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Author Topic: arbitrary RGB profiles for opening RAW  (Read 11730 times)
Lundberg02
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« on: March 31, 2014, 05:15:59 PM »
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In response to my question in the Adobe Photoshop Forum, Jeff Schewe, the well known guru, replied that in Photoshop CS6 CC you can add arbitrary RGB profiles to the Workflow Options in ACR.  Workflow Options opens when you click on the blue description of the profile you are opening the RAW file with, at the bottom of the ACR window.
Does anyone know any other RAW file converter that has this option? I have just asked ACDSee tech support about this. It is not apparent that they have this capability in the Mac version. I'm haven't looked thoroughly at any of the others I have yet. You would think that draw or converters based on it would be able to do, this such as GIMP or RAWTherapee.
I have a bunch of iccs I'd like to add, like MaxRGB, PhotoGamut, ECI.
I was able to add iccs to Photoshop 5.1 to use for conversion after opening by going to Library/Application Support/Adobe/Color/Profiles, but I don't see even that capability for ACDSee.
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digitaldog
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« Reply #1 on: March 31, 2014, 06:18:56 PM »
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Iridient Developer should work (Mac only). http://www.iridientdigital.com
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Andrew Rodney
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Royce Howland
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« Reply #2 on: March 31, 2014, 07:09:08 PM »
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As far as I can tell, this new feature of ACR is available only when using it within Photoshop CC, not within CS6. But yes, we do now have the ability in the Adobe workflow to convert our RAW files directly into arbitrary colour spaces.

Though I don't use it, I believe Capture One can do this as well:
http://help.phaseone.com/en/CO7/Output/File-formats/Colors-in-Capture-One.aspx
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Royce Howland
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« Reply #3 on: March 31, 2014, 09:59:36 PM »
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Correct, ACR 8.x in Photoshop CC has the new ability to select arbitrary ICC profiles (which is what I'm pretty sure I said on the ACR Forum).
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Lundberg02
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« Reply #4 on: March 31, 2014, 10:41:07 PM »
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I hope this has been helpful to others, and I thank Andrew, Royce, and Jeff for their information. It will take some effort to establish any benefit from using profiles other than Pro Photo.  I'm not even sure where to start except try using the ProPhoto test file I have. It would be essentially the same as an Ektachrome capture I think.  My present  camera only has 20 bit color depth so I don't think a picture containing deep greens would exercise the process well enough.
I hope the experts will look in again and suggest a file to check this out.
The four choices available to non CC users include the legacy ColorMatch that I don't believe anyone now has a use for. You would think that Adobe would include a newer profile such as PhotoGamut, perhaps, as a standard. Any other suggestions?
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Schewe
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« Reply #5 on: March 31, 2014, 11:38:19 PM »
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The four choices available to non CC users include the legacy ColorMatch that I don't believe anyone now has a use for. You would think that Adobe would include a newer profile such as PhotoGamut, perhaps, as a standard. Any other suggestions?

That was then, this is now...ACR 8.x + Photoshop CC allows you to use any ICC profile as the working space. There is zero chance of that change being offered to previous versions of ACR.
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MichaelEzra
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« Reply #6 on: March 31, 2014, 11:41:25 PM »
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Rawtherapee (http://rawtherapee.com free, open source, cross-platform) allows to output converted image in a user-selectable ICC profile.
For reference: http://50.87.144.65/~rt/w/index.php?title=Color_Management
See section "Output Profile".
There are additional uniquely supported options available, such as custom gamma for the output encoding.
« Last Edit: March 31, 2014, 11:46:12 PM by MichaelEzra » Logged

Lundberg02
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« Reply #7 on: April 01, 2014, 12:09:14 AM »
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I agree that the ability to load any profile makes it moot to include a more modern profile as standard.
I have Rawtherapee, although it's awkward to use in my opinion. It has a lot of fans in the free software community. Thanks for the reference.
There's probably a reference RAW file on the web that has the full gamut of some camera. I'll take a look.
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digitaldog
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« Reply #8 on: April 01, 2014, 09:50:04 AM »
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You would think that Adobe would include a newer profile such as PhotoGamut, perhaps, as a standard. Any other suggestions?
Why? The processing color space is ProPhoto RGB primaries, I see as yet, no reason to use anything but that for the master image rendered from that raw converter.

As for ColorMatch RGB, due to the gamma encoding, it's still a valid working space for those targeting to a CMYK halftone process and have to hand of RGB data.
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Andrew Rodney
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Redcrown
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« Reply #9 on: April 01, 2014, 10:58:20 AM »
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I'm confused, would someone explain what this is all about?

What is the benefit of using an arbitrary ICC profile (different than Prophoto) in ACR?

I thought that ACR uses the Melissa/Prophoto colorspace for all internal processing and then converts that result to the profile specified in the Workflow output options. It that not true?

How is that conversion inside ACR different from passing the file to Photoshop as Prophoto and then converting to an arbitrary profile inside Photoshop?
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digitaldog
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« Reply #10 on: April 01, 2014, 11:15:56 AM »
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I thought that ACR uses the Melissa/Prophoto colorspace for all internal processing and then converts that result to the profile specified in the Workflow output options. It that not true?

