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  #1  
Old 01-06-2013, 06:21 PM
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iceman (Mike)
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Which Colour Space for processing?

What colour space do you guys use for processing?

I think I'd been using sRGB, but changed my colour space in Photoshop recently when the Malin awards wanted them in Adobe RGB 1998.

Now when I open some old jpeg's saved in sRGB, they just look terrible (in Adobe RGB1998) (darker in the shadows) than if I switch the colour space back to sRGB.

I guess it's a matter of being consistent over time and sticking with something, but of course then the printer wants a different colour space calibrated to their printers.

What do you guys use and how do you manage it?
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Old 01-06-2013, 08:16 PM
Garbz (Chris)
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Wowowowow!

If you've changed a colour space and now something looks wrong then you've done it wrong. The picture should not change as the result of changing the colour space. Think of it this way. Unless you have a monitor that can display more colours than sRGB then any conversion to any other colour space should show no change if converted correctly. The only time you should see a change is if going from a large colour space to one smaller than that of your screen (likely sRGB)

- Did you use "Assign Profile" to change the space? If so, don't. The only reason to ever use assign profile is if the profile was set wrong to begin with.
- You should use "Convert to Profile" whenever you're changing something.
- Also don't change any Colour Settings in Photoshop. This isn't required for using a different colour space. It is completely independent from your ability to set the current working profile (via Convert to Profile).

As for what I use and how I manage, I use AdobeRGB, but then I have a monitor which covers 97% of the AdobeRGB gamut so I have a visible improvement on the odd picture that's colourful enough to benefit from it. Ultimately though if I'm not printing a picture I'll save to sRGB, then there's no headaches when I give the pictures to someone else.
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Old 02-06-2013, 02:13 PM
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I use ProPhoto RGB for processing astro and conventional DSLR images. At the end of the process I convert to an appropriate colour space if needed (e.g. sRGB for web). There's a reasonable explanation of why you might want to do this here: http://www.luminous-landscape.com/tu...hoto-rgb.shtml

This has almost always worked well for me. The only time it didn't was when I processed an image of the Saturn Nebula. When I got to the end I discovered that the colours in the body of the neb were out of gamut for sRGB and I lost all the subtle detail when I converted

Cheers,
Rick.
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Old 02-06-2013, 06:25 PM
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philiphart (Phil Hart)
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Garbz is on the right track Mike.. but Colour Spaces is a bit of a mind-bender and I don't have my head around it fully either.

With Photoshop managing profiles I can convert between files between profiles or open the sRGB exported version of a RAW file and have it all look pretty similar (I don't notice a difference anyway).

However, if I view Adobe RGB images in ACDSee then they look flat, muted etc but that is an ACDSee issue (I might be able to fix if I looked into the settings).

The only time I've ever run into trouble is with my recent images of the bioluminescence.. I hadn't really investigated at the time but I had some out-of-gamut issues.. I think the monitor could not properly display some of the extreme blues in the ProPhotoRGB colour space file, so Photoshop warned me by blacking out those pixels. The sRGB exported images looked fine.

You prompted me to do some more reading and I found this article helpful:

http://dpbestflow.org/color/color-sp...color-profiles

Phil
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  #5  
Old 02-06-2013, 08:12 PM
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This thread mentions that colour space aware software such as PS convert the image on the fly to match the colour profile of the monitor.

That would explain why normal image viewers don't show the correct colours when displaying adobe RGB images.

Raw files have no colour profile, that's one of the biggest advantages of shooting raw, the ability to choose colour space at any time.

As far as I know you can't just swap colour space on a JPG file, you need to convert using a suitable tool.
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  #6  
Old 02-06-2013, 10:52 PM
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Originally Posted by philiphart View Post
However, if I view Adobe RGB images in ACDSee then they look flat, muted etc but that is an ACDSee issue (I might be able to fix if I looked into the settings).
You probably need to enable colour management in ACDSee. It appears to be an option... I'd strongly advise using a viewer which supports colour management and has it enabled unless you're planning to do everything in sRGB - and even then it's probably a good idea.

