Author Topic: color management ON looks worse. What profile do you use when it's OFF?  (Read 15454 times)

Offline dennis

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A few questions for you:

What Nikon camera model are you using?  The newer Nikon cameras let you choose sRGB or Adobe RGB separate from any "look".  The older models you had to choose a certain look to get AdobeRGB.  I suggest you shoot in AdobeRGB whatever that takes.

What version of Photo Mechanic are you using?  If you don't have Photoshop installed and are using an older version of Photo Mechanic, there were known issues with PM not properly color managing AdobeRGB files (specifically, unless the AdobeRGB or Nikon Adobe RGB profile was embedded into a JPEG then PM would use an badly formatted AdobeRGB profile which essentially caused the color management system to do no color matching, just like if CM was turned off in PM).

I would set Capture NX to use AdobeRGB as the working space.  Then just save your JPEGs or TIFFs with the AdobeRGB profile embedded.  Then make sure you turn color management ON in PM.  If all your monitors are properly calibrated, then the images should look very close on the different computers.

Regarding extracting JPEGs from NEF: on the older camera models there may be an issue (can't recall) where the NEF is marked as "AdobeRGB" but the preview is really in sRGB color space.  If this is the case, you would want to embed the sRGB profile by hand into the extracted JPEG files.  If you are shooting RAW+JPEG mode then if all is working correctly the extracted JPEG should look (color-wise) like the JPEG that came out of the camera.

If you need to convert to sRGB (e.g. for web pages or email) then do that conversion on the fly using the option in PM (saveas, export, etc).  Keep your working files in the larger gamut AdobeRGB space.

Hope this helps...

--dennis

Offline rjp

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A few questions for you:

What Nikon camera model are you using?  The newer Nikon cameras let you choose sRGB or Adobe RGB separate from any "look".  The older models you had to choose a certain look to get AdobeRGB.  I suggest you shoot in AdobeRGB whatever that takes.

What version of Photo Mechanic are you using?  If you don't have Photoshop installed and are using an older version of Photo Mechanic, there were known issues with PM not properly color managing AdobeRGB files (specifically, unless the AdobeRGB or Nikon Adobe RGB profile was embedded into a JPEG then PM would use an badly formatted AdobeRGB profile which essentially caused the color management system to do no color matching, just like if CM was turned off in PM).

I would set Capture NX to use AdobeRGB as the working space.  Then just save your JPEGs or TIFFs with the AdobeRGB profile embedded.  Then make sure you turn color management ON in PM.  If all your monitors are properly calibrated, then the images should look very close on the different computers.

Regarding extracting JPEGs from NEF: on the older camera models there may be an issue (can't recall) where the NEF is marked as "AdobeRGB" but the preview is really in sRGB color space.  If this is the case, you would want to embed the sRGB profile by hand into the extracted JPEG files.  If you are shooting RAW+JPEG mode then if all is working correctly the extracted JPEG should look (color-wise) like the JPEG that came out of the camera.

If you need to convert to sRGB (e.g. for web pages or email) then do that conversion on the fly using the option in PM (saveas, export, etc).  Keep your working files in the larger gamut AdobeRGB space.

Hope this helps...

--dennis

Hi Dennis,

I would prefer to work in sRGB throughout the entire process from start to finish for now. I understand it is a smaller gamut than Adobe (aRGB). I only mentioned aRGB previously as part of a test I performed to help understand what is happening.

I am using a Nikon D40. I am shooting RAW only.

I am using color mode 3a which is sRGB. Since I am saving as NEFs from NX2 I assume this only effects the embedded JPEG.

I am using the latest beta version of PM for the mac (4.6.1 beta 7).

My mac is running OS X Leopard.


« Last Edit: May 05, 2009, 12:57:10 PM by rjp »

Offline dennis

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Hi Dennis,

I would prefer to work in sRGB throughout the entire process from start to finish for now. I understand it is a smaller gamut than Adobe (aRGB). I only mentioned aRGB previously as part of a test I performed to help understand what is happening.

