will see that blue->white / cyan->white / magenta->white is potentially problematic.
You can see it even better when you spin the graph:



So… I've just looked at all the "blues" (incl. cyan).

Now, you didn't adress my question.
If there are saturated blues in AdobeRGB that are not contained in ProPhoto … why do all the blues and cyans of ProPhoto clip when I "softproof" relcol to AdobeRGB and enable gamut warning?

[joofa]

I can't … as I simply don't understand your graph. So I don't know what to look at.

It shows you the same gamut in a linear space that are you used to seeing in a nonlinear space such as Lab.

I am just a simple "user" of colour managed applications...
You didn't talk about cyans… but I have looked at the cyans.

When you compare the gamuts AdobeRGB (white) and ProPhoto (wireframe) abscol in relation to D50…:

… you will see that blue->white / cyan->white / magenta->white is potentially problematic.
You can see it even better when you spin the graph:

So… I've just looked at all the "blues" (incl. cyan).

Now, you didn't adress my question.
If there are saturated blues in AdobeRGB that are not contained in ProPhoto … why do all the blues and cyans of ProPhoto clip when I "softproof" relcol to AdobeRGB and enable gamut warning?

First of all, I did not make those programs you used so I don't know what they are doing internally.

Secondly, I thought it would appear from my graph, and then, I did a quick calculation and it would appear that a saturated cyan Prophoto RGB (D50) is outside the gamut   of Adobe RGB (D65). I don't see what is the big surprise here? I have to check my calculation though.

Joofa

[tho_mas]

I don't see what is the big surprise here?

no surprise... for me. It's in agreement with what most people say: all AdobeRGB colours are encompassed by ProPhoto.

[joofa]

no surprise... for me. It's in agreement with what most people say: all AdobeRGB colours are encompassed by ProPhoto.

No.

[digitaldog]

no surprise... for me. It's in agreement with what most people say: all AdobeRGB colours are encompassed by ProPhoto.

They are when you plot them correctly as you’ve done. As all such graphers do. Begging the question again (for the last time), why joofa appears to refuse to look at these 3D gamut plots using either the tool in the CS utility or using Bruce’s plots on his very web site.

[tho_mas]

No.

so why then can I create high saturated ProPhoto blues that clip in AdobeRGB?

[jeremypayne]

No.

What's "a color"?  Seriously.

Seems like we several definitions going ...

[joofa]

What's "a color"?  Seriously.

Seems like we several definitions going ...

Why is it so difficult to realize that both Adobe RGB (D65) and Prophoto RGB (D50) have colors that are outside each other's gamut? This was the premise of the whole exercise since a 2D representation of gamut as chromacity diagrams does not show that. Didn't I start from there?

Doesn't my plot show that clearly?

Joofa

[joofa]

so why then can I create high saturated ProPhoto blues that clip in AdobeRGB?

Highly saturated blues of Adobe RGB (D65) and Prophoto RGB (D50) are not within each other's gamut. Simple as that.

Joofa

[tho_mas]

Highly saturated blues of Adobe RGB (D65) and Prophoto RGB (D50) are not within each other's gamut. Simple as that.

so when the highest saturated blues of AdobeRGB are "outside" of ProPhoto... why do all ProPhoto blues clip in (i.e. are "outside" of) AdobeRGB?

[Eric Myrvaagnes]

What's "a color"?  Seriously.

Seems like we several definitions going ...

As in Through the Looking Glass (Lewis Carroll):

> The name of the song is called "HADDOCKS' EYES."'
> 'Oh, that's the name of the song, is it?' Alice said, trying to
> feel interested.
> 'No, you don't understand,' the Knight said, looking a little vexed.
> 'That's what the name is called. The name really is "THE AGED AGED
> MAN."'
> 'Then I ought to have said "That's what the song is called"?' Alice
> corrected herself.
> 'No, you oughtn't: that's quite another thing!
> The song is called "WAYS AND MEANS": but that's only what it's
> called, you know!'
> 'Well, what is the song, then?' said Alice, who was by this time
> completely bewildered.
> 'I was coming to that,' the Knight said.
> 'The song really is "A-SITTING ON A GATE": and the tune's my own
> invention.'

Or,

"when I use a word, it means precisely what I want it to mean, nothing more nothing less." (Humpty-Dumpty)

 

[joofa]

so when the highest saturated blues of AdobeRGB are "outside" of ProPhoto... why do all ProPhoto blues clip in (i.e. are "outside" of) AdobeRGB?

Study my diagram very carefully that I am presenting for the nth time below. Do you see that angle between Adobe RGB (D65) and Prophoto RGB (D50)? These two gamuts are not aligned!



