calling all color whizes: non-typical sRGB/RGB/ProPhoto question

Started Dec 31, 2010 | Discussions
gongtrip New Member • Posts: 3
calling all color whizes: non-typical sRGB/RGB/ProPhoto question

Ok so I understand the fundamental differences of srgb, adobe rgb and prophoto rgb and I understand that working in adobe rgb or prophoto rgb theoretically gives you a wider color gamut to work with or in the case of prophoto also a greater bit depth, but what I don't understand is why would you do this if your monitor can only display the srgb gamut? If you can't see the wider spectrum of these color spaces what is the point of using them. Frankly, making adjustments to an image that I can't necessarily see would make me a little nervous. What am I missing here?

I guess the one situation I can understand is if you are doing extremely intensive effects work and want to use the greater bit depth of prophoto to minimize possible color artifacts but beyond that are these color spaces really a benefit?

Say a printer can print the entire adobe rgb gamut, again what is the point of working in this space unless you own a specialized monitor that can display the entire rgb gamut? In effect, wouldn't your srgb monitor just be clipping the most saturated colors such that you don't really know how colors beyond the srgb gamut limit will look in the final print?

Another thought, since adobe rgb is also an 8 bit space like srgb, but has a wider gamut, the discreet steps between color values would be less discreet would they not? So it seems to me that working in this space would gain you a greater range of super saturated colors but would be at the expense of losing some amount of subtlety in the overall tonal values. Am I envisioning this correctly?

Deleted1929 Forum Pro • Posts: 13,050
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

Frankly, making adjustments to an image that I can't necessarily see would make me a little nervous. What am I missing here?

IMO, you've spotted the insanity in some of these things.

This is a link to a website that I find very useful. The article on RGB working spaces is quite interesting. Notice that Prophoto and the WideGamutRGB spaces are significantly larger than the LAB reference space ( which effectively renders them useless ).

http://www.brucelindbloom.com/

In practical terms the vast majority of people would not need more than sRGB and anything else will complicate their lives to little or no practical advantage.

Some people, mostly pros or very serious amateurs, can make effective use of a slightly larger space, like AdobeRGB. However not all images will benefit from this larger space and I'm frankly doubtful most people would notice if you didn't use it. I know that's heresy, but a double blind test for appreciating a set of images would be interesting.

I'm not talking about colour accuracy here, I'm talking about the viewer experience of the image. As I like to remind people starting out post processing, there's accurate colour and there's pleasing colour and they don't often coincide.

Of course some photographic applications require high colour accuracy - reproduction of art work, for example. However I still don't see any purpose served in working in a colour space larger than your final output media can contain.

My view is that we should work in a colour space matching the gamut of our target output media. Surely this is just common sense ?

I have no idea why anyone feels the need to dive into even larger spaces. Until there is a practical benefit to this it does seem rather pointless and really complicates editing.

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StephenG

apaflo Veteran Member • Posts: 3,854
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

gongtrip wrote:

What am I missing here?

Nothing. You've nailed it.

Simon Garrett Veteran Member • Posts: 7,344
A few clarifications

gongtrip wrote:

Ok so I understand the fundamental differences of srgb, adobe rgb and prophoto rgb and I understand that working in adobe rgb or prophoto rgb theoretically gives you a wider color gamut to work with or in the case of prophoto also a greater bit depth,

That's confusing two issues. Yes, Adobe RGB has a wider colour space than sRGB, and ProPhoto RGB wider than Adobe RGB. But bit depth is separate. You can have any bit depth in any colour space.

However the jpeg image format allows only 8 bit representation.

but what I don't understand is why would you do this if your monitor can only display the srgb gamut? If you can't see the wider spectrum...

As an aside, "spectrum" is a misleading term here, and not correct

...of these color spaces what is the point of using them. Frankly, making adjustments to an image that I can't necessarily see would make me a little nervous. What am I missing here?

Not much point in adjusting colours that are outside the gamut of the monitor, but if your printer can display them, then it doesn't necessarily matter that your monitor can't.

I guess the one situation I can understand is if you are doing extremely intensive effects work and want to use the greater bit depth of prophoto to minimize possible color artifacts but beyond that are these color spaces really a benefit?

As I say, bit depth is nothing to do with colour space. I'd recommend that you edit in 16-bit colour, as the maths is more accurate, whatever colour space you are using. Even if you use only jpeg (which is 8-bit), editing in 16-bit and then saving in 8-bit results in more accuracy.

But if you start with an sRGB jpeg, then absolutely no point in converting to anything wider. You can't add colours that aren't there to start with.

