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  #1  
Old December 7th, 2017, 04:39 PM
Ted Cousins Ted Cousins is offline
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Default "DNG profile" what is it?

On another Forum, someone has uses the phrase ".dng profile" which, to me, implies that a ".dng" file is not a "digital negative" but is somehow an alternative to a ".icc", "icm" or a ".dcp".

To make it worse, I just read on an x-Rite page how their Color Passport app can output a "DNG profile" (notice the caps and no leading period).

All a bit confusing, any simple clarification available?

Thanks for looking!
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  #2  
Old December 7th, 2017, 05:32 PM
Doug Kerr Doug Kerr is online now
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Hi, Ted,

Quote:
Originally Posted by Ted Cousins View Post
On another Forum, someone has uses the phrase ".dng profile" which, to me, implies that a ".dng" file is not a "digital negative" but is somehow an alternative to a ".icc", "icm" or a ".dcp".

To make it worse, I just read on an x-Rite page how their Color Passport app can output a "DNG profile" (notice the caps and no leading period).

All a bit confusing, any simple clarification available?
I don't know nearly as much about this as I would like to, but as I understand it a DNG profile is a collection of data characterizing the camera (I guess from a colorimetric basis) that is used somehow in connection with the DNG format. As I understand it, this profile can be embedded in a DNG file (*.DNG) proper or can be held in a separate *.DCP file.

I suspect that the locution ".dng profie" is ill-advised.

I guess I should try and learn more about this.

Best regards,

Doug
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  #3  
Old December 7th, 2017, 05:50 PM
Doug Kerr Doug Kerr is online now
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Hi, Ted,

There is some useful information (from a certain perspective) here:

https://rawpedia.rawtherapee.com/How...color_profiles

More later.

Best regards,

Doug
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  #4  
Old December 7th, 2017, 07:24 PM
Doug Kerr Doug Kerr is online now
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Hi, Ted,

It is interesting to note that the DNG specification itself (at least as of version 1.4.0.0, June, 2012, the latest version I have, and perhaps the latest one that exists) makes no mention of a separate file to carry a DNG profile.

So I am not sure where that file format is defined.

Best regards,

Doug
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  #5  
Old December 7th, 2017, 09:53 PM
Asher Kelman Asher Kelman is offline
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The profile is a correction curve that one gets from taking a picture in a particular light with a selected lens and camera using a version of the Gretag Macbeth color card that is included in a handy plastic snap open case.

The Xrite software works only with the RAW file from your camera converted to DNG. The pattern of the color chart is automatically recognized and the adjustment curve is generated so that when applied in a RAW processor, it corrects the color cast of lighting outside of "neutral" 5,000 degree Kelvin daylight. (I think that's the reference).

In Photoshop Adobe Camera Raw I choose the appropriate camera-lens profile for that shoot and any color cast will be removed. (This "Passport" tool doesn't make any chromatic aberration, distortion or vignetting corrections).

I think I have it right. Anyone else is welcome to correct any omissions or errors.

Asher
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  #6  
Old December 8th, 2017, 07:19 AM
Ted Cousins Ted Cousins is offline
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Quote:
Originally Posted by Doug Kerr View Post
Hi, Ted,

I don't know nearly as much about this as I would like to, but as I understand it a DNG profile is a collection of data characterizing the camera (I guess from a colorimetric basis) that is used somehow in connection with the DNG format. As I understand it, this profile can be embedded in a DNG file (*.DNG) proper or can be held in a separate *.DCP file.

I suspect that the locution ".dng profie" is ill-advised.
Agreed, Doug.

And that too was my understanding, so thanks for that.

I've been snapping at the heels of a Moderator lately and didn't want to get it wrong.

best,

Ted
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  #7  
Old December 8th, 2017, 07:31 AM
Ted Cousins Ted Cousins is offline
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Quote:
Originally Posted by Asher Kelman View Post
The profile is a correction curve that one gets from taking a picture in a particular light with a selected lens and camera using a version of the Gretag Macbeth color card that is included in a handy plastic snap open case.

The Xrite software works only with the RAW file from your camera converted to DNG. The pattern of the color chart is automatically recognized and the adjustment curve is generated so that when applied in a RAW processor, it corrects the color cast of lighting outside of "neutral" 5,000 degree Kelvin daylight. (I think that's the reference).

In Photoshop Adobe Camera Raw I choose the appropriate camera-lens profile for that shoot and any color cast will be removed. (This "Passport" tool doesn't make any chromatic aberration, distortion or vignetting corrections).
My title was probably confusing, Asher. Wasn't looking for "Profiles 101", but thanks for the effort, anyway. My only concern was the actual phrase and it looks like a so-called ".dng profile", with the leading period, doesn't exist.

Being perhaps an odd man out, I don't have X-rite software, only an old 'mini-card, and don't use Adobe at all.

RawTherapee is my main editor.

Asher
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  #8  
Old December 8th, 2017, 07:36 AM
Ted Cousins Ted Cousins is offline
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Quote:
Originally Posted by Doug Kerr View Post
Hi, Ted,

There is some useful information (from a certain perspective) here:

https://rawpedia.rawtherapee.com/How...color_profiles

More later.

Best regards,

Doug
Thanks Doug, in the past I've occasionally used Adobe's raw-DNG converter then their DNG editor which could do the same thing. But they stopped supporting Sigma about 10 years ago, so that was that.

later,

Ted
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  #9  
Old December 8th, 2017, 09:19 AM
Ted Cousins Ted Cousins is offline
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So I went back to where someone used ".dcp profile", complained, and got this response:

"Writing .dcp file would be technically correct but, when I have used that term in the past, no one understood what I was on about. The moment I said ".dng profile", people knew."

I guess that makes it OK, eh?

It's a funny world, this photography!

Ted
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  #10  
Old December 8th, 2017, 11:21 AM
Doug Kerr Doug Kerr is online now
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Hi, Ted,

Quote:
Originally Posted by Ted Cousins View Post
So I went back to where someone used ".dcp profile", complained, and got this response:

"Writing .dcp file would be technically correct but, when I have used that term in the past, no one understood what I was on about. The moment I said ".dng profile", people knew."

I guess that makes it OK, eh?
It's perfectly all right to call bison "buffalo" until the buffalo you ordered from Exotics R Us arrives at your zoo.

Best regards,

Doug
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  #11  
Old December 9th, 2017, 02:39 AM
Ted Cousins Ted Cousins is offline
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Quote:
Originally Posted by Doug Kerr View Post
Hi, Ted,

It's perfectly all right to call bison "buffalo" until the buffalo you ordered from Exotics R Us arrives at your zoo.

Best regards,

Doug
Excellent!

Ted
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