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Author Topic: Does a raw file have a color space?  (Read 190926 times)

Schewe

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Does a raw file have a color space?
« Reply #120 on: January 24, 2008, 11:45:17 am »

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A good point, Jeff, but there are differences. TGPhoto's post was completely ad hominem with no supporting logic or facts. Perhaps the intent of my Goebbels comparison escaped you.
[a href=\"index.php?act=findpost&pid=169251\"][{POST_SNAPBACK}][/a]


Uh, even your own inline quote should have alerted you to the fact you should have been responding to TGPhoto, not me dooode. And no, the "Goebbels comparison" didn't escape me...yes, I knew he was in change of the Nazi propaganda machine...but it's interesting to note that with a German last name, you choose a Nazi to compare me to. You're just lucky I'm not Jewish (Andrew is and might find a Nazi comparison rather distasteful–I just find it indicative of your general sleazy approach).

Post 51 says:
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However, if one does use that definition, then a raw file or a digital camera does not have a color space

Post 94 says:
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However, it still can be considered a color space according to a broader definition.

So, which is it Bill...did you or did you not have sex with that woman–Monica Lewinsky?

See, even _YOU_ are going around in circles...
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tgphoto

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Does a raw file have a color space?
« Reply #121 on: January 24, 2008, 12:26:37 pm »

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(as was noted in the DPReview thread).
[a href=\"index.php?act=findpost&pid=169232\"][{POST_SNAPBACK}][/a]

If you are trying to compare LL with DPreview, your logic is fuzzy at best.  I've been a member of both forums for about the same length of time, and the MISinformation which is spewed forth on DPreview as gospel truth is simply amazing.

At this point, I could care less if you think RAW has a color space or not.  Your personal attacks on Jeff and Andrew, coupled with your unwillingness to accept the expert opinions of pioneers such as Thomas who are at the forefront of this technology, makes it very difficult for anyone here to take you seriously.

You made your point, and re-made it several times over.  The forum thinks otherwise.  At what point do you step down off your podium?  Your bull stubborn approach does little to help your cause.

Keep yapping Bill as I am sure we'd all love this thread to go on for another 47 pages with you spewing the same mantra over and over again like a broken record.  Doing so doesn't doesn't mean anyone here is going to change their opinion to suit your personal agenda.

So come on, since I know you can't stand to step down (it's always the smallest dogs that have the loudest barks...coincidence?) why don't you ask the question again....does RAW have a color space?
« Last Edit: January 24, 2008, 12:27:08 pm by tgphoto »
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bjanes

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Does a raw file have a color space?
« Reply #122 on: January 24, 2008, 12:57:39 pm »

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Uh, even your own inline quote should have alerted you to the fact you should have been responding to TGPhoto, not me dooode. And no, the "Goebbels comparison" didn't escape me...yes, I knew he was in change of the Nazi propaganda machine...but it's interesting to note that with a German last name, you choose a Nazi to compare me to. You're just lucky I'm not Jewish (Andrew is and might find a Nazi comparison rather distasteful–I just find it indicative of your general sleazy approach).

Post 51 says:
Post 94 says:
So, which is it Bill...did you or did you not have sex with that woman–Monica Lewinsky?

See, even _YOU_ are going around in circles...
[a href=\"index.php?act=findpost&pid=169264\"][{POST_SNAPBACK}][/a]

Jeff,

As I stated, I will not waste time replying to ad hominem debating techniques other than to denounce the approach. OK, the Goebbels comparison was over the top, and I retract it and offer my apologies. With respect to your final question, that depends on what the meaning of "is" is. With proper qualification, I think that either argument is acceptable, and that is the consensus of the experts who have given their opinions. I find it interesting that you have yet to acknowledge any limitations in your own arguments.

I agree it is time to close down this thread, since both views have been well represented. I would encourage the sysop to mark the thread as read only.
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bjanes

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Does a raw file have a color space?
« Reply #123 on: January 24, 2008, 01:09:29 pm »

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At this point, I could care less if you think RAW has a color space or not.  Your personal attacks on Jeff and Andrew, coupled with your unwillingness to accept the expert opinions of pioneers such as Thomas who are at the forefront of this technology, makes it very difficult for anyone here to take you seriously.