Melissa RGB is the name of the color space LR/ACR uses for the histogram and RGB values (outside of soft proofing). This is ProPhoto primaries with a sRGB TRC. This is not the color space used for processing! The internal color space has no name, it's using ProPhoto primaries with a 1.0 TRC.
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Andrew Rodney
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Lundberg02
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« Reply #11 on: April 01, 2014, 01:34:16 PM »
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I defer to digitaldog for any of the technical considerations of using the existing conversion, but it is my understanding that no matter what you want for rendering, rendering in ACR from its space to ProPhoto, and in Photoshop from ProPhoto to aRGB or sRGB, is relative colorimetric.  This is  caused by the matrix representation of the space being different from the smaller gamut spaces.
This all began because I wanted to find a way to get perceptual, which I am beginning to believe may not be possible.
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digitaldog
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« Reply #12 on: April 01, 2014, 01:40:53 PM »
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This all began because I wanted to find a way to get perceptual, which I am beginning to believe may not be possible.
The profile would have to be a working space V4 profile using the PRMG to do this. Good luck. Further, it's quite possible that a perceptual intent (which varies based on who wrote it) may produce less-good results depending on a large number of factors.
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Andrew Rodney
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Lundberg02
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« Reply #13 on: April 01, 2014, 01:43:47 PM »
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One of the members of this forum, jc1, who has not posted for about six months, has a website in which he offers a method of for going from ProPhoto to sRGB using perceptual rendering. He provides an intermediate icc profile for going  from the ProPhoto representation to a "jc1", and then a profile for jc1 to sRGB.  The problem is that you can't download his profiles because his site hasn't been updated since 2011 and the links have expired.  I sent a personal message in this forum but there has been no response. Does anyone know what happened to him?
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Lundberg02
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« Reply #14 on: April 01, 2014, 01:56:26 PM »
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I came across the PRMG stuff during the course of this quest, and I am aware that there is some major difference between v2 and v4. Andrew has confirmed my suspicions, and I am also aware that there may not be that much difference between perceptual and relative now, but I wanted to see for myself.   Another faint hope dashed by the complexity of color management.  If "Color Management For Photographers" has a discussion of the state of the art of rendering it would be a must have for me.   There are a lot of parts under the hood you can't get to, just like a new car.
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digitaldog
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« Reply #15 on: April 01, 2014, 01:59:02 PM »
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There are several V4 sRGB profiles (some with incorrect white points) out there on the web so converting from ProPhoto RGB to sRGB this way is possible. No 'intermediate" profile necessary. How useful it is would be another question.
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Andrew Rodney
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Schewe
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« Reply #16 on: April 01, 2014, 02:11:14 PM »
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Andrew has confirmed my suspicions, and I am also aware that there may not be that much difference between perceptual and relative now, but I wanted to see for myself.

You can download V4 ICC profiles for sRGB from the ICC web page. Note, the 'sRGB v4 Appearance (beta)' will work in Photoshop while it won't work in Lightroom because it does not have the correct device tag (there is a corrected profile out there). I've found that you can get a different rendering using Perceptual with that profile and it sometimes can improve the rendering of reds/oranges by perceptually mapping the colors that would be out of gamut from sRGB.

Also note that while one can use alternative color spaces in ACR for PS CC, the need to do so is very specific (converting directly from raw to CMYK for example). But in my experience you won't get much in the way of benefit than just doing a profile conversion from PP RGB to some other color space in Photoshop because the main difference between the internal processing color space and an output color space is really only the different tone mapping. the internal space as Andrew says is PP RGB color coordinates with a linear (1.0) gamma while the output is PP RGB and a 1.8 gamma. So, there's no real impact on color, just tone.
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Lundberg02
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« Reply #17 on: April 02, 2014, 01:24:27 PM »
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Well, what I really wanted was ProPhoto perceptually rendered to Adobe 1998, but there isn't  an ICC PRMG for  that I can see anywhere on the ICC site.
I also can't find much on the possible problems with perceptual rendering. I just intuitively don't like the idea that relative can map two out of gamuts to the same in gamut.
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Schewe
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« Reply #18 on: April 02, 2014, 02:30:37 PM »
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Actually, it's the receiving profile that controls rendering intent, not the original color space. So, you would need an ARGB V4 ICC profile with perceptual, not a PP RGB V4 profile. But, I've never seen an ARGB V4, only sRGB V4 with perceptual. As far as problems with perceptual, well, that depends entirely on how the perceptual mapping was done. RelCol is standard, Perceptual allows secret sauce for the gamut mapping than may or may not be "optimal".
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Lundberg02
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« Reply #19 on: April 02, 2014, 06:21:52 PM »
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It looks like the perceptual rending to aRGB could be done with the jc1 intemediate profile, but the download link from his website has expired and he is nowhere to be found. I found a site which showed how to do it in Win PS, but the links to his downloads were also expired.
I have printed from a Pro Photo 16 bit tiff  test target  with Photoshop manages colors to my Epson six color on matte and was pleased with the results. That path was set to perceptual but I suppose it really wasn't.
« Last Edit: April 03, 2014, 12:13:06 AM by Lundberg02 » Logged
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