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Author Topic: arbitrary RGB profiles for opening RAW  (Read 15446 times)
Schewe
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« Reply #20 on: April 02, 2014, 07:07:53 PM »
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I have printed from a Pro Photo 16 bit tiff  test target directly 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.

Again, in the ICC profile>profile exchange, the originating profile hands off the profile colors to the interchange color specification (prolly CIE XYZ but could be Lab), the CMM (Color Management Module) takes the CIE XYZ numbers and crunches those numbers into the destination profile color space using a rendering intent. Most matrix based (color spaces) only have a single RelCol rendering, v4 profiles with a perceptual will be able to use perceptual. Output color spaces such as you would find with printer profiles prolly have all 4 of the standard rendering intents; Relative Colorimetric, Perceptual, Saturation and Absolute Colorimetric.

So, if you were transforming from PP RGB to your output profile using a perceptual rendering, you got a perceptual rendering.
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Redcrown
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« Reply #21 on: April 02, 2014, 10:51:13 PM »
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Lundberg,

Check your PM here in Lula for help in getting the "jc1" profiles.
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Schewe
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« Reply #22 on: April 02, 2014, 11:32:06 PM »
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Sorry...got nothing...
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Lundberg02
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« Reply #23 on: April 03, 2014, 12:35:17 AM »
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Redcrown, if you would please also send the jc1 to Jeff Schewe. Possibly they could be made available to all forum members?
 
I sent my Pro Photo test target to my Epson via Photoshop manages colors using the appropriate Epson profile and the correct paper setting in the second Print Settings dialog. The test target I think was the Pro Photo jpg from the Colour Collective.
Not sure a jpg is a fair test, but I have a  tiff somewhere also, and I may have used that.
 So,  Schewe says that printing will produce perceptual  because the printer profile has the requisite matrix, but converting from Pro Photo to aRGB  doesn't. I read that this is due to the PP being matrix and aRGB being 3x3 whatever that is.
This raises the question why the ICC would develop an sRGB perceptual conversion only for web use, since print would achieve it if set that way. But maybe some commercial  printing systems don't have all four intents.

Doesn't Photoshop do everything in L a b ?  Why would they have a setting for Perceptual if it doesn't actually do it from PP to aRGB. You would think that would be explained somewhere in settings. I suppose that aRGB to sRGB actually does Perceptual and the other three.
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Schewe
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« Reply #24 on: April 03, 2014, 01:30:22 AM »
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Doesn't Photoshop do everything in L a b ?  Why would they have a setting for Perceptual if it doesn't actually do it from PP to aRGB. You would think that would be explained somewhere in settings. I suppose that aRGB to sRGB actually does Perceptual and the other three.

Again, you are failing to understand the fundamental ICC color transforms...(and no, Photoshop switched to CIE XYZ several-many versions ago).

Photoshop (and Adobe in general) has done a disservice to the industry by allowing people to select what are actually, unavailable rendering intents since, well, forever. I don't know why and many of us have complained since, well Photoshop 6, 7 CS, +. To no avail.

And no...ARGB to sRGB won't supply perceptual unless the sRGB has a perceptual rendering intent–which is ONLY available using one of the special sRGB perceptual V4 profiles.

Look bud, you are swimming upstream without a map. You don't know what you don't know. If you want to learn, cool...but what you've "assumed" so far is off base and screwed up.

Go back to the basics...ICC color management starts with an input profile (scanner or camera) which is transformed into a working space (PP RGB, ARGB, sRGB or whatever). You work on the images...if you want to go out to another RGB color space (like the web) you are limited to matrix color space transforms which if you don't have a v4 RGB space (like the V4 sRGB perceptual) means RelCol. If you go to from a "working space" to "output profile" you'll have all 4 of the rendering intents and all 4 will work (to the extent that the profile maker has done their homework).

Look, for the purposes of simplicity, forget about those exotic alternative RGB color spaces. If you are using ACR or LR, use ProPhoto RGB in 16 bit. Once you have that open as your working space, depending on where you want the image to be output to, pick your profile–if you want a perceptual sRGB (for the web), use the sRGB V4 profile. If you are going out to a printer (table based profiles), use the printer profile to soft proof the image and select the best rendering intent for THAT image...