I am using a Nikon D40. I am shooting RAW only.

I am using color mode 3a which is sRGB. Since I am saving as NEFs from NX2 I assume this only effects the embedded JPEG.

I am using the latest beta version of PM for the mac (4.6.1 beta 7).

My mac is running OS X Leopard.

OK, stick with sRGB if you want.  If everything is working OK then you may not even be able to tell the difference between an image in sRGB space and one in AdobeRGB space other than the saturated reds might be a bit duller in the sRGB version.

PS - if you extract a JPEG from the RAW file but don't include any Exif information AND don't include an embedded profile, then PM doesn't know what the profile for the photo is and will call it undefined.  If PM thinks it is undefined, then PM sends the pixels straight to the display without matching (since it doesn't know what to match FROM) as if you had CM OFF.  So you should either include the Exif info (which contains a tag identifying as sRGB) or embed the profile (sRGB) when you extract JPEGs (the latter is the safest).  Also, if you are always using sRGB in PM, then you can tell PM to use sRGB when the profile is undefined (see the color management preferences).  In this case, a JPEG that is extracted without Exif or a profile will be assumed to be sRGB and with PM's CM ON it will match from sRGB to the monitor's color space.

If you change your monitor color profile then of course the screen will change if the profile is different (e.g. a different gamma).  If you have two different profiles, A & B, then presumably only one of them is "correct" in the sense of how you want to view the photos.  If A is correct and chosen, then PM matches to A's color space and the system draws this appropriately.  If B is chosen, then PM matches to B's color space and the system draws this as before but the results will be different (e.g. different gamma).

If you turn PM's CM OFF then PM doesn't match the photo's color space to the monitor profile, it just copies the pixels to the screen buffer.

The only reasons to turn PM's CM OFF is for a slight speed advantage or if you are doing something like screen grabs and you want to assign a more reasonable color space (e.g. sRGB) to the pixels captured by the screen grab (by default, a screen capture is in the color space of your monitor profile which typically is a smaller gamut than either sRGB or AdobeRGB unless you have a really nice monitor).

--dennis


Offline rjp

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Hi Dennis,

I would prefer to work in sRGB throughout the entire process from start to finish for now. I understand it is a smaller gamut than Adobe (aRGB). I only mentioned aRGB previously as part of a test I performed to help understand what is happening.

I am using a Nikon D40. I am shooting RAW only.

I am using color mode 3a which is sRGB. Since I am saving as NEFs from NX2 I assume this only effects the embedded JPEG.

I am using the latest beta version of PM for the mac (4.6.1 beta 7).

My mac is running OS X Leopard.

If you turn PM's CM OFF then PM doesn't match the photo's color space to the monitor profile, it just copies the pixels to the screen buffer.


--dennis



Dennis,

I do not see this happening.

When I change my monitor profile I see the image on the screen change, and this is true whether PM CM is on or off.

So if the choice of monitor profile is effecting the displayed image, how is it that PM is not using the monitor profile?

Thanks,
Rich

Offline rjp

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Hi Dennis,

I would prefer to work in sRGB throughout the entire process from start to finish for now. I understand it is a smaller gamut than Adobe (aRGB). I only mentioned aRGB previously as part of a test I performed to help understand what is happening.

I am using a Nikon D40. I am shooting RAW only.

I am using color mode 3a which is sRGB. Since I am saving as NEFs from NX2 I assume this only effects the embedded JPEG.

I am using the latest beta version of PM for the mac (4.6.1 beta 7).

My mac is running OS X Leopard.

... PS - if you extract a JPEG from the RAW file but don't include any Exif information AND don't include an embedded profile, then PM doesn't know what the profile for the photo is and will call it undefined.  

--dennis



Dennis,

In this test I was selecting "Preserve Exif data where possible". Only the "Embed ICC profile" option was unselected. So even with EXIF save enabled I still got an undefined colorspace in the extracted JPEGs.