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Originally Posted by acropolite View Post
Raw files have no colour profile, that's one of the biggest advantages of shooting raw, the ability to choose colour space at any time.
Actually, they have a camera specific colour profile. When you choose a colour space you are doing a conversion from the camera specific space to the new one.

Cheers,
Rick.
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Old 03-06-2013, 09:51 AM
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I think this flow chart is helpful

http://www.imagescience.com.au/CONTE...3/image012.jpg

I process in aRGB, since my monitor supports it (99%) but i always export in sRGB for web and prints (unless the lab has a profile).

Calibration with a colorimeter every few weeks is important too.
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  #8  
Old 03-06-2013, 12:18 PM
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Thanks guys - got some reading to do.
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  #9  
Old 04-06-2013, 01:39 PM
Garbz (Chris)
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Quote:
Originally Posted by acropolite View Post
Raw files have no colour profile, that's one of the biggest advantages of shooting raw, the ability to choose colour space at any time.

As far as I know you can't just swap colour space on a JPG file, you need to convert using a suitable tool.
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Actually, they have a camera specific colour profile. When you choose a colour space you are doing a conversion from the camera specific space to the new one.
Almost right, just to extend this you can not ever swap colour spaces. You can only convert. There's no reason you can't do this with a JPEG just like you can with a RAW. Any colour managed program does this on the fly. If I open a JPEG in Photoshop then Photoshop will in realtime convert the colours to my monitor profile which it gets from the Windows settings. If I soft proof to a printer it will convert the JPEG to the printer profile and then back to the monitor profile allowing me to see the results of my printer's smaller colourspace will have on my colours.

Same with RAW. If I open a RAW file in Lightroom it will convert the RAW data to MelissaRGB (Lightroom's internal profile) using the Adobe DNG Profile for my camera, and then convert the resulting image to my monitor profile (in that respect the conversion to MelissaRGB is done once, whereas the conversion to my monitor profile is realitime).

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Old 08-06-2013, 07:33 PM
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Short answer - the ideal solution is to convert your source data into 16-bit (or higher) ProPhoto RGB as early as possible in your workflow, and use this for all your edits/storage. Convert to sRGB/aRGB as the final step, i.e. just before uploading the image to the print lab or posting online.

Long answer: sRGB should be obsolete because our consumer monitors, printers, and cameras can easily exceed its narrow gamut. However, since it's still widely used by non-colour management aware software (and people!), it's the de-facto standard online. However, many web browsers - even ones that should know better (I'm looking at you, Apple and Microsoft) - will ignore embedded colour profiles, so images for the web should be in sRGB.

Adobe RGB has a much wider gamut and seemed to be the colour space of choice for photographers in the past, e.g. when uploading to print labs, converting from camera RAW files, etc. However, it's also becoming obsolete because consumer equipment is starting to exceed its gamut. For example, monitors that advertise "97% of Adobe RGB" gamut usually also substantially exceed Adobe RGB in some parts of the spectrum.

ProPhoto RGB has a very wide gamut and is also widely used, though interestingly it still can't represent all of the visible colour spectrum. It's used by Adobe CS products internally, so for example in Lightroom if you open a RAW DSLR image (with edits applied) for editing in Photoshop, you'll notice that the default colour space is ProPhoto RGB.

I've attached a few images of gamut comparisons. In image #1, you can see how much wider ProPhoto RGB's gamut is, and how sRGB/AdobeRGB are readily exceeded (by a printer in this case). Image #2 shows the measured colour space of my archival pigment inkjet (solid) compared to Adobe RGB (wireframe) - the printer exceeds Adobe RGB in yellows/oranges, dark greens, and dark reds quite noticeably. Image #3 shows the measured colour space of my "99% AdobeRGB" desktop monitor compared to Adobe RGB - it can show pinks, reds, yellows, and greens well outside of Adobe RGB. I haven't profiled my DSLR/lenses yet, but others' results show that it's a wider gamut again than Adobe RGB.

