New article on color management

Started Apr 26, 2013 | Discussions thread
OP gollywop Veteran Member • Posts: 8,284
Re: Camera-->sRGB versus Camera-->ProPhoto-->sRGB?

Jack Hogan wrote:

Starting from Raw, when you know your final image needs to be in sRGB, does it make more sense to

1) open it and perform PP in a much larger color space like ProPhotoRGB, converting to sRGB at the very end; or
2) open the Raw file directly in sRGB and stay in it throughout?

A few years ago I used to use Melissa D65 as my primary working color space, fine tuning images in that large space only converting to sRGB at the end of the worlflow if needed. Often in these cases the sRGB version required additional fine tuning but at least the original with all my adjustments would be in Melissa D65 for archival purposes and I wouldn't have to revisit it in the future if/when monitors/media improved. Or so went the theory.

It worked well, except when I realized that I was spending a lot of time re-fine tuning most of my keepers because the vast majority of them needed to be turned into sRGB after all. Statistics to the rescue: 90+% of my keepers need to be in sRGB because someone wants a copy via email or because someone wants to make a wallmart print today - only 1 or so a month get the special fine-art treatment, eventually being printed large to perfection.

And I started thinking that if red flowers clipped when going straight to sRGB, they probably still will when ending up in sRGB after ProPhoto: except that in the latter case you'd only realize that you are clipping them at the end of your session, adding additional PP time to get them the way you want them. So I now do it the other way around: sRGB throughout for most keepers and only start in aRGB or a larger space with the very few images that I print large. CNX2, which I use on 100% of my captures (90% of the time ending it there, without needing a trip to CS5), makes it easy to make this change after the fact leaving all other adjustments intact. This thread gave me the impulse to revisit this decision.

Thanks to Tim Lookinbill's Blue Ball, gollywop's sunset and a flower Raw files, all of which have clipped histograms in sRGB that are not clipped in ProPhoto in the areas of interest, I was able to use ACR 6.7 and CS5 to investigate the differences to be expected in 1 and 2 above.

If opened with the neutral camera profile and no adjustments are applied between opening and converting, the images resulting from the two workflows are virtually idistinguishable. Here Tim's blue ball is shown with workflow 2, 1 and just ProPhoto left to right on my calibrated/profiled Dell U2410 monitor run by Win7, which covers 95% of aRGB.

Very slight differences between the two workflows became apparent when adjustments were introduced. Something as simple as changing the ACR 6.7 camera profile from Camera Neutral to Camera Landscape caused some slight but visible differences to appear in the two resulting images, neither necessarily better than the other. Switching back to Camera Neutral and pushing a more aggressive adjustment (CEP3 Tonal Contrast at default settings) resulted in this comparison:

There are tiny localized differences (sRGB only to the left, ProPhoto converted to sRGB to the right). I know where they are, so I can spot them easily. But neither image is clearly more accurate or preferable to the other.

So unless someone has a good argument for otherwise, I think I am going to stick with my current approach: sRGB as my day-to-day working color space, and aRGB/MelissaD65 for the few occasions when I feel it is necessary. As opposed to the other way around.


PS For those who are wondering, ProPhoto/aRGB from start to finish give clearly better colors on my U2410 monitor than the sRGB/ProPhoto+sRGB workflows discussed above. This is especially evident in gollywop's sunset image.

PPS Apologies for cross posting on LuLa, these two threads came about independently and at the same time.

Thanks for that comparison, Jack.

The strategy that you suggest is more or less where I've come down over the years as well, particularly since I've been far more web-oriented in recent times.  I take my web-destined dngs into ACR and process them for optimal (my taste) results in sRGB and make a snapshot (labelled, of course, "sRGB"). This dng becomes my archive.  I then either save a jpeg out of ACR or, more often, take the psd into PS for some further PP, particularly Shadows/Highlights (sometimes), sizing/resampling and output sharpening.  If there is anything particularly arduous or non-obvious about the PP, I create a "settings" text file with a description of what was done. Using the short hand I've developed over the years, these entries are quick and easy and allow very quick and sure replication if needed.

[I've adopted a similar workflow when using RPP now that Andrey has added the possibility to output in sRGB.  That was a nice move.]

If I now want a print-destined version, I simply go back to ACR and revamp things using either Adobe RGB or ProPhotoRGB for the working space.  It rarely takes much change to get an "optimal" production in the broader space (usually just less reduction in Highlights, a touch higher White, and perhaps a little more aggression with Clarity and Vibrance).  I then save this version as another snapshot (yep, you've guessed the name).  The result then goes into PS for appropriate PP.

I find that, for my print-destined PP, relative to the web-destined PP, it helps to pull the center of the curve up just slightly (a couple of points vertically), add a touch more saturation (4-8), and give it some Local Contrast (Hiraloam - but employing an inverted Luminance mask -- I've written an action that does this quite nicely). I then tweak things with a soft proofed duplicate using the printer/paper profile. Then I resize/resample, output sharpen, and print.

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