[a href=\"index.php?act=findpost&pid=169276\"][{POST_SNAPBACK}][/a]

Really, I would regard the statements by Thomas Knoll and Chris Murphy as supportive of my viewpoint and nowhere have I refused to accept their opinions. Since you have apparently not taken the time to read this thread and determine what actually was said, I regard your comments as completely irrelevant and misleading.
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tgphoto

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Does a raw file have a color space?
« Reply #124 on: January 24, 2008, 08:03:01 pm »

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I regard your comments as completely irrelevant and misleading.
[a href=\"index.php?act=findpost&pid=169288\"][{POST_SNAPBACK}][/a]

Right back at ya bud!  Keep drinking the water up there in Lake Forest, Billy Boy.  It seems to suit you just fine.

I'll stick with science & research, backed by expert opinion and real world experience.

If you ever do decide to come down from whatever you are on and join reality, be sure and let us know if RAW has a color space.

Cheers!
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Tim Lookingbill

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Does a raw file have a color space?
« Reply #125 on: January 24, 2008, 11:02:29 pm »

Getting back on topic, the screenshots below are my attempt at finding an approximate color space of my Pentax K100D RAW file in the language of CIExyz using Raw Developer's eyeball profile creator. With all the subtle color variances I get between Raw converters it seems interpretation by software should be considered as part of the color space recipe. I can't see how you could separate this.

The images are a representation of these variances. It also shows how easily color errors can be induced if just a smidgeon off the xyz radial axis adjust for each primary and color temp transform which causes me to think that software is far more part of the equation in determining the color space of any digital RAW file rather than the camera's lens/sensor characteristics in how it records spectral reflectance properties of any given scene.  

I used the J.Worthy primaries as a starting point to get the test image to look as I saw it at capture. The variances I got of the different cyan hues in the LuLu doll, the different colors in the limetone brick work, fleshtone and pink bow makes it hard to find the exact color space because I can't tell if it's the software or the scene causing the variances.

Determining the color space of a Raw file seems like an unknowable thing.

[attachment=4875:attachment][attachment=4876:attachment][attachment=4877:attachm
ent][attachment=4878:attachment]
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bjanes

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Does a raw file have a color space?
« Reply #126 on: January 25, 2008, 09:06:28 am »

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Determining the color space of a Raw file seems like an unknowable thing.
[{POST_SNAPBACK}][/a]

That is because the camera space is not colorimetric. See this post for an excellent explanation: [a href=\"http://luminous-landscape.com/forum/index.php?showtopic=22471&view=findpost&p=168050]Post 14[/url].

There are approaches other than a 3x3 matrix transform that can circumvent some of these problems.

Bill
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bjanes

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Does a raw file have a color space?
« Reply #127 on: January 25, 2008, 09:14:58 am »

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I just find it indicative of your general sleazy approach).
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I'm sleazy for pointing out your fuzzy logic (grayscale) and deficient debating style (broken record, ignoring and failing to respond to valid objections to your argument, and out right refusal to accept expert opinion that does not agree with your viewpoint--Knoll, Murphy et al)?

There was a glimmer of sunshine when you acknowledged that Thomas Knoll and Chris Murphy might know more than you to, but on seeing the opinion of a couple of more experts and taking their opinions out of context and ignoring the qualifications they placed on their statements, you reverted to your old broken record tactics.

Using your lexicon, I would call you congenial  .
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Tamlin

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Does a raw file have a color space?
« Reply #128 on: January 25, 2008, 11:02:42 am »

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That is because the camera space is not colorimetric. See this post for an excellent explanation: Post 14.

There are approaches other than a 3x3 matrix transform that can circumvent some of these problems.

Bill
[{POST_SNAPBACK}][/a]

Hi Bill!
I've paid attention to this discussion (and your previous one) about raw files and color space. My understanding for this when it comes to practical use for my firm got fortunately resolved earlier in this thread thanks to some help.

But, I'm still curious about why this is discussed. For a non-expert like me, it seems as following:

You are saying that raw is a cake because you have flour, egg, sugar, salt, baking soda etc.

Digital dog and Schewe says that you need to bake the cake by mixing and cooking before it becomes one and the flavor depends upon what receipt you use. For now you only have the raw materials.

I read this one too, in an attempt to understand the discussion better:
[a href=\"http://www.cambridgeincolour.com/tutorials/RAW-file-format.htm]http://www.cambridgeincolour.com/tutorials...file-format.htm[/url]

Could you explain your point of view a bit easier for us non-experts?