The main downside of using a wider gamut colour space is that each shade-of-gray step in an 8-bit image represents a larger jump than it does for a narrower gamut such as sRGB. This means that your workflow needs to be at least 16-bits the whole way to ensure that you don't lose fine colour detail (compared with if you had used sRGB for editing). Unfortunately, JPEGs don't support 16 bits per pixel which often means storing DSLR images in TIFF or RAW format (with edits in metadata format, ala Lightroom).

For my own images, I edit in ProPhoto RGB for the whole workflow but convert to JPEG format with sRGB colour space for long term storage. My lifetime collection is already at 94 GB - of only "published" keepers, with no storage of RAWs or multiple sequence shots. It's definitely not ideal, but a smaller set of data is easier to "guarantee" longevity. (I keep my raw data on external drives, but I won't lose sleep if they die.)

Sorry for the long post - hope that helps!
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  #11  
Old 10-06-2013, 02:42 PM
Garbz (Chris)
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Quote:
Originally Posted by naskies View Post
sRGB should be obsolete because our consumer monitors, printers, and cameras can easily exceed its narrow gamut.
Sadly monitors have the capabilities to be wide gamut but the overwhelming majority aren't. Simple reason is that crap colour management in operating systems means that monitors with wide gamuts look wrong and don't sell very well. I love wide gamut monitors, but some people just can't use them.

Quote:
Originally Posted by naskies View Post
Adobe ... becoming obsolete because consumer equipment is starting to exceed its gamut. For example, monitors that advertise "97% of Adobe RGB" gamut usually also substantially exceed Adobe RGB in some parts of the spectrum.
The only displays which I know of which can display colour significantly outside of AdobeRGB are OLED displays, one single NEC SpectraView display which has been discontinued, and one HP DreamColor model which cost over $5k. My experience is with standard wide gamut display that the primaries graze the edges of AdobeRGB, on the red and blue points, and often fall within the green point. Your interpretation of "well outside" is in my opinion an insignificant improvement. Be delighted to be proven wrong though.

Mind you this is all academic. If you're going to go to the hassle of playing with other colour gamuts then you'd be mad not to go straight for the best one, so in that regard you're quite right .

Quote:
Originally Posted by naskies View Post
ProPhoto RGB has a very wide gamut and is also widely used, though interestingly it still can't represent all of the visible colour spectrum. It's used by Adobe CS products internally, so for example in Lightroom if you open a RAW DSLR image (with edits applied) for editing in Photoshop, you'll notice that the default colour space is ProPhoto RGB.
Interestingly some of ProPhotoRGB's colours aren't real. That's how they cover so much of the visible spectrum using only 3 primary points. The blue value of (0,255,0) results in a division by zero if you use the standard textbook methods of converting colour spaces.

Also another note, ProPhotoRGB is not used in Adobe Products internally. They will either all use the working profile of the photo (like Photoshop), or in case of Lightroom there's a profile loosely based on ProPhoto but with a linear gamma curve called MelissaRGB. ProPhotoRGB just happens to be the out of the box default working profile that is applied to images when they leave Lightroom.

Quote:
Originally Posted by naskies View Post
For my own images, I edit in ProPhoto RGB for the whole workflow but convert to JPEG format with sRGB colour space for long term storage. My lifetime collection is already at 94 GB - of only "published" keepers, with no storage of RAWs or multiple sequence shots. It's definitely not ideal, but a smaller set of data is easier to "guarantee" longevity. (I keep my raw data on external drives, but I won't lose sleep if they die.)
Same workflow as mine. Good to see someone of sense rather than those who apply the theory of HDDs are cheap so we keep every crap photo out of the camera.
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  #12  
Old 11-06-2013, 02:26 PM
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Mike,

One important thing that hasn't been mentioned here is selecting the appropriate rendering intent if you use a fully colour managed workflow. This refers to how colours are handled when you move between devices with a wider/narrower gamut. Here's a good primer article on it:

http://www.cambridgeincolour.com/tut...conversion.htm

For vibrant, high contrast, "processed" images such as astro images and landscapes - I prefer saturation intent. For more subtle images with lots of subtle tones in the highlights/lowlights, I like to use perceptual intent.