Say a printer can print the entire adobe rgb gamut, again what is the point of working in this space unless you own a specialized monitor that can display the entire rgb gamut? In effect, wouldn't your srgb monitor just be clipping the most saturated colors such that you don't really know how colors beyond the srgb gamut limit will look in the final print?

Your monitor will display only colours within its gamut. But that doesn't "clip" colours in the image file. They're still there - you just can't see them on your monitor. If you're saying that your monitor must always have wider gamut than your printer - well, why?

Another thought, since adobe rgb is also an 8 bit space like srgb, but has a wider gamut, the discreet steps between color values would be less discreet would they not?

Yes, in 8 bit. As I say, you can also have 16 bit (or even 32 bit) sRGB and Adobe RGB images. But I agree with what you say, that the colour steps are wider in wider colour spaces. That's yet another reason for not converting sRGB images into a wider colour space, even for editing, unless your editor uses at least 16 bit resolution. (Lightroom does, it's optional in Photoshop.)

So it seems to me that working in this space would gain you a greater range of super saturated colors but would be at the expense of losing some amount of subtlety in the overall tonal values. Am I envisioning this correctly?

Yes, if you use 8-bit. Personally, I think it's bonkers to edit in less than 16 bit.

Personally, I think the benefits of colour spaces other than sRGB are rather hypothetical in most cases. The vast majority of pixels in the vast majority of images are within the sRGB colour space. The colours outside sRGB are highly-saturated and relatively uncommon in nature. Some bright flowers, perhaps.

As an example: My D300 has a native (raw) colour space of at least Adobe RGB, and I have around 25,000 raw images in Lightroom. I have two (calibrated/profiled) monitors, one wide gamut (roughly Adobe RGB) and one roughly sRGB. Lightroom normally displays images on both at once, and in only a tiny percentage of my photos (perhaps 1 percent) can I see any visible difference in the wide-gamut monitor. Presumably the rest are entirely within sRGB, or only small, imperceptable areas outside it.
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Simon Garrett Veteran Member • Posts: 7,344
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

sjgcit wrote:

Notice that Prophoto and the WideGamutRGB spaces are significantly larger than the LAB reference space ( which effectively renders them useless ).

In order to represent the entire CIE LAB colour space (in other words, the limits of average human colour perception), if you use RGB then you end up with a co-ordinate system that goes beyond the CIE space. That's just the maths. Clearly RGB values that are outside the CIE space are "useless" but I wouldn't say that makes ProPhoto RGB as a whole useless.

In practical terms the vast majority of people would not need more than sRGB and anything else will complicate their lives to little or no practical advantage.

I quite agree. Few natural (as opposed to artificial or computer generated) photographs will have any colours outside sRGB. Furthermore, our eyes are not very sensitive to differences in colour in highly saturated colours, so the loss of colours beyond sRGB is not very significant.

My view is that we should work in a colour space matching the gamut of our target output media. Surely this is just common sense ?

If you mean the working space of our software, I'm not sure that it matters so long as all conversions and processing are done in sufficient resolution. For example: Lightroom uses ProPhoto colour space. There's no choice. But you wouldn't know unless they told you. All processing and conversion are done at sufficient resolution that nothing is lost in the process.

I'd put it slightly differently: it's worth storing and processing an image in a colour space at least as wide as the widest colour space of any of the output devices you might want.

However, it's all a bit theoritical, I think. As we're both saying, anything beyond sRGB is of marginal utility.

PS - thanks for the link to Bruce Lindbloom - very interesting and informative!
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tony brown Veteran Member • Posts: 4,375
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

Another point arises, if you are going to do some heavy post processing, and you propose to work in the same colour space that you want the finished item viewed e.g. sRGB then you hit the following snag that would be overcome in a wider working colour space:

When messing with one colour, saturation, levels - even sharpening, you will frequently CLIP other colours etc in you work which, once clipped can't be recovered.

However, that doesn't occur to the same extent (if at all) in a wider space. Then when you have worked to the desired extent, you can convert to the final colour space and display. Thus, you would never see any lost detail in sRGB nor could you regain it subsequently. It's not so much a matter of seeing it on screen as it is not throwing away hard won data lest you need it before finishing.

Personally, I work in Adobe RGB at 16 bits for the safety margin and send, post or display in sRGB jpg (8-bit by definition) assuming that most will not be using space aware browsers/viewers. I guess most on this forum might be exceptions to that last assumption but that is to be expected on a Retouching Forum as it is in 'Printers and Printing'.

Cheers, Tony.

