Comments on: Adobe RGB vs sRGB vs ProPhoto RGB

By: Rolfsson

Rolfsson — Sun, 26 Jul 2009 14:40:48 +0000

I've had some trouble getting my mind around this concept of colour spaces. But I'm beginning to think it's a lot like a 24 bit version of the old 8 bit indexed colour format. So we seem to have returned to that old piece of technology.

At the same time I'm thinking that widening the colour space must make the distances between shades greater. The classic sRGB model is like a cube with even sides, R, G and B standing for X, Y and Z respectively. In that space the distance between (192, 192, 192) and (192, 192, 193) is 0.8. But if you stretch the outer limits of the box, the inner distances must stretch too, because we are still operating in 8 bits per channel. So the previously mentioned distance can grow to 2 or even 4. That must mean that we lose subtle shades that we had in the sRGB model, mustn't it?

By: Rolfsson

Rolfsson — Sun, 26 Jul 2009 08:40:48 +0000

By: kgarrison

kgarrison — Thu, 28 May 2009 11:52:13 +0000

The easy way is when you use the “Save for web” click on the “convert to sRGB” checkbox.

By: john

john — Thu, 28 May 2009 05:40:10 +0000

so in photoshop how do you convert to sRGB??? form RGB

By: mutuelle

mutuelle — Thu, 30 Apr 2009 17:06:38 +0000

Excellent article, thank you for the infos down here.
In terms of effects, srgb is better.

By: Christina Montemurro

Christina Montemurro — Tue, 28 Apr 2009 00:27:06 +0000

Thanks for this article. What I get from this is that images for web display only should be converted to sRGB, and images that will be used for prints should be in ProPhotoRGB or Adobe RGB? Is that right?

By: Virginia beach photographer

Virginia beach photographer — Sat, 25 Apr 2009 20:41:02 +0000

A good article with good comparisons. I am enjoying your blog- Nate

By: kgarrison

kgarrison — Fri, 24 Apr 2009 19:31:34 +0000

Thats the best way of looking at it. Granted its pretty deep technically and I am trying to understand it the best I can based on what my pals at Adobe are telling me. But yes, thinking of it like highlights being blown is a great analogy.

By: davidredding

davidredding — Fri, 24 Apr 2009 19:28:29 +0000

I think I understand, so it's like blown highlights, if you shoot JPEG those highlights are gone, if you blow then while shooting all that detail is gone. But if you shoot RAW, you can recover some of the detail in those highlight before converting to Jpeg.

By editing in a larger gamat, you can recover some of those colours that would normally be tossed when you render down to a smaller space, did I get that right?

I guess that is where LR really shines, you can tame the colours in there before outputting a file in a smaller space for final touches.

One question, do you know what space the histogram in Lightroom represents? It would be nice to know what is going to be clipped before exporting

By: kgarrison

kgarrison — Fri, 24 Apr 2009 19:12:17 +0000

Yes you will lose data but you have more control over the data you lose. You can see this in Photoshop by changing the display gamut. You dont have any control over the preview in Lightroom yet though.

By: davidredding

davidredding — Fri, 24 Apr 2009 19:09:05 +0000

Rez is rez, although it may not matter when outputting to the web or printing small, rez does help when printing really big and there is a somewhat of a quality boost by capturing 24mp the down sizing to 12 vs just capturing 12.

I can actually see the difference when editing a 16 bit file vs a 8 bit file. You can start to see banding if you push those pixels to far.

But I have never seen the difference between editing in a large gamat then rendering down to a smaller gamat vs just working with the smaller through out the workflow. Whether the colours are clipped before or after editing, they are gone are they not?

I agree that you want to capture the most amount of data for future use, I always suggest shooting RAW, but when you end result is going to be sRGB anyways.....

By: kgarrison

kgarrison — Fri, 24 Apr 2009 18:33:48 +0000

Good points but it kind of like saying we dont need 24 megapixels over 16 megapixels or 14 bit over 8bit. If you are starting in a smaller gamut then you will start clipping color data right from the beginning. If you start with a larger color gamut you have more data to work with to come up with your final image. You dont want any clipping to occur until your last step in the process for best results.