Edit: I understand much of what you say and much seems logical. I think what I have biggest problems understanding, is how to define raw as color space with the absense of scaling. As far as I've read here, you assign a scale afterwards and the raw file doesn't have a predetermined scale before this.

This is where I have a hole in my knowledge. How can a raw file have a color space when its values aren't predetermined upon a standardized scale? It would be easier to understand if raw had a scale like CIE. Even if the camera then didn't have a color space of its own, it would be a % of a color space if being open minded. At least a non-colormetric color space. Same as with screens. XXX% of aRGB, XX% of sRGB etc.

In my logic it just as hard as determin length without any measurement units. I can't see how it works without a defined scale.
« Last Edit: January 25, 2008, 02:05:31 pm by Tamlin »
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Peter_DL

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Does a raw file have a color space?
« Reply #129 on: January 25, 2008, 01:01:53 pm »

Bill,

Hope you don’t mind an unusually open comment as follows:


As we all know: The Raw file is just a “gray moth“ until the #1 Raw converter turns it into a “beautiful butterfly“. A kind of ab initio Genesis of color, close to a religious dogma.

Marketing messages have to be simple!


Hence, it’s easy to conflict with Adobe evangelists. Provocation and escalation are just part of the game to drive you in a corner. The pattern is unchanged since years, through various discussions and accross different forums. Even worse, often enough any third-class cheerleaders feel obliged to fill-in and then you can typically forget about it.

Ignore it. Whenever you quote such nonsense you are repeating it, you’re duplicating the message.  On the other side, many reasonable guys have contributed here (including Andrew’s initial post).  So I just can recommend to focus on this part … and you might find more support than expected, whether explicitly given or in between the lines.

Have a nice weekend.
& Best regards, DPL

--
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bjanes

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Does a raw file have a color space?
« Reply #130 on: January 25, 2008, 01:50:31 pm »

Quote
Bill,

Hope you don’t mind an unusually open comment as follows:
As we all know: The Raw file is just a “gray moth“ until the #1 Raw converter turns it into a “beautiful butterfly“. A kind of ab initio Genesis of color, close to a religious dogma.

Marketing messages have to be simple!
Hence, it’s easy to conflict with Adobe evangelists. Provocation and escalation are just part of the game to drive you in a corner. The pattern is unchanged since years, through various discussions and accross different forums. Even worse, often enough any third-class cheerleaders feel obliged to fill-in and then you can typically forget about it.

Ignore it. Whenever you quote such nonsense you are repeating it, you’re duplicating the message.  On the other side, many reasonable guys have contributed here (including Andrew’s initial post).  So I just can recommend to focus on this part … and you might find more support than expected, whether explicitly given or in between the lines.

Have a nice weekend.
& Best regards, DPL

--
[a href=\"index.php?act=findpost&pid=169531\"][{POST_SNAPBACK}][/a]

Peter,

I appreciate your comments. Misinformation, fuzzy logic, carrying water for the master, and arrogance rub me the wrong way, but your recommendation is sound.

Bill
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bjanes

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Does a raw file have a color space?
« Reply #131 on: January 25, 2008, 03:12:10 pm »

Quote
But, I'm still curious about why this is discussed. For a non-expert like me, it seems as following:

You are saying that raw is a cake because you have flour, egg, sugar, salt, baking soda etc.

Digital dog and Schewe says that you need to bake the cake by mixing and cooking before it becomes one and the flavor depends upon what receipt you use. For now you only have the raw materials.

Could you explain your point of view a bit easier for us non-experts?
[{POST_SNAPBACK}][/a]

Tamlin,

Please do not include me among the experts. I am an amateur photo enthusiast and would like to be considered as an intelligent layman with some background in science and math (my profession is medicine).

A raw file from a Bayer sensor contains the color information in the form of a mosaic, as explained very well by Sean MacHugh (by the way, a chemical engineer) on the Cambridge in color site. It contains all the information captured by the sensor, and should not be considered gray scale or monochrome, because the latter type of file contains only luminance information.

Since the mosaic image contains only one color per pixel, the other two colors are filled in by demosaicing early in the conversion process, and you have a 3 or 4 channel image as a result ([a href=\"http://luminous-landscape.com/forum/index.php?showtopic=22471&view=findpost&p=168050]Thomas Knoll[/url]).