Usually, the printer will just make the choice for you and you don't have to worry about intents. However, if you want to squeeze every last bit of performance out of the equipment and maximise the oomph of your images, it's good to be aware of intents.

Quote:
Originally Posted by Garbz View Post
Sadly monitors have the capabilities to be wide gamut but the overwhelming majority aren't. Simple reason is that crap colour management in operating systems means that monitors with wide gamuts look wrong and don't sell very well. I love wide gamut monitors, but some people just can't use them.
Yes, it's a shame that support for colour profiles is so poor and/or awkwardly implemented by operating system and consumer software alike. I've noticed that some companies, such as Dell, have resorted to shipping some of their wide gamut monitors in "sRGB mode" by default. Fewer tech support calls to deal with, I suppose...

Quote:
The only displays which I know of which can display colour significantly outside of AdobeRGB are OLED displays, one single NEC SpectraView display which has been discontinued, and one HP DreamColor model which cost over $5k. My experience is with standard wide gamut display that the primaries graze the edges of AdobeRGB, on the red and blue points, and often fall within the green point. Your interpretation of "well outside" is in my opinion an insignificant improvement. Be delighted to be proven wrong though.
Yeah, fair enough. I was referring to a few of the consumer monitors that I've looked at in recent years. For example, the Dell U3011 that I'm using has the green and green primaries outside of AdobeRGB, and blue just within (see link below, I don't have my own 2D plot handy on my computer). Although many consumer monitors advertise "98% Adobe RGB" coverage, they may actually cover say 125% of the visible spectrum that AdobeRGB does.

http://www.tftcentral.co.uk/reviews/...dell_u3011.htm

However, you're right in that you're unlikely to go "wow that's a shade of green that I've never seen on a monitor before" with these consumer monitors.

That said, the saturation of the yellows and golds covered by my printer are very noticeable to the eye - e.g. in a golden sunset, or a portrait taken during the golden hour.

Quote:
Also another note, ProPhotoRGB is not used in Adobe Products internally. They will either all use the working profile of the photo (like Photoshop), or in case of Lightroom there's a profile loosely based on ProPhoto but with a linear gamma curve called MelissaRGB. ProPhotoRGB just happens to be the out of the box default working profile that is applied to images when they leave Lightroom.
Aah, I stand corrected - thanks
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Old 11-06-2013, 04:20 PM
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I've always used Adobe RGB.
If you're getting your stuff printed it will match up with what the print shops use and there's less chance of getting duds.
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Old 14-06-2013, 08:17 AM
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Quote:
Originally Posted by naskies View Post
Mike,

Yes, it's a shame that support for colour profiles is so poor and/or awkwardly implemented by operating system and consumer software alike. I've noticed that some companies, such as Dell, have resorted to shipping some of their wide gamut monitors in "sRGB mode" by default. Fewer tech support calls to deal with, I suppose...
I was coping ok with this thread until that point. I have a great Dell U2410 monitor which I love but had stuck with it in sRGB mode.

If I switch it to Adobe RGB mode, the colours on screen change quite noticeably, particularly when looking at bioluminescence images like this:

http://philhart.com/content/biolumin...nd-lakes-again

The blues change from pale, almost washed out in sRGB to vivid, highly saturated (perhaps too much so) in Adobe RGB.

I can understand that change if I was looking at an Adobe RGB file in Photoshop, where the monitor in sRGB mode couldn't display the gamut but it could in Adobe RGB mode.

But the web images are sRGB so why do they display so much differently between the two modes? It's like the monitor is stretching the sRGB image to make full use of the Adobe RGB gamut, when what I really want is to see those sRGB files the way others would. (This seems like an undesired kind of rendering intent in the monitor, but there doesn't seem to be a setting for that?).

