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Color management: Adobe RGB / sRGB explanation.

Journal Entry: Sun Jul 31, 2011, 12:36 AM


Hello,

I've just received some questions from a deviant about color management and I think you might be interested in my answers, if you're wondering how these works. This is just the way I do, some people will probably have different opinions on this, but I try to stick to facts.

I know that whenever I post this kind of thing, I get even more questions :) Please, do the search for yourself after reading this, there's a lot of information on the included documentation from Adobe as well as the web. I'm not a FAQ, OK? :)

1. Do you use sRGB / Adobe RGB on your camera color profile?
I shoot RAW, so I don't need to set the profile in the camera (neither color balance). Adobe RGB gives richer tones when you process your image extensively, but I tend to only use it when I need to convert to CMYK and print on professional printers (i.e. for posters for clients). I usually work in sRGB as it is the expected profile for JPEG images that you send to on-line printing companies, as well as monitor-profile (for viewing images on the web)

Two interesting docs:

The theory: www.cambridgeincolour.com/tuto…

And practice: (old article from 2006, might not be super accurate now but sums up pretty well the pitfalls of using Adobe RGB if you don't know how to use it)
www.kenrockwell.com/tech/adobe…

The second link summarizes it pretty well: "Adobe RGB squeezes colors into a smaller range (makes them duller) before recording them to your file. Special smart software is then needed to expand the colors back to where they should be when opening the file."

I've just done this test for you: I've opened the same RAW file with Adobe RGB and sRGB. Both images display exactly the same on my screen. If I compare R, G, B values for similar pixels, they are of course different, proving that each model renders them differently.  Now, if I work on the image (I've done a simple series of adjustments), I can see a difference in the way extreme colors are rendered. This is explained by the different spaces. As long as you don't heavily retouch, differences are almost nonexistent. Theoretically, you'll get a wider gammut with Adobe RGB, however if you view it on a sRGB screen, it should be difficult to notice it.

2. What is your color space for photoshop work?
sRGB or Adobe RGB, depending on the needs. If you're speaking of the "Working Color Space", this actually just defines the default space whenever you create new images or when you open images that don't have a profile. When I work for the web, I set it to sRGB and don't bother anymore. My understanding is that the "Working Color Space" doesn't affect your colors. I.e. : if you set it to sRGB, yet open a document in Adobe RGB, then Photoshop will handle this document in Adobe RGB, no matter your "Working Color Space". Quoting the documentation:

"A working space profile acts as the source profile for newly created documents that use the associated color model. For example, if Adobe RGB (1998) is the current RGB working space profile, each new RGB document that you create will use colors within the Adobe RGB (1998) gamut. Working spaces also determine the appearance of colors in untagged documents.

If you open a document embedded with a color profile that doesn't match the working space profile, the application uses a color management policy to determine how to handle the color data. In most cases, the default policy is to preserve the embedded profile."


3. In Photoshop what mode do you retouch? RGB/LAB?
RGB is far easier for me.

4. How you achieve constant color tone for each photo story?
Manual color-balance + photos shot in manual exposure = coherent photos allover a series.

I advise you to read "Photoshop for Photographers" from Martin Evening, or the documentation.

Please note that there is a option for advance conversion between profiles in menu Edit -> Assign profile ... This is the one I use for CMYK conversion.

Cheers

JS



Please do not use any of my photos in your art without my agreement. I spend a lot of time on them and they are NOT stock. Using them in your own manipulations, designs, blogs, etc. is a NO-NO and a violation of copyright.







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:iconspiderio:
spiderio Featured By Owner Jul 31, 2011  Professional Interface Designer
this is so great,
i've been wondering about it all the time
and can't figure it out what the big deal
now after i read your explanation i know the difference
thanks very much
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:iconjsmonzani:
jsmonzani Featured By Owner Aug 1, 2011  Professional Photographer
;) You're welcome!
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:iconpixcellz:
pixcellz Featured By Owner Jul 31, 2011
This explanation has been a great help to me. I have always wondered about the quality of your works.

For achieving consistence color tone for photo-story, I believe staying in a single location and use same kind of lighting also matters?
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:iconjsmonzani:
jsmonzani Featured By Owner Jul 31, 2011  Professional Photographer
Absolutely. If you move around, color changes. Also, artificial light can slightly change even at the same location.
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:iconstefmixo:
stefmixo Featured By Owner Jul 31, 2011  Professional Photographer
:clap: For me it's sRGB all the way as I don't like Photoshop and use it only for few specific plugins. (PaintShopPro for all the rest)
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:iconjsmonzani:
jsmonzani Featured By Owner Jul 31, 2011  Professional Photographer
;)
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:iconmakkistyle:
makkistyle Featured By Owner Jul 31, 2011
nice .. thanks for sharing it with us ..
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:iconjsmonzani:
jsmonzani Featured By Owner Jul 31, 2011  Professional Photographer
You're welcome.
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