Is it possible that the sRGB colorspace tag is somehow not included in the EXIF data? How could I verify this? I do see "Nikon sRGB 4.0.0.3001 (Embedded)" displayed in both the info tooltips and the {ICC} variable for the original NEF in PM before I extract the JPEGs.

Does this mean it is in the EXIF data? If so then why does it not get extracted with the JPEG?

PS. All of these questions are so I can better understand how PM is working. I never intend to turn CM off. I just want to make sure it's working properly and also that I understand what it is doing. Thanks for your help here.

Offline rjp

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Request for a simple test by someone
« Reply #20 on: May 06, 2009, 03:23:36 PM »
Could somebody please try this simple test?

Please ingest a NEF file with sRGB colorspace into PM and tell me if you see the colors look much more vibrant when PM color management is off compared to on.

Just a simple glance at the contact sheet should suffice. It should be real obvious.

This would help me to know if what I am experiencing is normal.

Thanks.

PS. I am running on a mac with OS X Leopard, and this may be significant. The NEF file is from a D40, Color mode iiia (sRGB).

Offline dennis

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If you turn PM's CM OFF then PM doesn't match the photo's color space to the monitor profile, it just copies the pixels to the screen buffer.

Dennis,

I do not see this happening.

When I change my monitor profile I see the image on the screen change, and this is true whether PM CM is on or off.

So if the choice of monitor profile is effecting the displayed image, how is it that PM is not using the monitor profile?

Thanks,
Rich

When you change your monitor profile (don't know why this is necessary) then everything on the screen changes, right?  Why would you expect PM to look the same if you change your monitor profile?

Also, PM caches the color managed image (and the unmanaged image if necessary), so if you change your monitor profile in the middle of running PM, then you may get unexpected results (i.e. PM will push pixels that have been managed with the old monitor profile).  You may want to make sure you are flushing your image cache when you quit PM!!!

Do you have Photoshop installed?  If you don't, you can probably use Preview instead.  To demonstrate that PM is working correctly, turn ON the CM for PM and open a photo side by side in PM and Photoshop/Preview.  They should look the same.

If you turn OFF the CM in PM then the results are unpredictable.  Maybe they "look" better with CM off, but for accurate viewing results (assuming you have the correct monitor profile selected) you want to turn on CM.

--dennis

Offline dennis

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... PS - if you extract a JPEG from the RAW file but don't include any Exif information AND don't include an embedded profile, then PM doesn't know what the profile for the photo is and will call it undefined.  

Dennis,

In this test I was selecting "Preserve Exif data where possible". Only the "Embed ICC profile" option was unselected. So even with EXIF save enabled I still got an undefined colorspace in the extracted JPEGs.

Is it possible that the sRGB colorspace tag is somehow not included in the EXIF data? How could I verify this? I do see "Nikon sRGB 4.0.0.3001 (Embedded)" displayed in both the info tooltips and the {ICC} variable for the original NEF in PM before I extract the JPEGs.

Does this mean it is in the EXIF data? If so then why does it not get extracted with the JPEG?

PS. All of these questions are so I can better understand how PM is working. I never intend to turn CM off. I just want to make sure it's working properly and also that I understand what it is doing. Thanks for your help here.


It is possible that the Exif from the extracted JPEG doesn't have the Exif ICC color space tag, but that would be a bug.  Maybe you can send me an extracted JPEG for me to look at (where the source NEF says "Nikon sRGB 4.0.0.3001 (Embedded)")?

Best way to deal with this is to embed the profile in the extracted JPEG.  Maybe you can send me both JPEGs (with/without embedded profile)?  If these are too large, please contact me privately and I can send you an FTP upload link.

--dennis


Offline rjp

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If you turn PM's CM OFF then PM doesn't match the photo's color space to the monitor profile, it just copies the pixels to the screen buffer.

Dennis,

I do not see this happening.