OP gongtrip New Member • Posts: 3
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

Been doing a little more research and in the interest of accurate information I should mention I was mistaken in my original post about ProPhoto being 16 bit. sRGB, Adobe RGB, and ProPhoto can all be edited in either 16 bit or 8 bit mode. It still holds true though I believe that for any given bit depth you are giving up discreet tonal value in lesser saturated areas of the gamut for greater overall color range when using a larger color space over a smaller one.

If you are capturing raw (or jpg in Adobe RGB instead of sRGB) then you are technically able to retain more of the super-saturated color information that is captured from your camera sensor's wide color gamut. However, you will not be able to actually see this extra color while editing. Your monitor will clip any colors that exist outside of its displayable color gamut which is probably a little larger than sRGB and a little smaller than Adobe RGB. Basically you are giving up certainty about the final appearance of the print for the possibility of a larger range of color in the print. Unless I'm still missing something, the increased range really only encompasses super-saturated colors anyways and it's at the expense of more subtle tonal rendition in the less-saturated areas of the color gamut. Technically you can soft-proof the image but you are still only guessing at how the printer (unless you can obtain that particular technical information for the particular printer model) will choose to handle the color information that still remains outside of IT'S printable gamut (which will probably be greater than your monitor's gamut but still smaller than Adobe RGB or Prophoto.)

It seems like the only advantages to using the larger gamuts would be if you have some crazy art project that consists of lots of subtle variations in a bunch of highly saturated colors. In terms of practical photography I don't think you are really losing any color information except in the extreme highlights where it would be barely perceptible anyways and probably just read as white to the human eye.

Please correct me if I'm wrong here!

frteskesc Regular Member • Posts: 230
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

I would not necessarily categorize color spaces into 8bit/16bit color spaces? Bit depth has to be taken into consideration when working in large color spaces but their is no strict dependency. One can work in an sRGB images in 16bit mode as one can work in ProPhotoRGB in 8bit mode.

Using larger color spaces is mainly in order to retain more colors. sRGB, AdobeRGB and ProPhotoRGB are device independend color spaces, although they have been created with certain needs in mind. sRGB, for instance, resembles the color capabilities of average monitors, whereas AdobeRBG has been created to meet the color capilities for printers in the printing process as it emcompasses the color space of most printers.

Sure, it is hard to soft proof those extra colors on a monitor with a smaller color gamut, but it doesn't mean your output device (printer) cannot benefit from it. BTW, wide gamut monitors (close to AdobeRGB) are not that expenisive anymore. So, with a good monitor and a good printer using AdobeRGB color space could be an advantage.

But as I said earlier. These color spaces are device independend. Especially for archiving you might want to retain as much information as possible. You don't know which output device you want to use and you never know what future devices are capable of. A large color space like ProPhotoRGB might be the right choise for the future.

Of course all this doesn't come for free. Color management can be complex and confusing, so it is hard to give a general recommendation.

OP gongtrip New Member • Posts: 3
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

oh wow, looks like a flurry of posts while i was working on my last response. Good to see it looks like I'm on the right track. Thanks for all the great information guys!

Zaldidun Veteran Member • Posts: 4,092
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

gongtrip wrote:

…Good to see it looks like I'm on the right track…

That's hilarious and certainly self serving, but you're clueless, actually.

You've been told so in the other two forums where you posted the same OP., which is not cool.

z
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Zaldidun Veteran Member • Posts: 4,092
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

sjgcit wrote:

My view is that we should work in a colour space matching the gamut of our target output media.

Correct. Since my target media consists of photographic prints made on high-end Epson inkjet printers and/or Fuji Contone printers, I use ProPhoto RGB exclusively. These printers can print colors that are outside the gamut of even Adobe RGB, let alone the lowly sRGB (where we all know what the "s" stands for, right?).

I have no idea why anyone feels the need to dive into even larger spaces.

1.— So as not to lose colors you can print, as stated above;
2.— To have more leway and latitude when editing.

Here's a good analogy recently given in another venue: Your wallet can hold only so many bills. Do you throw away the rest of your money? (If you do, I'd love to know where.)

Until there is a practical benefit to this it does seem rather pointless and really complicates editing.

The practical benefit is explained above, in both parts of this post of mine. Far from "complicating editing" it allows for greater freedom while editing.

z

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« Zaldidun » is the Basque word for 'Horseman'.

Zaldidun Veteran Member • Posts: 4,092
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

sjgcit wrote:

Frankly, making adjustments to an image that I can't necessarily see would make me a little nervous. What am I missing here?

What you are missing are the various gamut warning controls in software like Photoshop plus the experience and skills to handle the colors the monitor does not show you.

z
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tony brown Veteran Member • Posts: 4,375
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

Zaldidun wrote:
....

