Clarification on Color Management (Working Spaces and Rendering Intents)

[tthaley]

I'm confused over what working space I should be using in various programs throughout my workflow and what rendering intents are used.

Lightroom 5 uses ProPhoto RGB for the develop module. If I shoot my photos in Adobe RGB wouldn't I want to work in this color space in Lightroom? What rendering intent is used to convert to ProPhoto RGB? Does it maintain the original colors?

On export to Photoshop, should I stay with ProPhoto RGB, or can I convert to Adobe RGB without losing accuracy? Again, what rendering intent is used?

Also, no monitor can display ProPhoto RGB, so what is the point of using this working space? My monitor can't even display Adobe RGB (it does 77%). How does the video card go about converting between the working space and the monitor gamut (what rendering intent does it use)? Can I trust my monitor to display an adequate approximation to Adobe RGB, or should I use the sRGB working space?

[Colin Southern]

Tom,

Are you shooting RAW or JPEG?

[Polar01]

Tom good questions, now it takes some time to wrap you head around the answers, lord I know I did. If you are working with RAW files it does not matter what you set you camera to, when you bring your files into LR is defaults to the ProPhoto work space. Now if you are using Adobe Camera Raw (ACR) if you note the line in blue at the bottom of your image click on it, once open you can set the colour space, the bit depth, and the resolution. Done once these setting can on for all images opened afterwards unless you go in and change the settings.
Once exported from LR to Photoshop you need to change nothing.
You can only trust you monitor if you have had it profiled, then you know that the colours you see it are correct.
I will let others talk more, who have a better understanding and are able to explain in words better than I.

Cheers: Allan

[tthaley]

Tom,

Are you shooting RAW or JPEG?

14-bit RAW

[Colin Southern]

Lightroom 5 uses ProPhoto RGB for the develop module.

Yes.

If I shoot my photos in Adobe RGB wouldn't I want to work in this color space in Lightroom?

Since you're shooting RAW, you're not shooting an any colourspace; a colourspace can't be applied to a RAW file until it's converted, and that conversion happens outside of the camera. The sRGB / Adobe RGB setting only affects in-camera JPEGs.

What rendering intent is used to convert to ProPhoto RGB? Does it maintain the original colors?

N/A since no conversion is being done.

On export to Photoshop, should I stay with ProPhoto RGB, or can I convert to Adobe RGB without losing accuracy?

It's up to you. From spiderman we have the great quote "with great power comes great responsibility" - and colourspaces are a bit like that in that the bigger the colourspace the bigger the mess people can find themselves in if they don't know how to handle it correctly (because it's possible to create colours that display as something else and print as something else again); so that's the downside of the bigger spaces like prophoto -- the upside is that they're caplable of containing most of the colours that the camera is capable of capturing. Often those colours are not as significant as people think though.

Again, what rendering intent is used?

Whatever is set in Photoshop - normally Relative Colorimetric.

Also, no monitor can display ProPhoto RGB, so what is the point of using this working space? My monitor can't even display Adobe RGB (it does 77%).

It preserves all colour information so that at a later data we may be able to display more of the colours captured, but other than that, not a lot. It's a moot point though because if you're going to use LR then that's all they use.

How does the video card go about converting between the working space and the monitor gamut (what rendering intent does it use)?

The system will convert on the fly using the active monitor profile, which will only be accurate if you've used a colorimeter and produced a custom profile (which every serious photographer should do as a priority if they're serious about their work).

Can I trust my monitor to display an adequate approximation to Adobe RGB, or should I use the sRGB working space?

It's not so much the approximation of Adobe RGB that you need to be concerned about as it is the colours that are out of gamit in sRGB but in gamut in Adobe RGB that you're trying to display, but they're not as common as people think (but they definitely do still exist). At the end of the day you can't really "approximate them" as they're colours that the monitor just isn't physically capable of reproducing.

In real-world terms it comes down to whether you're printing or not; sRGB is fine for displaying images -- some colours won't reproduce accurately, but most won't notice and even if they do it's "too bad" because sRGB is still the most common denominator on the net. If you're printing though then you really need to invest in an Adobe RGB capable monitor unless you're very "clinical" about how you're handling your colours because you'll be printing colours that you can't display -- so you have to resist the temptation to adjust them by eye.