The RGB values in the raw file are determined by the spectral characteristics of the sensor and the light falling on the sensor. An intermediate step in raw processing is to convert these color values to those of the internal working space of the raw converter, usually CIE XYZ or linear ProPhotoRGB in the case of ACR.

As Mr. Knoll explained, a perfect conversion could be obtained if the color filters in the camera had a linear relationship to the response of the human eye. Such a sensor is termed colorimetric. Unfortunately, real world sensors vary somewhat from the ideal and are non-colorimetric. In this case, an exact conversion to the CIE XYZ space can not be made, and only an approximation can be accomplished. For a somewhat technical explanation of these processes, see p. 19 of the Wandell reference which discusses colorimetric and non-colorimetric conversions. According to the methods employed, different raw converters may give different approximations. However, at this stage the recipe is relatively precise.

The next step in the raw conversion is to render the intermediate image into a standard colorimetric working space such as Adobe RGB. This rendering is a complicated process and involves considerable compression of the dynamic range to something than be used by a printer or display device. In addition, out of gamut colors have to be mapped into the working space and saturation may be boosted for a better appearance. Excellent discussions of this process are on the Adobe forum (Krogh and Lang). IMHO, this rendering is where the major variations in the recipe occur, and these variations have little to do with whether or not the sensor is colorimetric.

Quote
Edit: I understand much of what you say and much seems logical. I think what I have biggest problems understanding, is how to define raw as color space with the absense of scaling. As far as I've read here, you assign a scale afterwards and the raw file doesn't have a predetermined scale before this.

This is where I have a hole in my knowledge. How can a raw file have a color space when its values aren't predetermined upon a standardized scale?

In my logic it just as hard as determin length without any measurement units. I can't see how it works without a defined scale.
[{POST_SNAPBACK}][/a]

The scale of the raw file is determined by the characteristics of the sensor, and is often expressed as coefficients for a 3x3 matrix conversion. Unlike as with a standard CIE space, these coefficients are not embedded in the raw file but are implicit, according to what camera is being used. However, for a non-colorimetric sensor, the scale is somewhat ambiguous. This is where the argument as to whether a raw file has a color space or not comes in. Some authorities state that a space must be colorimetric and allow an unambiguous interpretation. According to this definition, a raw file does not have a color space. Other authorities do not require that a color space be colorimetric (including Thomas Knoll and Chris Murphy) and affirm that a raw file does have a color space. It is more important to understand concepts than get hung up on semantics. To me it makes sense in the understanding of the conversion process to regard the raw file as having a color space that can be converted to the intermediate space and then the final working space by standard methods.

References:

[a href=\"http://white.stanford.edu/~brian/psy221/reader/Wandell.Color%20Reproduction.pdf]Wandell[/url]

Krogh

Lang
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Tamlin

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Does a raw file have a color space?
« Reply #132 on: January 25, 2008, 04:45:47 pm »

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Thank you for the time and information you have provided! One thing I've learned from philosophy studies, is that there is not nessesarily only one truth and one truth doesn't make the other false. I find this topic interesting and even though it might not result into a conclution, it will still be a learning process that would be useful. I'll read the information and links you have provided and hopefully be wiser and have a better understanding of the discussion!

Edit: I've started reading now and backtracking a bit. Just so I know I'm on the right track, I'd like to ask (and unfortunately I need to invent a word, so you get what I mean. I'm not native english and don't know the correct word for it):

We are talking about a non-colorimetric color space here, not defined as we are used to by CIE reference space with a standardized scale for all raw file, yes?

And the scale and colorspace referred to here, is an inherited color space (invented, I know, but can't find a word for it). The scale of the colorspace is defined by the spectral characteristics of the sensor and the light falling on the sensor, not a standardized colorspace and this is the reference color space.

So what we do, is to convert the non-colorimetric inherited (from camera) colorspace into a colorimetrical color space as defined by CIE reference space when we convert raw into a picture targeted with our output-referred device?
« Last Edit: January 25, 2008, 05:34:51 pm by Tamlin »
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bjanes

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Does a raw file have a color space?
« Reply #133 on: January 25, 2008, 06:04:26 pm »

Quote
Quote

Thank you for the time and information you have provided! One thing I've learned from philosophy studies, is that there is not nessesarily only one truth and one truth doesn't make the other false. I find this topic interesting and even though it might not result into a conclution, it will still be a learning process that would be useful. I'll read the information and links you have provided and hopefully be wiser and have a better understanding of the discussion!

