sRGB vs Adobe RGB How wrong am I?

[xpatUSA]

OK! I get it. I have ironed my fingers. Ouch!! One more thing? Why not use the entire [visible] color [gamut] as a color space?

Because it is curved and would require a great many primaries to approximate it, not to mention the enormous files resulting from that approach. Assuming that my edits in the quote are what Ed meant.

I suppose that too many out of gamut colors would then be forwarded to the internet or printers...yes?

Only sort of. Your supposition implies that a normal capture will be dripping with out-of-gamut colors. I've already mentioned Pointer's Gamut and provided links. Did you take a look? Most colors collected within that gamut are also inside sRGB.

A useful app is ColorThink where the gamut of any capture can be displayed against several color spaces, 2D or 3D.

[billtils]

Not quite true Bill.....

Which part of what I typed is not true? I ask not in any querulous way but because if I have got somethng wrong I'd like to correct it!

If you meant that there's more to it than what's in my post, yes, I agree.

[Manfred M]

OK! I get it. I have ironed my fingers. Ouch!! One more thing? Why not use the entire RGB color mode as a color space? I suppose that too many out of gamut colors would then be forwarded to the internet or printers...yes?

Out of gamut is not an issue until one tries to display or print those colours; rendering intents ensure that they can be printed / displayed, but the accuracy of the colours will be off.

I'm not sure as to the technical reasons that we use the current colour spaces, but from a purely practical point of view, I am not aware of any current devices that can reproduce even the full ProPhoto RGB colour space, much less the whole gamut of human vision. Given when the colour spaces that we use were introduced, one can assume that the practicalities of computing power and the limitations of the technology that they were being implemented for drove some of the decisions. The CIE L*a*b* (1976) does exactly what you are suggesting, but very few photographers work in the L*a*b* colour space because, other than the L* channel, it is not very intuitive to use.

The top end computer screens can do Adobe RGB and some high end ink jet photo printers, given the appropriate base to print on do exceed Adobe RGB in places..

The internet and printers don't particularly care about the colour space that is used. There are really two issues; the first is unless the software is colour managed, the default colour space is assumed to be sRGB. Unless the software can determine the colour space used in the image file and use this information, sRGB it is. The second issue is device capability. Many (if not most) computer screens on the market can't even reproduced sRGB at the high end, there are screens that can accurately display up to the full Adobe RGB colour space. All out of gamut colours need to be handled so that the display can show them and printers can print them, which is what the rendering intents take care of.

[DanK]

A complication, I think: Pointer’s gamut is the full range of reflected colors we perceive. Emissive devices can emit hues outside of it, no? This could be relevant for some urban night photography, although I can’t say I’ve ever worried about getting the color of a neon sign precisely correct.


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[xpatUSA]

A useful app is ColorThink where the gamut of any capture can be displayed against several color spaces, 2D or 3D.

Ed, here's a landscape mostly green, earth tones and a bit of sky:



It is a JPEG from a raw edited in ProPhoto working space and saved with an embedded ProPhoto profile. Should look OK on your monitor.

Here's the gamut of that image super-imposed on the sRGB gamut which in turn is super-imposed on the CIE gamut of human vision diagram.



As you can see, all the image colors are within the sRGB triangle except one which is just on the edge at the top.

This post is illustrating that normal scenery is quite OK in sRGB in spite of any shock or horror expressed elsewhere ...

[Manfred M]

Which part of what I typed is not true? I ask not in any querulous way but because if I have got somethng wrong I'd like to correct it!

If you meant that there's more to it than what's in my post, yes, I agree.

I guess I was not clear enough in my response in #15.

I use an Adobe RGB compliant screen, so it can accurately display virtually the entire Adobe RGB colour space. It is 99% Adobe RGB compliant and given that it is a few years old, it was the best compliance at on the market at that time. Currently there are some 100% Adobe RGB screens on the market and if I were to replace the screen, I would likely select one of those.

Like Dan, I am a print maker using a higher end ink jet photo printer, so using a wide gamut screen makes sense to me. Like Dan, I select the paper I use to give me the best quality output. Knowing that the colour is "right" takes away one of the variables of post-production and print making.

Does all this matter in "real life". The answer is yes. Ask any commercial photographer what their client would say if the company logo or product colour was not correct. Ask any wedding photographer, who is facing an irate mother-of-the-bride because the colour of her outfit are not "correct".

[xpatUSA]

I don’t work in a wide gamut because it’s more fun or because I worry about being left behind. I do it because sometimes—not always, by any means—it gets me better-looking prints. It’s the same reason I have spent a lot of time carefully picking the papers I use.

If you mostly post on the web and print only casually, it may not make an appreciable difference for you.

On the other hand I do find that, by staying in sRGB during conversion from raw, out-of-gamut stuff is easily spotted by bottomed or clipped channel values - for example a red flower with all it's green channel values at zero ... but I don't print much.

[Manfred M]

A complication, I think: Pointer’s gamut is the full range of reflected colors we perceive. Emissive devices can emit hues outside of it, no? This could be relevant for some urban night photography, although I can’t say I’ve ever worried about getting the color of a neon sign precisely correct.

Agreed Dan. Pointer's gamut deals with reflected light, not emissive light.

It's more than just neon lights too. I've had out of gamut problems when photographing fireworks, events with theatrical lighting, etc.

I'm not sure of what illumination that Pointer used when he came up with his colour space; are these the colours that we see in natural daylight (with some adjustment for latitude and time of day?). I expect gels used in stage lighting are unlikely to show up in his modeling.

[Abitconfused]

Thank you all for your input. ALL my questions have been answered! I can rest now and relax on my yacht in the harbor of Monte Carlo while sipping cool drinks and chatting with super models.