Raw has no color space. And it doesn't matter what you set your camera to (you're shooting Raw).

I dont think that bit is right RGB, 2D colour space?
who said that?

Does a raw file have a color space?

However, note that the rubbish "not a color space because it contains greyscale channels" can not be reasoned from any of these definitions.

Anyway, IMO the raw files have color spaces, namely the respective camera's color space.

Some prominent photographers have taken the rubbish route, including Jeff Schewe and Andrew Rodney

I chose to compare the characteristics of aRGB with the Camera space, noting their similarities.

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

Ok. . .what color space does the Canon 1DsM3 raw file have? What are the camera color's color coordinates?

What are the spectral properties at D65 and tungsten? What are the separation filter properties of the Bayer RGGB photo sites?

When I use DNG Validate to process a raw file without demosaicing...I get a linear grayscale file.

Ok. . .what color space does the Canon 1DsM3 raw file have?

What are the camera color's color coordinates?

What are the spectral properties at D65 and tungsten?

What are the separation filter properties of the Bayer RGGB photo sites?

The raw file has color information that, until somehow represented as color data (either via demosaicing or some other color interpretation) is grayscale values

When I use DNG Validate to process a raw file without demosaicing...I get a linear grayscale file

Mistakes happen, This does not take away anything from their being prominent photographers.

Those similarities are not greater, than the similarities to sRGB, for example.

Anyway, similarity is not a supplement for the definition. Saying "a color space is something like aRGB, but slightly different" does not cut it.

What definition do you take as basis for the discussion about the "color spacebility" of camera sensors?

When I use DNG Validate to process a raw file without demosaicing...I get a linear grayscale file.

However, I'm not so naive as to take his every word as the absolute truth.
There does not seem to be one definition that covers all bases. You have made some good suggestions and perhaps can help supply a working definition.

On 1/18/08 11:09 AM, "RikWalowit@aol.com"  wrote:

<<Does a raw file have a color space?>>

Fundamentally, absolutely YES, but we may not know what that color space is. The image was recorded through a set of camera spectral sensitivities which defines the intrinsic colorimetric characteristics of the image. An simplistic way to think of this (while not purely accurate) is that the image was recorded through a set of "primaries" and these primaries define the color space of the image.

Practically, it makes little difference unless you are interested in accurate scene-referred data. In the context you described, a simple transform is applied to convert from the camera primaries to a new set of primaries (eg CIE or working space) that have more desirable characteristics than the RAW primaries.

Mathematically, of course, you know the foregoing is true. Matrix algebra informs that if the final color image encoding is a "color space" then so must be all of its infinite number of linear transforms (lets ignore the 1 D non-linear transfer functions), including the original RAW encoding.

Eric Walowit
Tahoe

On 1/18/08 9:36 AM, "Thomas Knoll"  wrote:

The fact that a mosaic array is “grayscale” is a red herring in this argument.  An early processing step fills in the missing values, and you have a 3 or 4 channel image as a result.  For most cameras, if you just “assign” a working space RGB profile, you get a recognizable color image as a result, so it certainly seems like a color space.

The camera color space differences from a more common working color space in that it does not have a unique one-to-one transform to and from CIE XYZ space.  This is because the camera has different color filters than the human eye, and thus sees colors differently.  Any translation from camera color space to CIE XYZ space is an approximation because of this.

On 1/18/08 10:20 AM, "Chris Murphy"  wrote:

I think we'd all agree that CIE XYZ, ProPhoto RGB, and sRGB are each a color space. We consider the whole of ProPhoto RGB a color space even though it contains imaginary colors, from a human point of view. And we consider the whole of sRGB a color space even though it contains less than the colors that we humans can see.

A camera has colors it really can capture and encode as unique values compared to others, that are imaginary to us. They don't exist. There are colors we can see, but the camera can't capture that are imaginary to it. So what to do with these captured values that humans can't see? Well they typically get mapped to something, possibly something that another rather different SPD is already mapped to. Two reds that appear the same to us, but have different SPDs, yet the camera sees them as different so it encodes them with two different RGB values. That's fugitive colors. It's nothing new in photography.

So yes a camera (and thus a Raw file) has a color space. The challenge is what to do with the real and "unreal" colors it's encoding. And how to deal with luminance and dynamic range which is still a really big weak area of the ICC workflow. This is not a one size fits all campaign, to get good results. Color appearance models can help us deal with this better, as getting a 1:1 correlation to XYZ is an appropriate starting point prior to color appearance and gamut mapping, but it's not a desirable end result either on-screen or in print.

If we had spectral sensitivities for the camera, that would make the job of mapping to XYZ better and easier, but we'd still have decisions on what to do with the colors the camera encodes, that are imaginary to us.

Chris

One should think of the raw file as a data file. (or interleaved rgb composite)

To call it a grayscale is probably not the most perceptual way to describe it.

I tend to ask other people who I respect as knowing more than I do. So I asked the follow people this morning and here are their replies. This may make you feel better, you seem to wish to prove your point as being correct and I would submit that the language of the past (essentially Grayscale) needs to be altered after asking the questions of these experts. So I should probably thank you for the efforts.

Thanks for the info, Andrew. I certainly respect you more for having published comments by TK and CM that do not entirely agree with your previous statements. I don't know the other fellow, but I assume he is an expert also.

Therefor the conversion with the matrix (actually, with its inverse) is not satisfactory. I think this is the reason, that no matter how hard one calibrates ACR, one can not get all colors right, not even all colors of the small color checker.