But to answer the question - no - don't use sRGB as the working space; you're better off keeping things in Adobe RGB or prophoto -- just be sure to convert to sRGB for internet display or commercial printing, and DON'T convert any to sRGB if you're doing your own printing.

Hope this helps.

[ajohnw]

I'm confused over what working space I should be using in various programs throughout my workflow and what rendering intents are used.

Lightroom 5 uses ProPhoto RGB for the develop module. If I shoot my photos in Adobe RGB wouldn't I want to work in this color space in Lightroom? What rendering intent is used to convert to ProPhoto RGB? Does it maintain the original colors?

On export to Photoshop, should I stay with ProPhoto RGB, or can I convert to Adobe RGB without losing accuracy? Again, what rendering intent is used?

Also, no monitor can display ProPhoto RGB, so what is the point of using this working space? My monitor can't even display Adobe RGB (it does 77%). How does the video card go about converting between the working space and the monitor gamut (what rendering intent does it use)? Can I trust my monitor to display an adequate approximation to Adobe RGB, or should I use the sRGB working space?

One thing I don't have a grip on as it's never been of interest is if setting aRGB instead of sRGB in the camera changes the raw files at all. I suspect it just changes the jpg's.

Another way of putting the reason for 3x16bit working colour spaces is as follows.

The workspace is where the "information" is. Adobe RGB or sRGB are what is actually displayed on the monitor. The workspace has 3 16 bit colour channels against the displays 3 8 bit channels. This means that fractions of the 16bit space can be PP's into the 8 bit space. The 8 bit space has 256 possible values so can only be manipulated in units of 1 of the 255 steps. The 16bit space has 256 times as many steps so each of these tiny steps can be manipulated into the 8 bit space. That isn't the main advantage though. To see what that is there is a need to know what happens to the data from the camera. Ignoring prophoto final output which some do use at times this is

Raw -> Camera Profile -> 3x16bit colour -> Post Processing -> Paper/Printer/Monitor Profile -> 3x8 bit colour

If the workspace was 3x8 bit the 16 bit number will have been truncated and the extra information thrown away and can't be recovered as it's gone for ever. If the work space is 16 bit and PP's into the 8 bit one the 16bit space still has enough information to undo what ever had been done. The 16 bit can also be converted into a number of different styles of colour space via printer and monitor profiles. aRGB for instance is basically a profile intended for printing. sRGB for displaying on a screen. In practice 16bit doesn't really offer any advantage over 8 in respect to different outputs. It just needs more care when the raw file is converted to the 8bit space. In the extreme that may mean doing a raw conversion for each colour space that is needed.

People who want a prophoto output adjust without actually being able to see the final colours that will be produced until it's printed.

A modern way of expressing all of this is that ProPhoto is the transport format so when ever the information is transported between packages it should be used. Another is beginning to emerge 3 x 32bit floating point colour channels. 32 bit floating point is loosely equivalent to 6 or 7 decimal place precision - off the top of my head. A lot more possible values than even 16 bit channels. Again the justification is never loosing data.

John
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[Colin Southern]

One thing I don't have a grip on as it's never been of interest is if setting aRGB instead of sRGB in the camera changes the raw files at all.

There's no such thing as "aRGB" - I think you mean Adobe RGB

[ajohnw]

There's no such thing as "aRGB" - I think you mean Adobe RGB

I think there should be as it saves typing.

John
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[DanK]

Tom,

Like you, I shoot raw, so the camera setting is irrelevant. My general rule of thumb is to leave everything in ProPhoto until I have a reason not to, just to avoid losing data. In Lightroom, of course, it is not an issue until you export an image. When you print, LR does the conversion to the printer's color space on the fly, so there is no reason to fuss with a conversion beforehand. I've just gotten in the habit of leaving my two external editors (Photoshop and Zerene) in Prophoto as well. Out-of-gamut colors are primarily an issue only in printing, since the software has to convert to sRGB to display on my monitor, so I see what the sRGB image will be. For printing, I rely on soft proofing in LR to show me out of gamut colors, given my printer and the particular paper, and make adjustments at that stage.