Sincerely,

Joofa

[tho_mas]

Study my diagram very carefully that I am presenting for the nth time below. Do you see that angle between Adobe RGB (D65) and Prophoto RGB (D50)? These two gamuts are not aligned!

my reply:

I did not make those programs you used so I don't know what they are doing internally

[joofa]

my reply:

I did not make those programs you used so I don't know what they are doing internally

Thomas, I mentioned that before also, and I do it again. I have not used a single commercial program for making my plots. All the data is available online on the Internet such as Wikipedia. I, myself, started from there. Anybody can produce the plots that I have done using basic plotting tools.

I will be honored if that is the case that my simple plots are showing something that you didn't see in pricey commercial programs!

Joofa

[tho_mas]

Thomas, I mentioned that before also, and I do it again. I have not used a single commercial program for making my plots. All the data is available online on the Internet such as Wikipedia. I, myself started from there. Anybody can produce the plots that I have done using basic plotting tools.

still begs the question why ALL ProPhoto blues clip in AdobeRGB (converting relcol as well as abscol).

[joofa]

still begs the question why ALL ProPhoto blues clip in AdobeRGB (converting relcol as well as abscol).

Angle, between the gamuts. Please see my diagram again. Well, to be honest, angle alone is not enough. There is another reason also but that is beyond the scope of this discussion. Don't worry about that in the particular case of Adobe RGB (D65) and Prophoto (D50) saturated colors.

Joofa

[tho_mas]

Angle, between the gamuts. Please see my diagram again.

Again: I don't understand it. It's the first time that I've seen color spaces plotted this way.
You could as well tell me it's the outline of a new fish cracker that will be sold outside of Chicago but inside of New York.

Does it show the same as these two?
http://www5.pic-upload.de/07.01.11/gnhzegyold.jpg
http://www5.pic-upload.de/07.01.11/ghj9m2umlcw7.jpg

[joofa]

Again: I don't understand it. It's the first time that I've seen a color spaces plotted this way.
You could as well tell me it's the outline of a new fish cracker that is outside of Chicago but inside of New York.

Trust me it is the real representation of gamuts. With a great advantage of being in linear space. I can't overemphasize that fact.

There is no need to go into nonlinear Lab gamuts, such as those in the commercial programs presented here. In fact, though I could be wrong, and I have to verify my findings, but there is an issue of gamut being twisted in those programs but I was afraid to point that out. Because if I did, Digital Dog will be all over me, saying "how come you are right and these established tools have the possibility of being incorrect?"

Joofa

[joofa]

Does it show the same as these two?
http://www5.pic-upload.de/07.01.11/gnhzegyold.jpg
http://www5.pic-upload.de/07.01.11/ghj9m2umlcw7.jpg

See, my plots are in linear space and not in nonlinear space, such as the Lab plots you are showing. But you can see the equivalent information with full 3D rotation as I do on my computer. Linearity is very helpful!

Joofa

[MarkM]

OK Joofa, lets figure it out. I'll start by paraphrasing what I think you are getting at. Although you keep saying people don't understand your graph, I think most people with any colorimetric education do. So I explain what I think you saying and you can correct me if I'm wrong. OK?

So we take the unit RGB values from each space:
R= [1, 0, 0]
G = [0, 1, 0]
B = [0, 0, 1]

And we convert them to XYZ values via an absolute colorimetric rendering for each color space in question. This essentially creates three axis representing three coordinate systems: the XYZ space is indicated by the main axis of the cube in your projection. The three coordinate systems are related via an affine transformation, so the relationship is linear.

Now the way 3D coordinates are normally plotted on a 2D diagram only gives you one perspective. If you look straight down the Z axis you will see the plot like the first attachment. The blue dots are the AdobeRGB primaries; the red dots are the ProPhoto primaries. I've circled the blue primary. Looking at this graph, it appears that the AdobeRGB primaries are completely contained within the Prophoto RGB primaries.

But here's the twist: since this is a three dimensional plot projected into two dimensions, we don't get the whole picture. The second attachment shows what it looks like if we rotate the space and look straight down the X axis instead. (Pay attention to the labeled axis). Now you can see that the blue primary (circled) actually falls outside of the triangle formed by the ProPhoto apices. In three dimensional space that blue primary actually falls outside the solid formed by the ProPhoto primaries. Which is to say it is out of gamut.

Since a chromaticity diagram only shows two dimensions of a three dimensional space, we often don't get the whole picture. This is especially important when comparing gamuts because you are only seeing one slice of a three dimensional volume.

Does this accurately represent what you are getting at Joofa?