As I mentioned, been there done that. And I could not demonstrate it. It's great you trust "logic", but logic doesn't always equate to reality. And I don't know why it's up to anyone else to demonstrate your point of view (and in fact I don't think it can be done ... well, never say never but if so the circumstances would probably be extremely rare and unique.)
I really don't care if you or anyone else attempts to prove or disprove me ... it's just that Andrew keeps on at me to
PROVE my point. I feel no need to do so beyond what I've already done. I also agree with you that demonstrating the issues with prints is very difficult ... which is why it's a very good idea to understand what is happening under the hood.
Well, the reasons the for the existence of sRGB and AdobeRGB have nothing to do with a photographers workflow and providing an "intermediate option. They were created for specific purposes that have nothing to do with a photographers workflow and current technology. (as opposed to ProPhotoRGB which was specially created for digital capture/printing technologies to be future proof, so the main goal was to try and make sure all naturally occurring colors could be defined).
Funny you should say that when Adobe RGB was created by Adobe, specifically to address photographic needs that went beyond the (hardware-driven) sRGB space.
And you should know, surely, that ProPhoto does NOT define all naturally occurring colors (or more correctly, all colors that we can see). Here is a simple demonstration of that:
ProPhoto is the triangle, the horseshoe is the typical extent of human vision. ProPhoto not only does not cover all of human vision, but it goes beyond to what (probably) no-one can see. The reason for it is to cover a large chunk of human vision ... but why did they stop where they did? Why not go the whole hog and cover the whole of human vision, accepting that with a triangular gamut this will (as does ProPhoto) include colors outside our vision? Seems to me that if you want big, ProPhoto just isn't big enough!
The mapping is relative to the distance the colors are out of gamut which is rarely that extreme.
Well, with Perceptual the mapping is relative to the gamuts (unless the profile maker cheats a bit and does a mix of relative/perceptual).
And I think most photographers don't use perceptual that often ... guessing I use it only about 5% of the time. And when I do, starting over in a smaller space which may contain the gamut of the file doesn't equate in a better image (tried that a few times over the years as well and I've never seen a visual difference)
Your images are probably not very saturated so you should be fine (you will be making very limited use of the additional gamut in ProPhoto). But there are photographers (or graphic designers and painters) who do use very saturated colors ... and for these perceptual may be better as it does attempt to preserve the relationship between the colors, whereas relative will clip the OOG colors (which may look much worse).
But a perfect match to a display is never what I'm after.
Admittedly a perfect match is pretty much impossible because we are dealing with fundamentally different devices. However the goal should surely be to see what you are going to print and for your print to be as close as possible to what you saw. In my case I can say that (having spent quite some time coming to grips with it) that I can get an almost perfect match between my prints and my display. It's a revelation when you achieve that because you can then be confident that when you hit the button you'll get the print you want.
It is of course true that this matching will only be correct for a particular viewing condition. However, fortunately our eyes adapt to different lighting and compensate to a large extent automatically, so on the whole if the print looks good under one light it will most likely look good under another.
And when you mentioned "clipped" colors because they are saturated, the colors we are talking about are extremely important because they help you pull open the shadows. To me that's the most important aspect of what the current printers offer in expanded gamut. But you can't do that in aRGB.
Of course if you've clipped the colors you aren't going to get them back! If you want to pull open the shadows you should absolutely do this at the raw conversion stage ... don't even wait to have your image in ProPhoto because at that point you've lost data already.
The discussion really boils down to two points. From your first post "If you go for a larger working space like ProPhoto you are really asking for trouble (this is entirely my opinion!)". I don't believe that opinion is shared by many, and I believe is very misleading. Anyone who will get into trouble with this workflow with modern raw processors and photoshop will get into trouble anyway. Secondly, whether or not using ppRGB for files which can be contained in smaller spaces is detrimental to the final image, and working in a space closer to the size of the data will deliver a better result (print). And perhaps while theoretically true, I"ve never seen anyone be able to demonstrate this. This second point is really where the main discussion has ensued, and I'm not sure why we should accept your opinion (and perhaps that of a few others) when empirically through printing hundreds of images over the years we've never seen any evidence to support the idea.
