Color Space Question

domromer · Feb 29, 2008

I'm totally confused about color spaces.

At first I never worried about color space, then I'd upload pics to the web and they'd look like crap. So I read the web is srgb so I converted everything to srgb. Which is fine as long as I'm sending things to the web.

Now I needed to start printing things. It seems commercial printers use srgb while inkjets use cmyk.

So what the heck should my color space be? I just read an article in pop photo and they use adobe rgb I didn't hear them mention cmyk at all.

If I put everything to adobe rgb, when do I convert it to srgb before I send it to web? Will I see the colors change is PS when I convert to srgb from adobe rgb? Will I need to make color adjustments when sending things to the web?

Like I said I'm totally confused. Could someone please shed some light on this subject for me.

Helen B · Mar 1, 2008

Most inkjets behave to the outside world as if they are RGB devices (ie they want RGB data), and they are profiled as RGB devices, even though they use CMYK inks. Working in RGB is OK.

I use Adobe RGB (1998) as my working colour space and then convert to sRGB for the web and for the printing services that don't accept Adobe RGB.

sRGB is a smaller (ie it contains fewer colours) colour space than most inkjet printers are capable of.

Best,
Helen

Later:

"If I put everything to adobe rgb, when do I convert it to srgb before I send it to web? Will I see the colors change is PS when I convert to srgb from adobe rgb? Will I need to make color adjustments when sending things to the web?"

I usually do my conversions immediately before doing the output sharpening, so my last two steps are colour space conversion and then sharpening.

You probably won't see the colours change when you do a conversion. You just loose some of the colours that your monitor probably can't display anyway. The colours change if you simply change the colour space without conversion.

Think of it like this: A colour space is very much like a unit of measurement. It's 30 yards (90 ft) between the bases in a baseball park. A yard is about the same as a metre (meter), so if you convert 30 yards to metres the bases will be 27.4 metres apart. 30 yards and 27.4 metres represent the same distance, and a ball park with the bases 27.4 m apart will look the same as one with the bases 30 yds apart.

Now imagine the bases being 30 m apart. All that has happened is that the unit has changed, the value hasn't. Somebody has assigned the unit to be metres instead of yards. The bases are further apart.

You could play around with this in Photoshop. Make a patch of perfectly even colour using the paintbrush, and sample it. Convert the image to another profile and sample again - you should see the numbers change but not the appearance of the colour. Now assign another profile. You should see the number stay the same, but the appearance will change. All this assumes that the colour you made in the first place is within the gamut of your display.

Does that make sense?

Best,
Helen

domromer · Mar 1, 2008

It makes a lot of senses. Thank s Helen. So would it be smart to covert my workflow to adobe rgb then?

ann · Mar 1, 2008

just to add another thought.

you probably won't see much difference on your monitor, but you will when printing unless as helen has already mentioned the vendor only prints in sRGB.

164

molsen · Mar 2, 2008

honestly, almost everyone i talk to about this - pros, amateurs, printers - all recommend shooting in and using sRGB unless you're going to be doing your own printing. it's simpler and you'll get the best results.

in my experience, this is true

Helen B · Mar 3, 2008

molsen said:
honestly, almost everyone i talk to about this - pros, amateurs, printers - all recommend shooting in and using sRGB unless you're going to be doing your own printing. it's simpler and you'll get the best results.

It is definitely simpler, but shooting and working in Adobe RGB then converting to sRGB for output is simple enough. I recommend that digital photographers make an effort to understand and apply appropriate colour management.

If I want the best output I'm not going to use a printer who only uses sRGB. That's throwing colours away. Those of us who shoot film are often better off using even wider gamut colour spaces than Adobe RGB as our working space.

Inkjet printers have a wider gamut than sRGB. There are already many monitors that exceed the gamut of sRGB, and the number is bound to grow. Are you looking to the future?