Here's a good analogy recently given in another venue: Your wallet can hold only so many bills. Do you throw away the rest of your money? (If you do, I'd love to know where.)

You have made a fine argument in your posting except this completely irrelevant non-sequitur above. Itself, it makes no sense and it also has no similarity to the OP question.

Where is there any analogy? :)- Don't try and justify it, you will only loose ground. You were doing just fine without it.

Cheers, Tony.

Jack Hogan Veteran Member • Posts: 8,008
typical colors space question

gongtrip wrote:

What am I missing here?

Many, many weekends of in-depth reading: color theory is a very complex and interesting subject, but you will not get very far unless you put in the time. At the end you will have a much better idea of what it takes to create a superb color reproduction, you will have spent more money on a better monitor or two, a calibrator/profiler, better printer and you will have the nicest looking captures/prints in your neighbourhood - especially if you shoot a lot of parrots and canaries - and understand why.

Here is an outstanding link to get you started:
http://graphics.stanford.edu/courses/cs178-10/applets/locus.html

As far as your other questions are concerned, the monitor is but a window on the underlying image INFORMATION: a rising tide lifts all boats. If you are asking, I assume that you are shooting raw. The idea is to preserve and have available during post processing as much of the information that was originally captured as possible to have wider and firmer ground to build upon. You do that keeping your files in 16 bits throughout (except, by necessity, at output), in a medium sized color space that ideally JUST encompasses both your camera AND your printer's gamut and that you ideally never change from raw conversion to output. When you find one of those let me know. In the meantime I am sticking with MelissaD65 as a working space, with its ProPhotoRGB-sized color space, 2.2 gamma linearized near the origin, and D65 reference white.

Cheers,
Jack

Zaldidun Veteran Member • Posts: 4,092
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

tony brown wrote:
Zaldidun wrote:
....

Here's a good analogy recently given in another venue: Your wallet can hold only so many bills. Do you throw away the rest of your money? (If you do, I'd love to know where.)

You have made a fine argument in your posting except this completely irrelevant non-sequitur above. Itself, it makes no sense and it also has no similarity to the OP question.

Where is there any analogy?

The analogy : Your money are the colors your camera can capture and your printer can print. Your monitor is your wallet.

The absurdity is throwing away the rest of your money that does not fit in your wallet, i.e. throwing away colors your monitor does not display by going to a narrower color space.

No analogy is ever perfect, but this one actually comes very darn close to perfect.

Cheers to you too.

z

EDTED missing a in away.

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Simon Garrett Veteran Member • Posts: 7,344
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

Zaldidun wrote:

...let alone the lowly sRGB (where we all know what the "s" stands for, right?).

Standard. Although somehow I suspect that wasn't what you had in mind!
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Simon Garrett Veteran Member • Posts: 7,344
Re: typical colors space question

Jack Hogan wrote:

Here is an outstanding link to get you started:
http://graphics.stanford.edu/courses/cs178-10/applets/locus.html

Agreed, and in fact the whole course at http://graphics.stanford.edu/courses/cs178-10/schedule.html is worth going through. But hurry! Both links were there for the Spring 2010 course students, and might not stay there.
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Zaldidun Veteran Member • Posts: 4,092
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

Simon Garrett wrote:

Zaldidun wrote:

...let alone the lowly sRGB (where we all know what the "s" stands for, right?).

Standard. Although somehow I suspect that wasn't what you had in mind!

z
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« Zaldidun » is the Basque word for 'Horseman'.

Zaldidun Veteran Member • Posts: 4,092
Re: typical colors space question

Jack Hogan wrote:

…The idea is to preserve and have available during post processing as much of the information that was originally captured as possible to have wider and firmer ground to build upon. You do that keeping your files in 16 bits throughout (except, by necessity, at output)

??? …by "necessity" ?

Not necessarily.

The Macintosh version of Photoshop since Photoshop 11.x ( "CS4" ) allows you to print in 16 bits, which most—if not all— of the high-end inkjet and Contone printers can handle.

z

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Robin Casady Forum Pro • Posts: 12,898
Re: calling all color whizes: non-typical sRGB/RGB/ProPhoto question

gongtrip wrote:

It seems like the only advantages to using the larger gamuts would be if you have some crazy art project that consists of lots of subtle variations in a bunch of highly saturated colors. In terms of practical photography I don't think you are really losing any color information except in the extreme highlights where it would be barely perceptible anyways and probably just read as white to the human eye.

Please correct me if I'm wrong here!

Out of gamut images are often posted in this forum. I believe that it isn't as rare as you believe.

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