Edit: I've started reading now and backtracking a bit. Just so I know I'm on the right track, I'd like to ask (and unfortunately I need to invent a word, so you get what I mean. I'm not native english and don't know the correct word for it):

We are talking about a non-colorimetric color space here, not defined as we are used to by CIE reference space with a standardized scale for all raw file, yes?

And the scale and colorspace referred to here, is an inherited color space (invented, I know, but can't find a word for it). The scale of the colorspace is defined by the spectral characteristics of the sensor and the light falling on the sensor, not a standardized colorspace and this is the reference color space.

So what we do, is to convert the non-colorimetric inherited (from camera) colorspace into a colorimetrical color space as defined by CIE reference space when we convert raw into a picture targeted with our output-referred device?
[{POST_SNAPBACK}][/a]

Tamlin,

Your conceptualization more or less similar to mine, but I'm not a color scientist. For us non-experts, I think it is more important to have a general conceptual overview of the process than trying to delve into the details, which are quite complex and likely beyond our grasp as shown reading the Wandell reference.

Finally, we should note that color is a perception by the eye and brain rather than a physical attribute. [a href=\"http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html]Poynton[/url] sums it up in his color FAQ:  "Sir Isaac Newton said, 'Indeed rays, properly expressed, are not coloured.' SPDs exist in the physical world, but colour exists only in the eye and the brain."

It is interesting to note that Dr. Wandell is in the psychology department at Stanford, not the physics or engineering departments.

Bill
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Schewe

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Does a raw file have a color space?
« Reply #134 on: January 25, 2008, 09:32:46 pm »

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I'm sleazy for pointing out your fuzzy logic (grayscale) and deficient debating style (broken record, ignoring and failing to respond to valid objections to your argument, and out right refusal to accept expert opinion that does not agree with your viewpoint--Knoll, Murphy et al)?
[a href=\"index.php?act=findpost&pid=169460\"][{POST_SNAPBACK}][/a]

No...I would call the following ad hominem attacks which YOU seem to decry when aimed at you, but seem perfectly acceptable when coming from YOU...that's what I consider sleazy because you don't seem to have the capacity to understand (nor control) your own outbreaks.

See:

#8
"Some prominent photographers have taken the rubbish route, including Jeff Schewe and Andrew Rodney. "

#52
"He accuses me of arguing about how many angels fit on a pin, but what he seems to be trying to accomplish is having to retract any of his ill-considered statements and reach any common understanding of the scientific principles involved. His broken record method of debate reminds me of that used by Joseph Goebbels. "

#86
"Here is another take on this thread by some pretty knowledgeable people over on the DPReview Nikon D3 forum. There are also some interesting comments on the behavior of some contributers to the current thread."

#92
""He who corrects an arrogant man earns insult; and he who reproves a wicked man incurs opprobrium. Reprove not an arrogant man, let he hate you; reprove a wise man, and he will love you. Instruct a wise man, and he becomes still wiser; teach a just man, and he advances in learning."
-- Proverbs 9:7-9""

#94
"These distinctions seem to escape Jeff, who seems more like a bull in a china shop than a purist. His lack of insight and subtlety astonish me."

#131
"Misinformation, fuzzy logic, carrying water for the master, and arrogance rub me the wrong way, but your recommendation is sound."

#108
"The reason the topic recurs, is that these mafia "experts" keep making the same unqualified and misleading statements. This time around, we had a pretty good discussion that was joined by some true experts."

So, it's ok for YOU to resort to ad hominem debate methodology but it's considered poor form when you are the brunt (or your ad hominem is thrown back at ya)? That's what I think is a sleazy method of behavior. And yes, you did say

"OK, the Goebbels comparison was over the top, and I retract it and offer my apologies."

And if I thought for a New York Minute you were sincere I might consider it, but no, alas, you continue to squeal like a stuck pig claiming innocence while lashing out at every potential opportunity (or so it seems). So, from my point of view, the statement was made, insufficiently (or dishonestly) retracted and you aren't the less bit inclined to show any sort of honest contrition.

Oh, yeah, this whole thread was a sleazy (my opinion) attempt at trying to use the guise of scientific discussion to try to discredit statements by Andrew and myself and I point to these following words as guidance...