Here's what West Coast Imaging has to say in the Color Management section:

"
[FONT=Verdana, Arial, Helvetica, sans-serif]I used to use a Lightjet and had to "convert" my files to the Lightjet profile. Do I need to convert to your profile?[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif] No, you do not need to convert your files when printing with us. Our printing software automatically reads your workingspace profile, then converts the data on-the-fly to the appropriate output profile, before sending it to the output device. This lets you keep your files in a wide-gamut workingspace, and easily repurpose them for other applications. The software that powers most Lightjets is not capable of doing this, which is why you had to "convert" your files.[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]What if my file is not tagged with a workingspace?
We recommend using RGB files for the best results. This conversion will most likely cause a change in how the image looks, so it is recommended that you convert to RGB yourself, so you can control the process.[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]RGB files that are not tagged with a working space will be printed as if they were sRGB files. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]... [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]CMYK files will be converted to Ektaspace PS5 and printed as-is. [/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]My digital camera lets me use sRGB or AdobeRGB. Which should I choose?
Most people find that they make better prints when capturing into AdobeRGB."[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]All good advice, as one would expect from WCI.[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]Best,[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]Helen
[/FONT]

ann · Mar 3, 2008

ahmen, helen.

domromer · Mar 3, 2008

Helen B said:
It is definitely simpler, but shooting and working in Adobe RGB then converting to sRGB for output is simple enough. I recommend that digital photographers make an effort to understand and apply appropriate colour management.

If I want the best output I'm not going to use a printer who only uses sRGB. That's throwing colours away. Those of us who shoot film are often better off using even wider gamut colour spaces than Adobe RGB as our working space.

Inkjet printers have a wider gamut than sRGB. There are already many monitors that exceed the gamut of sRGB, and the number is bound to grow. Are you looking to the future?

Here's what West Coast Imaging has to say in the Color Management section:

"
[FONT=Verdana, Arial, Helvetica, sans-serif]I used to use a Lightjet and had to "convert" my files to the Lightjet profile. Do I need to convert to your profile?[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif] No, you do not need to convert your files when printing with us. Our printing software automatically reads your workingspace profile, then converts the data on-the-fly to the appropriate output profile, before sending it to the output device. This lets you keep your files in a wide-gamut workingspace, and easily repurpose them for other applications. The software that powers most Lightjets is not capable of doing this, which is why you had to "convert" your files.[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]What if my file is not tagged with a workingspace?
We recommend using RGB files for the best results. This conversion will most likely cause a change in how the image looks, so it is recommended that you convert to RGB yourself, so you can control the process.[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]RGB files that are not tagged with a working space will be printed as if they were sRGB files. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]... [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]CMYK files will be converted to Ektaspace PS5 and printed as-is. [/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]My digital camera lets me use sRGB or AdobeRGB. Which should I choose?
Most people find that they make better prints when capturing into AdobeRGB."[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]All good advice, as one would expect from WCI.[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif]Best,[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]Helen
[/FONT]

Ok, I set my camera to adobe rgb, then I set cs3 to adobe rgb 1998, the last thing is lightroom. I have 2 choices there. I can do adobe rgb 1998, or pro photo rgb. When I tick pro photo it comes up with a message saying this is the recommend color space for preserving all colors in lightroom.

SO can I mix pro photo rgb with adobe 1998 rgb, or should I keep everything the same at adobe rgb 1998?

Helen B · Mar 4, 2008

domromer said:
Ok, I set my camera to adobe rgb, then I set cs3 to adobe rgb 1998, the last thing is lightroom. I have 2 choices there. I can do adobe rgb 1998, or pro photo rgb. When I tick pro photo it comes up with a message saying this is the recommend color space for preserving all colors in lightroom.

SO can I mix pro photo rgb with adobe 1998 rgb, or should I keep everything the same at adobe rgb 1998?

The choice in Lightroom is for exporting images - the target profile, isn't it? (Has something changed?). Lightroom itself always uses its own space for editing*, then converts for output. Lightroom does its work in a space that has exactly the same gamut as ProPhoto RGB, though it isn't exactly the same as ProPhoto in other ways: it was designed to match the way Raw files represent colour information.

Exporting to a ProPhoto RGB image will, therefore, keep all the colours that were present in the original or generated in Lightroom. It is a very wide colour space, and is only worth using as an output space if you intend to do later processing (for example you are making a master file for later conversion for end-use) or send it to a real high-end printer. Because it is a very large colour space it is safer to use 16 bit colour than 8 bit. Trying to describe it with only 8 bits per channel can be dangerously coarse and lead to colour banding. Lightroom works in 16 bits internally.