When I change my monitor profile I see the image on the screen change, and this is true whether PM CM is on or off.

So if the choice of monitor profile is effecting the displayed image, how is it that PM is not using the monitor profile?

Thanks,
Rich

When you change your monitor profile (don't know why this is necessary) then everything on the screen changes, right?  Why would you expect PM to look the same if you change your monitor profile?


Dennis,
I didn't expect it to look the same. I was replying to your comment in which I thought you were telling it me it would. Since this differed from my observations I was just asking for clarification.

I'm referring to the following statement you made, which gave me the impression that the monitor profile was ignored. Perhaps I missunderstood.
"If you turn PM's CM OFF then PM doesn't match the photo's color space to the monitor profile, it just copies the pixels to the screen buffer."

Regarding the issue of why I'm changing the monitor profile, it's just part of my tests to try to understand how PM is handling sRGB color management. I want to understand why it seems to treat aRGB differently than sRGB. It's just out of curiosity for my interest in this hobby, that's all. Of course I typically only use one good monitor profile in normal use.
 
« Last Edit: May 06, 2009, 08:58:23 PM by rjp »

Offline rjp

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... PS - if you extract a JPEG from the RAW file but don't include any Exif information AND don't include an embedded profile, then PM doesn't know what the profile for the photo is and will call it undefined.  

Dennis,

In this test I was selecting "Preserve Exif data where possible". Only the "Embed ICC profile" option was unselected. So even with EXIF save enabled I still got an undefined colorspace in the extracted JPEGs.

Is it possible that the sRGB colorspace tag is somehow not included in the EXIF data? How could I verify this? I do see "Nikon sRGB 4.0.0.3001 (Embedded)" displayed in both the info tooltips and the {ICC} variable for the original NEF in PM before I extract the JPEGs.

Does this mean it is in the EXIF data? If so then why does it not get extracted with the JPEG?

PS. All of these questions are so I can better understand how PM is working. I never intend to turn CM off. I just want to make sure it's working properly and also that I understand what it is doing. Thanks for your help here.


It is possible that the Exif from the extracted JPEG doesn't have the Exif ICC color space tag, but that would be a bug.  Maybe you can send me an extracted JPEG for me to look at (where the source NEF says "Nikon sRGB 4.0.0.3001 (Embedded)")?

Best way to deal with this is to embed the profile in the extracted JPEG.  Maybe you can send me both JPEGs (with/without embedded profile)?  If these are too large, please contact me privately and I can send you an FTP upload link.

--dennis



I will remember to always choose to embed the profile in the extracted JPEGs from now on. And as for your investigation into the tag by EXIF issue I would be happy to send you two images to demonstrate this.

btw, I just did another test in which in NX2 I saved the same NEF file once as Nikon sRGB, once as sRGB IEC, and once as aRGB. In all cases using "convert" not "assign" of course.

Then I ingested all three NEFS into PM. All three showed up with their {ICC} variables indicating the proper color spaces (embedded). I then extracted JPEGS from all three without selecting the option to embed ICC profile in the extract window. (Testing the EXIF path here)

I then inspected these three JPEGS and found that the one in the Adobe RGB space was properly identified as aRGB, but both the sRGB files had their color space set to undefined.

This fact coupled with the observed differences in how aRGB and sRGB react to CM deactivation makes me think there may be an issue with PM's handling of the sRGB profile in some NEF files.
« Last Edit: May 06, 2009, 09:36:53 PM by rjp »

Offline dennis

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Rich,

OK I think I know what is happening.  There are several different issues here so please bare with me.

1) The sRGB profile that Apple provides in their OS is different than the standard (IEC61966-2.1) sRGB profile.  This has to do with how the profile is defined and implemented.  If I tried to discuss this in detail then you would first need to read Bruce Fraser's books on color management.  Lets just say that if you take the same pixels and use the "Nikon sRGB" profile (which is an approximation of the standard sRGB profile) instead of Apple's sRGB profile then you will get slightly different results, mostly with how the gamma is handled.  These are close but noticeably different (Apple's looks a bit more saturated).