You are making this more complicated that it should be and you lack some basic understanding of what the ICC color management workflow is intended to be.
« Last Edit: April 03, 2014, 01:32:33 AM by Schewe » Logged
digitaldog
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« Reply #25 on: April 03, 2014, 08:59:46 AM »
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Look, for the purposes of simplicity, forget about those exotic alternative RGB color spaces.
My thoughts exactly. Color management has enough rabbit holes and problems that we really don't need to manufacturer more complexity when it's not needed.
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Andrew Rodney
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madmanchan
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« Reply #26 on: April 03, 2014, 11:33:37 AM »
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One of the applications of choosing an arbitrary output ICC profile in the Workflow Options in ACR is for soft proofing.  For example, you can choose a printer profile and turn on soft proofing (and choice of intent).  I do not recommend opening your document into Ps with such a profile, but while working within ACR itself, some may find this useful.
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Lundberg02
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« Reply #27 on: April 03, 2014, 03:07:26 PM »
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It's BECAUSE I don't understand the process that I bring all this up. Due to your explanation and those of others, I'm getting up to speed. Math doesn't frighten me one bit. If I find something that doesn't make much sense, I ask, and I'm not afraid to expose my ignorance. I have never seen this topic this fully discussed anywhere before, and it's nice to know that experts have complained about the false choices in ACR Workflow Options.
I always use Pro Photo 16 bit as a starting point in RAW, of course. I'm happy that you have confirmed that I get what I ask for in the print process through PS and Epson.  I've learned exactly what you said, that I don't know what I don't know , but I'm not really sure where a person can learn how all the transformations are actually done.  I know I never have seen anywhere that PS uses CIE now instead of L a b.  There's still a lot of stuff out there about doing this or that in L a b, is this still valid?
 I'm going to try Iridient as a result of all this, just for drill.
One (possibly) final question: Does PS CS 5.1 use  a v4 sRGB profile? Adobe never tells you any of these things. The question is academic, because I never convert to sRGB and have no need for it as output.
I think you or digital dog could easily do a full chapter on the real story of rendering in your next book and I wish you would. Maybe Chan has a white paper he could reference, too.  His point about soft proofing is something  not mentioned at all in the Photoshop Forum, which has become so dull I rarely go there.
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digitaldog
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« Reply #28 on: April 03, 2014, 03:36:16 PM »
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Does PS CS 5.1 use  a v4 sRGB profile?

Does it, no. Can it (if one's loaded), I'd suspect so. All the profiles Adobe installes for working space's are V2 matrix profiles. You can only get a Colorimetric intent.
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Andrew Rodney
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Schewe
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« Reply #29 on: April 03, 2014, 11:56:38 PM »
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I know I never have seen anywhere that PS uses CIE now instead of L a b.  There's still a lot of stuff out there about doing this or that in L a b, is this still valid?

If you do a color transform in Photoshop the interchange space for the output profile can be either CIE XYZ or Lab...that's controlled by the output profile (many CMYK profiles seem to use Lab while many RGB printers use CIE XYZ).

I don't recall exactly when Photoshop switched to CIE XYZ as the default interchange color space (pending what a profiles dictates) but I think it's been a long time...well before the "Creative Suite". Could have been Photoshop 6 or 7–I have people who I can ask. I'm pretty sure the change occurred about the time that Thomas Knoll did the Adobe CMM for Photoshop transforms.

In terms of where to go to learn this stuff, well, asking here seems to work and you have two authors here answering your question. Andrew is the author of Color Management for Photographers and my book, The Digital Print goes through the ICC color management workflow. Andrew and I learned this stuff at the feet of Bruce Fraser who is sadly not around to ask but we both have color geek friends we can ask when WE don't know something (although those phone calls always comes at a price :~)

If you want to learn, ask questions...you seem to have learned a lot in this thread so hopefully you won't be flailing about trying to use arbitrary color spaces in ACR (unless you want to upgrade to Photoshop CC).
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Lundberg02
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« Reply #30 on: April 04, 2014, 11:10:43 PM »
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From the Adobe spec for aRGB written 2005:

4.3.8 Encoding and decoding ICC PCS Version 4 values
An image in the ICC Profile Connection Space defined in ICC.1:2004 (Profile version 4.2) using the media-relative colorimetric rendering intent shall be encoded in 24-bit Adobe RGB (1998) color image encoding as specified in this section 4.3.8.
4.3.8.1 Encoding PCS Version 4 in 24-bit Adobe RGB (1998)

Also   http://printing.it-enquirer.com/2006/05/24/icc-color-profile-version-4/     says that all Adobe products are now v4 compliant.

So this should mean that you can do all four renderings from Pro Photo to aRGB. Not sure why sRGB would  not also, except that you're saying no, and the ICC offers a profile to do perceptual.

I agree this forum is a good place to learn. I have your Digital Neg and Digital Print books. In fact , a long time ago you and and others were in a chat room with Dan Margulis, there was some sort of contest and you won his book. You already owned it so you sent it to me. You probably don''t remember , but thanks again.
With Rodney and Chan here also, this is an excellent place to ask questions.
The Photoshop forum is dead, Cambridge in Color is full of nut cases, PhotoLine Forum is only concerned with niceties of the software itself.
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Schewe
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« Reply #31 on: April 05, 2014, 12:14:45 AM »
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Also   http://printing.it-enquirer.com/2006/05/24/icc-color-profile-version-4/     says that all Adobe products are now v4 compliant.