Exporting to Adobe RGB may lose some colours, but it is a good all-round colour space.

If you were going to export from Lightroom in ProPhoto, then it would make some sense to set ProPhoto as the working space in Photoshop, but only if you stick to 16 bit colour.

*Lightroom reads the colour space of imported images that are tagged with a colour space, and assumes sRGB for untagged files then converts them to its internal colour space. Raw files have their own particular colour spaces (the native colour space of the sensor) that the raw converter must understand and convert to a standard colour space.

I hope that I have explained this clearly enough.

Best,
Helen

Tasmaster · Mar 4, 2008

So, in very simple words, you are saying:

- Shoot Adobe RGB because it gives you more colours - a wider gamut.

- Convert to sRGB for the web and printing in case you have to print in sRGB.

Which means that you only need Adobe RGB (or any other wide colour space) if you are printing with a printer that supports, right?

Again trying to put it in simple words (correct me if i am wrong here):

Either shoot sRGB, pricess in sRGB, print in sRGB, or shoot Adobe RGB, pricess in Adobe RGB, print in Adobe RGB - the catch here being that your monitor can't display it but the prints will probably look better. If you have a monitor capable of displaying the full Adobe RGB gamut, i guess you are don't need simple word advice anyway

.

Helen B · Mar 4, 2008

Tasmaster said:
So, in very simple words, you are saying:

- Shoot Adobe RGB because it gives you more colours - a wider gamut.

- Convert to sRGB for the web and printing in case you have to print in sRGB.

Which means that you only need Adobe RGB (or any other wide colour space) if you are printing with a printer that supports, right?

...or if you may be printing with a printer that supports Adobe RGB in the future.

Again trying to put it in simple words (correct me if i am wrong here):

Either shoot sRGB, pricess in sRGB, print in sRGB,...

That's fine, if you will never want anything better than sRGB. If you shoot Raw, and process in Lightroom your shooting and working colour spaces are decided for you. You only get to choose your output space.

... or shoot Adobe RGB, pricess in Adobe RGB, print in Adobe RGB - the catch here being that your monitor can't display it but the prints will probably look better.

I generally save the master files in Adobe RGB, then convert them to whatever is appropriate for output. That may be both sRGB for web display and Adobe RGB for sending to a printer (which will then have the printer profile applied).

If you have a monitor capable of displaying the full Adobe RGB gamut, i guess you are don't need simple word advice anyway .

It's not unknown for people to buy digital photographic equipment that has capabilities that exceed their current requirements or knowledge. For example, do Mac users ever need simple advice about colour space, or do they automatically become knowledgable when they buy a Mac?

Very few monitors display the full Adobe RGB gamut but many exceed sRGB and the number is likely to grow as people see the difference for themselves.

Personally I don't see the point in deliberately throwing away some of the capabilities of your camera, unless short-term simplicity is a major priority.

Best,
Helen

Digital Matt · Mar 4, 2008

One thing that has not been pointed out is that Adobe RGB represents more closely the tones that can be printed in CYMK by a 4 color offset printer. If you are intending to have any of your photos printed in brochures, fliers, or CD layouts for instance, Adobe RGB will give a smooth transition to CYMK.

Tasmaster · Mar 4, 2008

Helen B said:
I generally save the master files in Adobe RGB, then convert them to whatever is appropriate for output. That may be both sRGB for web display and Adobe RGB for sending to a printer (which will then have the printer profile applied).

[...]

Personally I don't see the point in deliberately throwing away some of the capabilities of your camera, unless short-term simplicity is a major priority.

The most sensible approach imho - thanks for the in-depth replies.

I still have issues with color profiles in the real world... for example why Firefox renders the same image very different in Adobe RGB than sRGB.

Helen B · Mar 4, 2008

I was thinking about how to demonstrate the difference between a colour-managed browser and an unmanaged browser when I came across this excellent web page:

http://www.gballard.net/psd/go_live_page_profile/embeddedJPEGprofiles.html#

That page does include the statement: "Further, sRGB workflow is the SAFEST COLOR SPACE to work in -- camera-and-scanner CAPTURE to monitor-and-printer PROOFING -- because sRGB closely resembles our monitor color space profile."

Firefox 3 is colour managed, by the way. Firefox 2 isn't.

Best,
Helen