"I did not want to engage in another flame war over this topic, and had written you privately concerning this matter. On receiving no reply I made the public post."

So, you posted this whole thread as a thrown gauntlet, right? And you don't see anything sleazy in that?

OK, so, since you are just being you (and I am being me) what do you say if I just ignore you as a user? That way I won't be tempted to respond to you...so now you join two others who I have chosen to ignore on the forums. See ya, bye!
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Jonathan Wienke

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Does a raw file have a color space?
« Reply #135 on: January 26, 2008, 09:41:25 am »

After looking through all of the posts by all of the experts, I see some important distinctions between a RAW file and a standard LAB or ProPhoto RGB image:

1. The color data in the RAW is not as strictly defined. The spectral characteristics of the camera CFA are not included in the RAW data. And even if they were, choosing the best way to handle the mismatches between the CFA response and that of the human eye boils down to a judgment call, and no one method is always superior. The best we can do so far is to make an approximation that works in as many situations as possible, but there is no perfect method yet.

2. The RAW data must have a white balance assigned to it before any color conversion to LAB or a standard RGB editing space can occur. This is another judgment factor, and varying this can change the accuracy of the color conversion dramatically. Even if there is a WB reference in the RAW image, it still falls on the photographer to select the part of the image that constitutes the WB reference, and even then the WB setting will be tweaked to some degree in many cases.

While the RAW data does have color information, there are 2 factors that prevent that color information from being as precisely defined in a RAW file as it is in a LAB or a standard RGB space. And those two factors are significant distinguishing characteristics between a fully defined color space such as LAB or ProPhoto and what one has in a RAW file.
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Iliah

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Does a raw file have a color space?
« Reply #136 on: January 26, 2008, 11:41:52 am »

Dear Jonathan ,

"Colour space" simply does not work for raw data for the purpose of raw conversion, it is not an operative term here. Not only the nature of raw data is very different from what "colorimetric colour space" describes; but there is also an instrumental difference. In colour space we define such operations over the colours (like in colour correction) which leave the resulting colour in the same colour space. Operations over the raw data that leave it in raw state is an oxymoron.

Minor things that may be worth mentioning.

CFA response is not all we need to take into account, silica response is no less important. Sensor changes its response substantially across its surface, and depending on the heat which is also non-uniform across the sensor and other elements in the pipeline. Some cameras include autocalibration to account for that, even changing white balance coefficients that go into metadata; some don't.

In a lot of cases with printers we also have problems with ambiguous colour transforms and need to address them based on our personal preferences - that is, lack of precise definition of colour is not one of the reasons that put raw data so much apart from anything else. Even when converting from a large colour space like Lab to a smaller one, like AdobeRGB, the way we map colours sometimes is not straightforward and may be the case to use softproofing.

There are different ways to demosaic raw data. In some cases we do not apply white balance before demosaicing; in some we apply both white balance and gamma transform - and then go to demosaicing. Demosaicing is not always act over the RGBG data, and some demosaicing algorithms even do not consider the raw data to be RGBG. That is not to mention we have different sensor structures, CMY, RGBW, RGBE, RrGgBbGg etc. Even in traditional sensors responses from G1 and G2 are not always the same, G1 allowing to better approximate luminosity while G2 - colour.
« Last Edit: January 26, 2008, 11:43:20 am by Iliah »
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Jonathan Wienke

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Does a raw file have a color space?
« Reply #137 on: January 26, 2008, 12:00:56 pm »

I agree with your minor points except for one thing:

What happens when one maps colors that fall within the source space but are out-of-gamut in the destination is an entirely separate situation from RAW conversion. When converting a ProPhoto image to sRGB, we know exactly what the source colors are. When converting RAW to ProPhoto, we do not. The colorimetric meaning of the RAW data changes depending on the WB setting chosen, as well as the method used to demosaic and interpolate to RAW RGB, and then convert from the RAW RGB to ProPhoto or whatever. At best, we have an educated guess regarding what the color is supposed to be, often sacrificing technical accuracy for a subjective "looks better" result. When converting from ProPhoto to sRGB, we know exactly what the source colors are, the question is merely how to intentionally alter those colors in the least damaging way so that they fit in the destination space.