2) If you turn OFF color management in PM then we send the pixels straight to the OS, period.  Same is true if PM thinks the color space is "undefined".  Just because this may look "better" (it certainly give a more punchy red dress) doesn't mean its more accurate.  Theoretically Nikon's sRGB image should be "correct" and if you compare the Nikon NEF in PM and Capture NX they look identical as expected (assuming PM has CM turned ON).  This should be your "reference".

3) Unfortunately Capture NX does not write an Exif color space tag when rewriting a NEF file.  This is OK I suppose (since as I've said before a RAW file doesn't really have a color profile, just its preview).  But when PM extracts the JPEG preview and tries to preserve Exif tags, there is no color space tag to preserve and this is why you end up with an "undefined" profile.  When you go to view this "undefined" profile image, if your PM preference for undetermined is "No default profile" then this is the same as turning CM OFF.  If your PM preference is "sRGB Profile" then you will get Apple's sRGB profile from the system.  If your PM preference is "sRGB IEC61966-2.1" then you should get the same results as with "Nikon sRGB 4.0.0.3001".

I will see about adding a default Exif color space tag in the case where the source (e.g. Capture NX NEF) doesn't have this tag.  In the meantime, I would set your default profile in PM to either "sRGB Profile" or "sRGB IEC61966-2.1" depending on what you think is more accurate (the Apple profile is more up-to-date technology-wise).

Hopefully this answers all of your questions and I can get back to getting a 4.6.1 release out the door.

--dennis

Offline rjp

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Thanks for looking into this Dennis. The bottom line is that PM color management works; that is, when it is on, all the images appear identical even if they are represented in different color spaces internally. That's good news. The extraction I still have some concern about, but it seems that as long as I always choose to embed upon extract everything works out fine.

Yes, I do want you to get back to 4.6.1, but I also know from reading this forum of your constant pursuit of higher quality. I am impressed that you guys are always open to addressing issues identified in the field, and hopefully user feedback like this is helpful. For me personally, I am totally fine with using the PM/NX combination as is since I know now how to work around this issue. The comments below just sum up my final ramblings on this subject after so much experimentation. Perhaps some of them will be useful for future improvements.

You say NX does not write an EXIF color space tag when writing a NEF file, but JPEG extract works perfectly for aRGB NEFS, so this explaination is not entirely consistent. It could be that NX only writes the EXIF tag if the color space differs from it's default (sRGB in this case). The important thing to determine here is which application is behaving inconsistently. Since you are familiar with PM's code you are in the unique position to say whether or not PM is doing the right thing. If so, then perhaps the fault lies with NX.

If I understand your explanation correctly, you are saying that NX embeds the sRGB profile, but does not write a corresponding profile tag to the EXIF data. And this is why when I open a NEF in PM I see it labeled as sRGB (embedded), but when I save it without the  ICC embed option I get a JPEG with undefined colorspace. So you are saying that the PM variable {ICC} is populated based on the embedded profile? I was thinking it was based on the EXIF data.

I thought the embedded profile was already part of the embedded JPEG. When PM saves without the "embed ICC profile" option does it actually remove this existing profile? If so, wouldn't the option be more appropriately named "remove embedded profile" since the NOP route is to leave it as is?

I'm not sure adding a default EXIF color space tag would be a good thing. Assigning color spaces by default is dangerous, and in my opinion should be hard for a user to do accidentally since it could easily do more harm than good. It might be better to just have a warning message if both the EXIF tag and the profile are missing to say that the JPEG will have no color space, proceed (y/n)?

Even better. Would you suppose the embedded profile to be the ultimate definition of color space? If so, why not add code to write an EXIF color space tag to match the embedded profile if the tag is found to be missing or inconsistent with the profile?

Just food for thought.

Rich


« Last Edit: May 09, 2009, 05:37:15 AM by rjp »