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Author Topic: Switch from Adobe RGB to ProPhotos RGB?  (Read 2506 times)
hdomke
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« on: November 26, 2005, 05:59:04 PM »
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For years I have used Adobe RGB as my color space.
My main output is Fine Art prints from an Epson 9600 printer. The source of my files is RAW capture using Canon’a 1Ds Mk2.  I am going for optimal quality and don't mind a little extra work.

Recently, after reading Dan's LAB book, most of my files spend some time in LAB to get maximum color variability.

Now, I'm wondering if my imaging has outgrown my colorspace, should I change to a wider gamut color space such as ProPhoto RGB?

My reading in “Real World Photoshop CS2” by Bruce Fraser prompted the question.  He covers this topic on page 167-174.  He writes:
For inkjet printing, however, Adobe RGB (1998) may be on the small side. Figure 5-6 shows Epson Ultrachrome inks... plotted as a solid against Adobe RGB as a wireframe. Adobe RGB clips a huge chunk of the yellow-orange range, a significant chunk of saturated darker greens and blues, and a tiny bit of magenta-red."

"It's the ability to hold color difference that represents detail, rather than the ability to represent ridiculously saturated colors, that drives Bruce to use ProPhoto RGB for all his digital ... work. The fact that it covers the entire gamut of all his output spaces is simply a nice bonus."

Queston: Should I switch to ProPhoto RGB for future work?

Thanks!
Henry F. Domke

www.henrydomke.com
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Henry

Henry Domke Fine Art
www.henrydomke.com
gmitchel
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« Reply #1 on: November 26, 2005, 06:29:11 PM »
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Quote
For years I have used Adobe RGB as my color space.
Queston: Should I switch to ProPhoto RGB for future work?
[a href=\"index.php?act=findpost&pid=52254\"][{POST_SNAPBACK}][/a]

There are advantages and drawbacks to larger colorspaces. I suggest you do some reading and come to your own conclusion.

I'll offer you some anecdotal evidence to consider. I find with Canon DSLRs, especially the Prosumer DSLRs (D30/D60/10D/20D) that highly saturated reds and yellows can appear to be clipped. Especially if you use Expose To The Right.

I say *APPEAR* because those highly saturated reds and yellows will sometimes appear to run to 255 for one or two channels when you use AdobeRGB as your colorspace. Load the same image into ProPhotoRGB and you will likely find those same channels have values clumped up near by 255 but not at 255.

Some will argue passionately about the virtues of one colorspace or the other. Consistency has its virtue. But my own workflow is a hybrid. I use AdobeRGB for nearly all of my images. I resort to ProPhotoRGB when there is an advantage -- like when I have lots of highly saturated colors that appear to clip in smaller colorspaces.

Cheers,

Mitch
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61Dynamic
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« Reply #2 on: November 26, 2005, 10:55:16 PM »
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Recently, after reading Dan's LAB book, most of my files spend some time in LAB to get maximum color variability.

Now, I'm wondering if my imaging has outgrown my colorspace, should I change to a wider gamut color space such as ProPhoto RGB?
[a href=\"index.php?act=findpost&pid=52254\"][{POST_SNAPBACK}][/a]

Lab itself is a huge color space. It in fact is the largest in existence. Even though ProPhoto extends beyond Lab at a couple points it is still overall, smaller.

If you want to go to ProPhoto, then you also will be editing in 16-bit/channel mode. If you try to use ProPhoto in 8-bit/channel mode then you can actually degrade the image as you edit it. The reason for this is that a 8-bit/channel image does not contain enough information to describe all of ProPhoto and you could introduce noise and/or posterizeation.

Ah, you might be thinking to yourself, "Gee Dan, didn't you just say (er, type) that Lab is larger than ProPhoto? If that is the case wouldn't you run into the same issue with Lab as with ProP?" Why yes, yes you would. That is one of the problems with margoulis's theories on large color gamuts and high-bit editing.

I'm sure I opened a can of worms with that one, but so be it. Margolus (wrong spelling I'm sure) is wrong when it comes to those items and is easily disproved.

If you want to edit in ProPhoto (or even Lab) and properly utilize it, then 16-bit/challel images are in your future assuming the larger files and additional system power needed are not an issue. Otherwise AdobeRGB is as large as it is going to get in the 8-bit/channel world without running into unnecessary degradation.

I personally use ProPhoto all the time but your needs may not call for it. What are your needs in editing/printing?
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Mark D Segal
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« Reply #3 on: November 28, 2005, 08:49:44 AM »
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There is sufficient evidence that the new breed of Epson printers has a colour gamut that is shaped differently and in some respects exceeds the boundaries of ARGB98, therefore I use ProPhoto to make sure my files can take full advantage of the printer's capability. I also edit in 16-bit mode. I'm not concerned about whether Dan Margulis is right or wrong about both issues - there is a huge debate about both items in his Colortheory List (Yahoo discussion group) which anyone is free to join. It makes very educational - and sometimes exciting - reading. Lots of passion and insight by intelligent people who have studied all this in great depth. In the final analysis you know best what works for you by experimenting and looking at the results. It can vary from photo to photo, because one does periodically encounter colour gamut compression issues that are more easily handled in ARGB98 than in ProPhoto.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
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