If you know what you're doing then ProPhoto is fine. My original response was to this post by mstevensphoto who asked: "
Hi all, I'm reading my literature and see that the ipf8400 has a 5-6% wider gamut but I don't see any comparison of the printer to the sRGB space. Does anyone know if it is able to print more colors than are in srgb (thus making me work in adobe98) or how the two line up?" With all due respect to mstevensphoto, he, like a great many photographers, clearly doesn't know much about working spaces or he would not have asked the question. The fact is that the iPF6400 has a much bigger space than Adobe RGB and also a much smaller space than sRGB ... depending on what papers you print on and what part of the image you are looking at (for example, the printer doesn't come close to sRGB at the dark end on a matte paper).
So, if you are responding to someone who doesn't really understand the pros and cons of workspaces ... would you recommend ProPhoto? Not me. Or at least if I did I would accompany the recommendation with information on what to do to make sure that he doesn't unknowingly ruin his images by going way out of gamut.
Agreed no point in taking this any further. Great you trust logic, but logic and even scientific evidence don't always equate to something that matters.
Are you a member of the Flat Earth Society?
That's where I think we disagree the most, you believe that this is an issue, where most would feel it's not anything to be concerned with because you just can't see the difference.
All you can say here is that YOU can't see the difference. Our eyes vary hugely in their ability to detect subtle color differences.
As far as demonstrating it, you are the one who is challenging current thinking and practice and telling others your way is better, wanting people to accept it on "logic" and some theoretical math.
Whose 'current thinking and practice', and is this the best practise? Andrew's, yes ... who else who considers themselves experts in color management? Bruce Linbloom, maybe (makes you wonder why he created Beta RGB!
http://www.brucelindbloom.com/index.html?BetaRGB.html).
I don't want people to accept what I say. I'm a scientist by training and I firmly believe that we should all come to our own conclusions based on the evidence we are presented with. And yes, I do think that logic and maths is one of the best ways of cutting through the bullshit. It's not like we're talking theoretical physics and sub-atomic particles here ... we are talking in the realms of 2+2=4, and there is no arguing with CMS mapping algorithms: these are computer programs and they are cast in concrete, so to speak. As Jeff Schewe said in one of his post or essays or something, GIGO! Garbage in Garbage Out. If you send garbage to your printer, expect a less than optimal result. Looking at the profile and seeing how well this encompasses your image gamut is one very good test of the integrity of what you will be sending to your printer.
The problem we have is that we don't know (at least I don't) XRite's algorithms (for example). However we can totally know ArgyllCMS's algorithms because Graham Gill has very generously made his software open-source. I think few people would argue that his algorithms are inferior to XRite's (unless the person is an XRite employee, perhaps). On the contrary, a bit like RawTherapee, ArgyllCMS has a wealth of options that are simply not available with XRite and which, for example, give us the possibility of generating image-specific profiles. There are very few systems out there at the moment that have that level of sophistication.
But if you can't show it, then is it really an issue to be concerned with? Maybe it is there, but if it were a problem, you would think it would confound and frustrate many people over the years that would cause us to rethink our workflows (as using ppRGB instead of theses other spaces did at one point in time).
If there were an easy way to do it, maybe it would be worth doing (still doubting it). But I just can't see any reason to muck up the workflow trying to figure out if my image needs to be in ppRGB, or whether sRGB or aRGB might be enough. No point, because just staying in ppRGB isn't a problem.
I think I have shown that there is an issue, or at least a potential one. A very simple case was very nicely demonstrated by Andrew when he (very unkindly) did a relative colorimetric conversion of a ProPhoto image to sRGB (in his video): he chopped the top off the poor image's head and ended up with something that looked as flat as a pancake. Where he went wrong is in blaming sRGB for that: the fault was his, not sRGB's.
If you're happy with ppRGB then totally fine ... I have ABSOLUTELY NO problem with that. I am NOT trying to convince you, or anyone, else to change. I am just attempting to correct what I think is misinformation.
Robert