If you are using a lab for printing, ask them what they want. Most want sRGB, but some will take Adobe RGB as well.

Dan

[ajohnw]

Tom,

Like you, I shoot raw, so the camera setting is irrelevant. My general rule of thumb is to leave everything in ProPhoto until I have a reason not to, just to avoid losing data. In Lightroom, of course, it is not an issue until you export an image. When you print, LR does the conversion to the printer's color space on the fly, so there is no reason to fuss with a conversion beforehand. I've just gotten in the habit of leaving my two external editors (Photoshop and Zerene) in Prophoto as well. Out-of-gamut colors are primarily an issue only in printing, since the software has to convert to sRGB to display on my monitor, so I see what the sRGB image will be. For printing, I rely on soft proofing in LR to show me out of gamut colors, given my printer and the particular paper, and make adjustments at that stage.

If you are using a lab for printing, ask them what they want. Most want sRGB, but some will take Adobe RGB as well.

Dan

Also worth adding that many lab printer outfits will provide profiles for the paper they use. The basic idea of soft proofing is to use profiles which will persuade the monitor to display the end result when it is actually printed. End to end colour management can get pretty complicated.

Long term digital image storage for posterity tends to go along the lines of only using none proprietary formats that can include colour management. Uncompressed TIFF is a favourite as far as conservators are concerned. They are also prepared to accept Adobe DNG as this is an attempt to get away from different makes of cameras having different raw file formats and Adobe have made it's use freely available. Just like aRGB ( sorry Colin ) They are basically saying the main aspect is that a completely specified format is used and it's royalty etc free. Odd that some put png low down their list as it only exists because of rights issues.

John
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[Manfred M]

Dan - my workflow is very similar to yours, and while I don't use Lightroom very often, the default colour space setting I use in Photoshop is ProPhoto.

All of my Photoshop files are saved; layers intact, ProPhoto colour space and with import and in-process sharpening completed.

The final steps before I output, which I always throw away after the final image is completed is to flatten the image and convert to the output colour space (Photoshop does this automatically when I go to a different color space, the way I have set things up) and then do the output sharpening. Once the final image is produced, I save that and throw anything done during these last steps in order to preserve the more data rich file.

Throwing away any data (like going to sRGB and jpeg) should always be the very last steps in anyones output workflow.

[Colin Southern]

Also worth adding that many lab printer outfits will provide profiles for the paper they use. The basic idea of soft proofing is to use profiles which will persuade the monitor to display the end result when it is actually printed.

For what it's worth, I find soft-proofing:

Useful - in terms of using the out-of-gamut alert (so potentially problem areas are highlighted), but

Useless - in terms of "simulating" output on another device. At the end of the day, RGB monitors and CMYK printers only have a certain gamut in common -- outside of that it's hopeless because one just isn't physically capable of reproducing colours on the other, and thus becomes a "lost cause".

[ajohnw]

For what it's worth, I find soft-proofing:

Useful - in terms of using the out-of-gamut alert (so potentially problem areas are highlighted), but

Useless - in terms of "simulating" output on another device. At the end of the day, RGB monitors and CMYK printers only have a certain gamut in common -- outside of that it's hopeless because one just isn't physically capable of reproducing colours on the other, and thus becomes a "lost cause".

Does that apply to a printing lab sRGB printers Colin? Don't suppose I ever will use one but if I did I would obtain their paper icc file and see just what it did.

John
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[Colin Southern]

Does that apply to a printing lab sRGB printers Colin? Don't suppose I ever will use one but if I did I would obtain their paper icc file and see just what it did.

John
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Sorry - Yes, soft-proofing would probably work OK for sRGB "lab" printers (I was thinking CMYK "DIY" Printers), but I suspect that the advantages to be gained are probably insignificant since they're more or less the same gamut and either on "non-radical" paper (in which case they'll look the same without soft-proofing) or on some of the more "radical" papers in which case they probably won't simulate that well anyway.

I know that when I've tried simulating canvas with soft-proofing the results are just meaningless.