So this should mean that you can do all four renderings from Pro Photo to aRGB. Not sure why sRGB would  not also, except that you're saying no, and the ICC offers a profile to do perceptual.

Again, V4 "compliant" doesn't mean the profile will have perceptual rendering...and I know for a fact that none of the RGB profiles (matrix based) that ship with Photoshop are V4 profiles with perceptual rendering intents. V4 "allows" perceptual rendering, it doesn't mean there is a perceptual rendering intent...

And yes, I remember you Lundberg, I never forget a pretty face...
« Last Edit: April 05, 2014, 12:17:59 AM by Schewe » Logged
digitaldog
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« Reply #32 on: April 05, 2014, 09:34:31 AM »
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So this should mean that you can do all four renderings from Pro Photo to aRGB. Not sure why sRGB would  not also, except that you're saying no, and the ICC offers a profile to do perceptual.

The profile has to be built with the (perceptual) table we're talking about and none are (that are installed by Photoshop) and AFAIK, only a few sRGB profiles were built this way (and as I mentioned, at least one or more is wrong in terms of it's white point).

IF you find a working space profile that has the perceptual rendering intent, you'll know as you'll see it do something different when you pick Perceptual versus RelCol. Now will you like or prefer that rendering? Who know.
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Andrew Rodney
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Lundberg02
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« Reply #33 on: April 05, 2014, 10:54:47 PM »
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Shucks, Jeff, I'm blushing, except that it's hard to see because of the egg on my face.
So let's review what we've learned.
You can load arbitrary profiles in Photoshop CC (only). I'm going to ask in the PhotoLine Forum shortly. I know that you can't in ACDSee Pro 3 for Mac, although they said they will add it to their wish list.
In spite of Color Settings, Photoshop only does RelCol unless you load a v4 profile that has the other three.
Printing from ProPhoto files to Epson printers using Photoshop manages colors will offer all the intents.
Iridient may be a good choice for image processing because it offers arbitrary profiles, what about its rendering?.
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Schewe
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« Reply #34 on: April 06, 2014, 12:01:12 AM »
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In spite of Color Settings, Photoshop only does RelCol unless you load a v4 profile that has the other three.

Correct...in terms of color space (matrix based) profiles.

Printing from ProPhoto files to Epson printers using Photoshop manages colors will offer all the intents.

Correct...most all output profiles (V2 & V4) offer at least 3 out of 4 rendering intents; RelCol, Perceptual & Absolute Colorimetric (Absolute Colorimetric is the same as RelCol except with an absolute rendering of white point–use primarily only for cross rendered proofing) . The 4th, Saturation is little used other than biz graphics.
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digitaldog
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« Reply #35 on: April 06, 2014, 09:21:50 AM »
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Iridient may be a good choice for image processing because it offers arbitrary profiles, what about its rendering?.
That's a matter of the profile, not the application. ID will behave like ACR/LR.
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Andrew Rodney
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elied
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« Reply #36 on: April 06, 2014, 10:27:58 AM »
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Throughout this thread what has mystified me is why nobody has mentioned that since its inception Lightroom has been able to export RGB files in any space, as long as you have the profile in your system's Color folder. Equally mystifying is why a feature that LR has had for 7, 8 years is even today not in PSCS.
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Roll over Ed Weston,
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bjanes
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« Reply #37 on: April 06, 2014, 11:28:01 AM »
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Throughout this thread what has mystified me is why nobody has mentioned that since its inception Lightroom has been able to export RGB files in any space, as long as you have the profile in your system's Color folder. Equally mystifying is why a feature that LR has had for 7, 8 years is even today not in PSCS.

I don't understand this post. PS does not have an export function. One can convert to any profile and use save as in any format that you want. Most of us use 16 bit ProPhoto as default, but one can use 8 bit Adobe RGB or Bruce Lindbloom's Beta RGB if file size is a consideration. However, memory and storage are now cheap and 8 bit files don't make much sense except for the web.

Bill
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digitaldog
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« Reply #38 on: April 06, 2014, 11:34:47 AM »
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Throughout this thread what has mystified me is why nobody has mentioned that since its inception Lightroom has been able to export RGB files in any space, as long as you have the profile in your system's Color folder. Equally mystifying is why a feature that LR has had for 7, 8 years is even today not in PSCS.
Since version 5, (1998) Photoshop has had this ability and more. Convert to Profile, Save As command
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Andrew Rodney
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Lundberg02
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« Reply #39 on: April 06, 2014, 11:28:17 PM »
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So is someone going to tell me that Soft Proof in Photoshop doesn't render anything but relative?
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