Will you be able to tell a difference in most cases? Probably not, but as system improve, monitors improve, and output devices improve, yes you will.

By: davidredding

davidredding — Fri, 24 Apr 2009 18:25:14 +0000

Good article, but one question I have yet to see an answer to is whether there is a quality difference between editing in a large gamat like ProPhoto and then converting to sRGB as a last step vs just using sRGB all the way through the workflow.

Also, most monitors can't even display aRGB let alone ProPhoto, so when editing you don't even see some colours while editing. Larger gamats are great in theory, but until we have screens and graphics cards that can display them the advantages will remain nothing more then theory.

By: mike

mike — Wed, 22 Apr 2009 23:06:45 +0000

It's like a funnel. If you start at the big end you have lots of choices and you can choose. If you start at the small end (sRGB) you are stuck with your intial choice and cannot make changes later.

Don;t start at the small end if you care about quality.

go here for a complete explanation:
http://www.gballard.net/psd/go_live_page_profil...

By: Gary

Gary — Tue, 21 Apr 2009 19:19:53 +0000

check your workflow settings in Adobe Camera Raw (clickable blue line at bottom of ACR window). It's probably set to Adobe RGB.

By: Sean Phillips

Sean Phillips — Tue, 21 Apr 2009 01:58:17 +0000

Firefox has had color management capability since v3. The only sticky point is that it is turned off by default. You can follow these instructions to turn it on:

http://www.robgalbraith.com/bins/content_page.a...

By: taylor2nd

taylor2nd — Mon, 20 Apr 2009 14:05:28 +0000

was having trouble with this the othe rday. I shoot adobe rgb and sometimes forget to convert srgb.. results not soo cool when that happens.. Srgb if its gonna go on the web for certain. but if i'm printing adobe rgb.. based on what ya'll are saying I should probably give prophoto A try for my next prints.

By: kgarrison

kgarrison — Mon, 20 Apr 2009 14:01:53 +0000

I have not seen this happen myself. Could be that the embedded jpeg preview image is storing the profile, but it shouldnt that I know of.

By: Kristi aka FiberFool

Kristi aka FiberFool — Mon, 20 Apr 2009 13:58:38 +0000

Thank you! In the last couple of months I had been fighting with color shift issues between PS and web. I think you just provided my answer!!

By: Paul R. Giunta

Paul R. Giunta — Mon, 20 Apr 2009 13:53:03 +0000

I shoot in RAW and my camera is set to sRGB (which I know doesn't mater in RAW) and I have the Color Space in CS4 set to sRGB. Why does CS4 tell me that the profiles do not match? I bring the files off of the camera onto the Mac via Bridge. Is there something in bridge embedding Adobe RGB?

By: Jason

Jason — Mon, 20 Apr 2009 13:46:15 +0000

Really? I did not know that – see ya learn something new every day, thanks Kerry!

By: kgarrison

kgarrison — Mon, 20 Apr 2009 12:36:17 +0000

The in-camera settings for colorspace are only applied if you are shooting in JPEG. If you are shooting in RAW then it is not converted into a particular color space until you bring it into an editor. With Camera Raw the option is at the bottom of the screen.

By: Jason

Jason — Mon, 20 Apr 2009 12:22:49 +0000

Hey Kerry, interesting post here. Not sure I understand the color space to shoot in being answered with "shoot in raw" because I always thought RAW didn't really deal with color spaces. On my 40D I am shooting in raw but still am able to shoot in either Adobe RGB or sRGB.

Also, a great reference on the ProPhoto color space with really good graphics to illustrate the differences can be found at: http://www.luminous-landscape.com/tutorials/pro...

By: kgarrison

kgarrison — Mon, 20 Apr 2009 11:57:43 +0000

You want use whatever your printer uses, usually Adobe RGB, but check with your printer settings.

By: Joey

Joey — Mon, 20 Apr 2009 05:21:55 +0000

great article. the one thing that you did not discuss is for prints. it sounds like to me that Adobe RGB or ProPhoto would be better for prints to get the most color range, but is this true? this topic applied to prints is really what confuses me.

By: Luis Barcelo

Luis Barcelo — Mon, 20 Apr 2009 05:14:27 +0000

Tks for this article, now this thing of color space is more clear to me.