In the real world - personally - I like to know of any potential areas that are out of gamut so I can possibly do something about it before printing, but after that "she prints how she prints". In reality the good results come more from experience of knowing how particular media performs (eg canvas with photo ink has a high black point (around 20 unsprayed) and I know from experience to clip the blacks and whites quite aggressively to get good-looking contrast (typically 8 to 16 for the blacks and down to as low as 235 for the whites) -- soft-proofing just doesn't show that (probably due to the differing dynamic ranges).

[tthaley]

colourspaces are a bit like that in that the bigger the colourspace the bigger the mess people can find themselves in if they don't know how to handle it correctly (because it's possible to create colours that display as something else and print as something else again); so that's the downside of the bigger spaces like prophoto -- the upside is that they're caplable of containing most of the colours that the camera is capable of capturing.

What colors are the camera able to capture, in general? Does it matter if the camera gamut is larger than Adobe RGB?

[ajohnw]

Sorry - Yes, soft-proofing would probably work OK for sRGB "lab" printers (I was thinking CMYK "DIY" Printers), but I suspect that the advantages to be gained are probably insignificant since they're more or less the same gamut and either on "non-radical" paper (in which case they'll look the same without soft-proofing) or on some of the more "radical" papers in which case they probably won't simulate that well anyway.

I know that when I've tried simulating canvas with soft-proofing the results are just meaningless.

In the real world - personally - I like to know of any potential areas that are out of gamut so I can possibly do something about it before printing, but after that "she prints how she prints". In reality the good results come more from experience of knowing how particular media performs (eg canvas with photo ink has a high black point (around 20 unsprayed) and I know from experience to clip the blacks and whites quite aggressively to get good-looking contrast (typically 8 to 16 for the blacks and down to as low as 235 for the whites) -- soft-proofing just doesn't show that (probably due to the differing dynamic ranges).

I was just curious in case I do ever have anything printed Colin. I've played with a sRGB laser printer without calibration but only up to A4. I haven't dealt with colour on a daily basis which would mean that while I can't see much in the line of a colour shift you probably would. I'm slowly getting more picky about the colours that come out of the camera though. Not sure if this is good. It leaves more work to do.

John
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[DanK]

What colors are the camera able to capture, in general? Does it matter if the camera gamut is larger than Adobe RGB?

Tom,

The camera does capture more than sRGB and Adobe RGB. That is the point of using prophoto--it does not discard (or at least discards less) of the information the camera has captured. You toss out quite a bit to get to adobe RGB and more yet to get to sRGB. The reasons for not discarding the information are explained in the earlier posts.

Dan

[Manfred M]

Tom - the issue is not the camera; it can capture a lot more colours than a computer screen can display or a colour printer can reproduce.

Gamuts are related to these output devices. For instance, sRGB incorporated all of the colours of a previous generation of computer screen could reproduce and is still the defacto standard for images posted on the Internet. If you have a lower end TN type display, it can only reproduce the sRGB gamut. Higher end IPS type displays can handle most if not all of the Abobe RGB gamut.

Adobe RGB was developed to cover off the additional colours that more recent screens and printers could handle. I have a higher gamut screen and the spec states that it can display 100% of the sRGB gamut and over 95% of the Adobe RGB color space.

ProPhoto is a more recent colour space and can pretty well all real-world colours, even though output devices cannot reproduced them, making it the obvious choice when doing post-processing work using RAW image data.

[Colin Southern]

What colors are the camera able to capture, in general? Does it matter if the camera gamut is larger than Adobe RGB?

Not something I've paid a lot of attention to to be honest, but colloquially I can recall that at least some can capture a slightly wider range than Adobe RGB. In reality it's simply a non-event though, as you'll never ever see the difference, so best just to ignore it and focus on more important things like device profiles, sharpening etc, which will have a far far far far greater impact on the finished image.

[Richard Lundberg]

The OP asked about rendering intents. All renderings are relative colorimetric unless the receiving profile has the others. This is not the case in Photoshop for screen display, although your prints will reflect whatever rendering intents the printer driver and output profiles will support. I just got LR 5 so I am not sure whether its aRGB and sRGB have the other intents. There is an sRGB profile available on the ICC site that allows other intents, but you have to install it and make sure you are using it. The installed profiles for Photoshop PSCS5 do not have any intent except relative. I do not have PSCS6 or CC so I do not know if they have v4 profiles for aRGB and sRGB that allow the other intents.