If there are no out-of-gamut colors, one can convert back and forth between LAB, sRGB, and ProPhoto, and the only alteration to the color channel values will be due to rounding errors, which can be minimized by performing the calculations in 16-bit mode. Each space has a unique definition for a given color.

This is not true of RAW. For any given color, there are any number of RAW values that could match that color. For example, shooting the same scene in tungsten, fluorescent, direct sunlight, open shade, etc. will result in different RAW values. But with a well-designed RAW converter and a decent WB reference, the ProPhoto conversions of these divergent RAWs will be reasonably similar.
« Last Edit: January 26, 2008, 12:13:02 pm by Jonathan Wienke »
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bjanes

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Does a raw file have a color space?
« Reply #138 on: January 26, 2008, 12:23:33 pm »

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No...I would call the following ad hominem attacks which YOU seem to decry when aimed at you, but seem perfectly acceptable when coming from YOU...that's what I consider sleazy because you don't seem to have the capacity to understand (nor control) your own outbreaks.

See:

#8
"Some prominent photographers have taken the rubbish route, including Jeff Schewe and Andrew Rodney. "
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You do not seem to understand the meaning of ad hominem. Here is the defintion from Dictionary.com:

ad ho·mi·nem    
–adjective
1.   appealing to one's prejudices, emotions, or special interests rather than to one's intellect or reason.
2.   attacking an opponent's character rather than answering his argument.


Rubbish route was used by another poster to describe your faulty logic. It refers to a defect in logic rather than to your person or character and is not ad hominem.

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#52
"He accuses me of arguing about how many angels fit on a pin, but what he seems to be trying to accomplish is having to retract any of his ill-considered statements and reach any common understanding of the scientific principles involved. His broken record method of debate reminds me of that used by Joseph Goebbels. "
[a href=\"index.php?act=findpost&pid=169638\"][{POST_SNAPBACK}][/a]

I have printed out 68 pages of this thread and can't find any significant scientific contribution from Jeff, despite his alleged expert status. All he does is obstruct the discussion. It is impossible to debate with him because he does not respond to counter arguments at all or merely repeats the assertion that was challenged.

[a href=\"http://luminous-landscape.com/forum/index.php?showtopic=22471&view=findpost&p=168039]Post 11[/url] Jeff poses questions in an attempt to prove his point. Both Panopeeper and I post detailed responses. Not a peep out of Jeff.

Post 52 Selective quoting and broken record. Jeff initially acknowledges statements made by Thomas Knoll, Chris Murphy, and Eric Walowit. Then he hears another opinion and without any explanation or qualification, he says "screw it" and goes back to his original position. The broken record method is used mainly to ignore the truth of other arguments and to avoid admitting error. One of the best known practitioners of this style was Joseph Goebbels. That doesn't mean Jeff is a Nazi, but merely that he uses the methods of a person who was very adept at avoiding the the truth and who was not open to reason.

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#86
"Here is another take on this thread by some pretty knowledgeable people over on the DPReview Nikon D3 forum. There are also some interesting comments on the behavior of some contributers to the current thread."

#92
""He who corrects an arrogant man earns insult; and he who reproves a wicked man incurs opprobrium. Reprove not an arrogant man, let he hate you; reprove a wise man, and he will love you. Instruct a wise man, and he becomes still wiser; teach a just man, and he advances in learning."
-- Proverbs 9:7-9""
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Jeff, follow your own advice and look in the mirror.


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OK, so, since you are just being you (and I am being me) what do you say if I just ignore you as a user? That way I won't be tempted to respond to you...so now you join two others who I have chosen to ignore on the forums. See ya, bye!
[a href=\"index.php?act=findpost&pid=169638\"][{POST_SNAPBACK}][/a]

That is fine with me. You have contributed nothing significant to this thread and it is a waste of time to debate with you for the reasons given above.
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Iliah

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Does a raw file have a color space?
« Reply #139 on: January 26, 2008, 12:32:12 pm »

Dear Jonathan,

The point is that ambiguity of the colour transform is not something new and unexpected, and is not the reason to separate raw. The nature of the ambiguity is different, but as it often happens it can be dealt with exactly in the same manner as with real colour spaces. Raw converter is soft proofer, for this matter. All the controls you have there are just for that. In many ways we deal with raw in the same manner as we deal with images untagged with colour space. We chose one that gives acceptable rendition and correct from there.

One more minor point - I do not see why you brought ProPhoto to this. However I leave it to you.
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