So now if I use the monitor in Adobe RGB mode, I see the pictures differently to what most people would using an sRGB monitor, but if I use the monitor in sRGB mode then I see them (much) differently to somebody using an Adobe RGB monitor. Arghhh..

Phil
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Old 14-06-2013, 09:18 AM
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Are you calibrating the monitor, Phil? You also need to view images with a colour managed application.

Cheers,
Rick.
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Old 14-06-2013, 10:07 AM
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Are you calibrating the monitor, Phil? You also need to view images with a colour managed application.

Cheers,
Rick.
I'm using the monitor presets for sRGB and Adobe RGB. They may not be perfect but I reckon they'll be pretty good for a monitor of this standard. There's something much more fundamental that I still don't have my head around.

I can understand why the image would look different in colour managed Photoshop.. if I view an Adobe RGB image with sRGB monitor setting then naturally enough it must show the image in the reduced colour space. But I don't understand why the images online look so much different when I switch colour spaces on the monitor.. it should be shown within sRGB gamut with both monitor settings? I guess that's where my misunderstanding might be.. the browser is not colour managed at all so the monitor uses its full gamut to display the images even though they are nominally sRGB?
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Old 14-06-2013, 12:20 PM
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I'm using the monitor presets for sRGB and Adobe RGB. They may not be perfect but I reckon they'll be pretty good for a monitor of this standard.
Even high end monitors designed for colour critical work need calibration. The Dell monitor probably has defaults that make it look "good" i.e. bright and flashy.

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Originally Posted by philiphart View Post
I can understand why the image would look different in colour managed Photoshop.. if I view an Adobe RGB image with sRGB monitor setting then naturally enough it must show the image in the reduced colour space. But I don't understand why the images online look so much different when I switch colour spaces on the monitor.. it should be shown within sRGB gamut with both monitor settings? I guess that's where my misunderstanding might be.. the browser is not colour managed at all so the monitor uses its full gamut to display the images even though they are nominally sRGB?
With no colour management the RGB values are just sent directly to the screen to interpret as it sees fit. Say you have an 8-bit colour which is completely green <0,255,0>. On a screen set to sRGB gamut this will give you the maximum green. On a screen set to AdobeRGB gamut it will be the maximum green in that wider gamut, i.e. more saturated.

So, what you are seeing is what I'd expect...

Cheers,
Rick.
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Old 14-06-2013, 12:28 PM
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EDIT (this written before seeing last post)..

Well I guess if I don't tell Windows (and therefore Photoshop) that I've changed the monitor settings, then the image has to look different. I can see in Photoshop color settings that the Monitor Profile is sRGB (determined by advanced settings under Windows Control Panel-Display-Color Settings). So I will leave the monitor on its sRGB factory setting (and one day calibrate to that) unless I change the Control Panel settings to match..
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Old 14-06-2013, 12:43 PM
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To me there is no point doing image processing work of any kind if your monitor isn't calibrated. Calibration tools are cheap as chips now.
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Old 14-06-2013, 01:28 PM
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To me there is no point doing image processing work of any kind if your monitor isn't calibrated. Calibration tools are cheap as chips now.
I think there is no point doing image processing if you have not calibrated your monitor to ensure you have good tonal range across the bright and dark end of the range. But you can do that quite effectively using calibration charts.

At least for me, with a *quality* monitor, having adjusted brightness settings, it's easy to see that my colours are ok. My Dell U2410 (which I love) has stupid 'warm' and 'cool' settings, but the sRGB setting is clearly giving a good result. I look at my images on loads of monitors, projectors, prints etc all over the place.. and within their various limitations they look fine. Of course there are plenty of cheaper monitors that have colour bias that are much harder to work with.

It's just at the extreme end of the gamut (eg bioluminescence) where things start getting tricky in terms of how that looks to somebody viewing in colour managed applications on a wider gamut monitor. I'm getting my head around it more.. and I've ordered a big book on the topic .
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