Adobe RGB v. ProPhoto in the Real World

[DickKenny]

As a result of some good advice given in answer to my recent post on unsatisfactory B&W results from an Epson R1900, I have had all four of my custom paper/printer profiles remade; this time by a highly recommended service in America. The results are outstanding; and in particular, the B&Ws on all four papers are cast-free and very consistent. So terrific - well worth the faffing around, time and cost.

The process has however raised a query. The printout files from which each profile is built, have to be managed by Photoshop using the Adobe RGB colour space. As it happens, my primary tool is Lightroom, with only occasional forays into CS4. As the 'recommended' default colour space for Lr is ProPhoto, I have preferenced that for CS4 as well. It saves an couple of clicks on transfer. And in my real world I cannot tell the difference between them anyway.

Does it all matter? Should I revert to Adobe RGB in both Lr and Ps to match the space that the profiles were built from? Or can I with impunity continue on my merry way - reflecting my delight with the new profiles?

I'll bet there is someone ready to tell me.

[terrywyse]

Should I revert to Adobe RGB in both Lr and Ps to match the space that the profiles were built from? Or can I with impunity continue on my merry way - reflecting my delight with the new profiles?

I'm not sure how a printer profile can be "tied" to another profile in the way you describe.....the only exception to this would be if this profiling service you mentioned created a *device link* profile, a special type of profile and esoteric enough, at least for general photo printing, that it would surprise me if this were the case. (A device link profile is essentially a "hard-wired" transform between a source and destination profile(s). The profile conversion as well as the rendering intent are "baked in" to a single device link profile).

An easy way to test whether you're forced into using AdobeRGB as a source space is like this (you don't even need to print the image for this test):

* Take an image that's in AdobeRGB colorspace (for this test, you could simply assign AdobeRGB to any old image that has a good range of colors). Save this image, being sure to embed AdobeRGB. Call it "AdobeRGB.tif". Now, convert this image to the printer profile (use relative colorimetric w/o black point compensation). Save this under a different filename, being sure to embed the printer profile. Call it maybe "AdobeRGB_to_PrinterProfile.tif" or whatever.

* Go back and open the AdobeRGB image again and *convert* it to ProPhotoRGB using relative colorimetric w/o black point compensation. Save this image with a new filename ("ProPhotoRGB.tif"), being sure to embed ProPhotoRGB to the image. Now convert this image to the printer profile, again using relative colorimetric w/o BPC. Save this image with the printer profile embedded...call it "ProPhotoRGB_to_PrinterProfile.tif".

* View both of the images that you converted to the printer profile. If they look identical, you should be fine to use any source profile you want. If the profile is indeed tied to AdobeRGB in some way, the image that you converted to ProPhotoRGB and then to the printer profile should look very "dead" or desaturated. The reason is that, in the conversion from AdobeRGB to ProPhotoRGB, the RGB numbers in the file would've been reduced so they were properly "scaled" to maintain the same visual appearance of AdobeRGB in the much larger ProPhoto color space. Make sense? Also, using relative colorimetric w/o BPC during the conversion assures that the colors weren't mucked with in any way during the conversion, preserving the color appearance from AdobeRGB to the larger ProPhotoRGB space. (some pinhead (he sez with a smile) might point out that even if perceptual rendering were used for the conversion, it wouldn't have made any difference since these matrix working spaces only offer relative conversion tables anyway...which is true).  :-)

Just to be sure that this is the case, you could go back to the AdobeRGB image and the converted-to-ProPhotoRGB image and print them using your printer profile (using relative colorimetric again...with a LUT-based printer profile it MATTERS this time). If the images look basically the same, you're good to go. If they look wildly different, then there's something going on with the printer profile they made for you.

Like I said, an output/printer profile should pretty much be indifferent as to what gets used as a source profile, the one exception being device link profiles.

Regards,
Terry Wyse

[PeterAit]

As a result of some good advice given in answer to my recent post on unsatisfactory B&W results from an Epson R1900, I have had all four of my custom paper/printer profiles remade; this time by a highly recommended service in America. The results are outstanding; and in particular, the B&Ws on all four papers are cast-free and very consistent. So terrific - well worth the faffing around, time and cost.

The process has however raised a query. The printout files from which each profile is built, have to be managed by Photoshop using the Adobe RGB colour space. As it happens, my primary tool is Lightroom, with only occasional forays into CS4. As the 'recommended' default colour space for Lr is ProPhoto, I have preferenced that for CS4 as well. It saves an couple of clicks on transfer. And in my real world I cannot tell the difference between them anyway.

Does it all matter? Should I revert to Adobe RGB in both Lr and Ps to match the space that the profiles were built from? Or can I with impunity continue on my merry way - reflecting my delight with the new profiles?

I'll bet there is someone ready to tell me.

Could you tell us the service you are so happy with, and the types of profiles that were not giving you good results? Thanks.

[DickKenny]

[quote name='terrywyse' date='Feb 18 2010, 09:51 AM' post='347827']
I'm not sure how a printer profile can be "tied" to another profile in the way you describe....

Thanks very much for your explanation and confirmation work plan. I suspect the nub of this is in your opening sentence (above). I obviously inferred 'tied' in some way, when what I attempted to describe was the initial stage of the profile building process; wherein one prints two files downloaded from the profile service, prior to submitting them, as the basis for the build. At that stage, the instructions were unambiguous. Use Adobe RGB as the colour space when importing files into CS4, and ensure this same colour space remains in the Printer dialog box. I noted this especially as my CS4 is set to ProPhoto colour space to match that of Lightroom. Clearly, from your explanation, this should have no effect on the the eventual printing process using the new profiles. Nevertheless, I will carry out the comparison you so kindly outlined; and thank you for your reply.

[DickKenny]

Could you tell us the service you are so happy with, and the types of profiles that were not giving you good results? Thanks.

The provider I am so happy with was Eric Chan at http://people.csail.mit.edu/ericchan/photos/profiles.html
Probably best to pass on details of the previous provider. I was pretty happy with what I had from them until I ran into the mountain of getting a decent b/w out of the Epson R1900.

[Czornyj]

The process has however raised a query. The printout files from which each profile is built, have to be managed by Photoshop using the Adobe RGB colour space. As it happens, my primary tool is Lightroom, with only occasional forays into CS4. As the 'recommended' default colour space for Lr is ProPhoto, I have preferenced that for CS4 as well. It saves an couple of clicks on transfer. And in my real world I cannot tell the difference between them anyway.

You can use any editing color space you like, the AdobeRGB trick is only Eric's workaround for profiling target+Snow Leo+Epson driver issue:
http://www.luminous-landscape.com/tutorials/solving.shtml

[Wayne Fox]

At that stage, the instructions were unambiguous. Use Adobe RGB as the colour space when importing files into CS4, and ensure this same colour space remains in the Printer dialog box.

Are you printing the targets with Leopard or Snow Leopard?  This sounds very much like the current work around when printing profile targets from those operating systems.  Normally you just print targets with all color management off.

If so, it was their choice to instruct you to use AdobeRGB - probably trying to provide a bullet proof instruction to all.  considering some users may not have or even be aware of ProPhotoRGB they opted to instruct the use of AdobeRGB.  The key is you have to set the exact same profile in both locations ... basically pass a null profile so the operating system will leave the data alone instead of trying to manage it with colorsync.  So you could have used ProPhotoRGB instead and gotten the same results.  

If you aren't on OS X 10.5 or 10.6, then the instructions should have been to disable all color management ... no profiles should have been involved.

[DickKenny]

To all who responded:

Thank you very much for your interest and help. All perfectly clear.

Cordially,

dk