And I agree, DPP gives the best RAW convert in color fidelity, sharpening, and shadow detail. Albeit not as flexible as Lightroom or ACR.

The "Essentially Grayscale" comments date back to another respected color geek and in my case, mentor, Bruce Fraser. I believe I quoted him from his book in the previous debated thread. IF Bruce were alive and had he asked the same questions to this group of experts and received the same answers, I suspect he, (as I will from now on),  would use better language than "essentially Grayscale" to describe this aspect of Raw data.

a camera sensor will have different spectral responses from different spectral sources

Hence the difficulties for creating a profile for a digital camera

I'n not convinced a camera has a fixed "color space" either...which is why ya gotta adjust for the white balance of the raw file

how does this help us processing our images better? can we profile better with this knowledge?

Does a raw file have a color space?

The question is, “Does a raw file have a color space?” Some answer no for various reasons.


----snip----

  Thanks to Adobe for providing these excellent CAM -> XYZ matrices!
*/
  { "Canon EOS-1Ds Mark II", 0,
{ 6517,-602,-867,-8180,15926,2378,-1618,1771,7633 } },

Bjanes:

THE ANSWER IS NO. Andrew is correct. At present most Raw files are numbers only, with no clear unambiguous color information. Sadly.

A raw file is the un calibrated image data for a particular scene - sensor referred data - its not colormetric data, it has to be converted to that in the next step.! Via the camera matrix to CIE XYZ.

Now we have color data.

well thats not completely right

a camera does have a 'colour space'- a very big 'colour space'!
The camera 'colour'  space (or to be precise, sensor space) is determined by its spectral response.

its the raw file that doesn't have a 'colour space' as the data is yet to be correctly interpreted

A raw file is the un calibrated image data for a particular scene - sensor referred data - its not colormetric data, it has to be converted to that in the next step.! Via the camera matrix to CIE XYZ.

Bjanes:

I would say, THE ANSWER IS NO. Andrew seems correct. At present most Raw files are numbers only, with no clear unambiguous color information. Sadly.

I need only refer to the below fragments of your own post: That EOS 1Ds2 matrix comes from Adobe. If the Raw was intended as a vehicle for colorimetric information  surely some colorimetric data would be present in the file itself? Absent such "reference" data, why should  the  American  "Adobe  Interpretation" be accorded more credence than the Danish "Phase One Color Interpretation" or the privately held French  "Edmund Ronald Color Interpretation" ? Just because Mr. Coffin has found Adobe the easiest place to liberate a Cam2xyz matrix from ?

Of course, were the camera manufacturer to cooperate and measure the colorimetric characteristics of the camera, eg spectral responses,  and write this data into the Raw file, then the situation would change: A map with a clearly marked scale is a very different object from a map with no scale. Although of course there is just so much information about "color" to be derived from data viewed through the 3 filters in a Bayer array.

Oh, and by the way, I use camera profiling software I have written myself to determine the color of the images I take with my Phase back- I eat my own dogfood. I've had occasion to discuss camera color with quite a few other people and while all these smart guys have some working solution to the Raw color issues, everybody agrees that existing technology gets you only so far.

Now we run full circle. The initial question was, does a Raw have a color space (not does a camera have a color space).

Just when we were getting somewhere....

Chris Murphy: "So yes a camera (and thus a Raw file) has a color space. "

An early processing step fills in the missing values, and you have a 3 or 4 channel image as a result.

So yes a camera (and thus a Raw file) has a color space.

The image was recorded through a set of camera spectral sensitivities which defines the intrinsic colorimetric characteristics of the image. An simplistic way to think of this (while not purely accurate) is that the image was recorded through a set of "primaries" and these primaries define the color space of the image.

In the context you described, a simple transform is applied to convert from the camera primaries to a new set of primaries (eg CIE or working space) that have more desirable characteristics than the RAW primaries.

it certainly seems like a color space.

If the Raw was intended as a vehicle for colorimetric information  surely some colorimetric data would be present in the file itself?

Absent such "reference" data, why should  the  American  "Adobe  Interpretation" be accorded more credence than the Danish "Phase One Color Interpretation" or the privately held French  "Edmund Ronald Color Interpretation" ? Just because Mr. Coffin has found Adobe the easiest place to liberate a Cam2xyz matrix from ?

Of course, were the camera manufacturer to cooperate and measure the colorimetric characteristics of the camera, eg spectral responses,  and write this data into the Raw file, then the situation would change: A map with a clearly marked scale is a very different object from a map with no scale

Characteristic of Raw primaries is the key in my mind

On 1/19/08 10:11 AM, "Jack Holm"  wrote:

I think a couple of things in Eric’s response could be confusing.

- Unless the camera spectral sensitivities are colorimetric, they do not define the intrinsic colorimetric characteristics of an image.

- Also, primaries are for synthesis and can cause some wrong thinking if discussed in relation to analysis.

The second paragraph of Thomas’ response is important.

The short answer to the question is:

Raw image data is in some native camera color space, but it is not a colorimetric color space, and has no single “correct” relationship to colorimetry.

The same thing could be said about film negative densities.

Someone has to make a choice of how to convert values in non-colorimetric color spaces to colorimetric ones. There are better and worse choices, but no single correct conversion (unless the “scene” you are photographing has only three independent colorants, like with film scanning).

A purist might argue that a color space not based on colorimetry is not really a color space because it is not an assignment of numerical values to colors, defining colors as a human sensation. In the standards committees we decided it is useful to be able to talk about non-colorimetric color spaces so we allow them and use “colorimetric color spaces” when appropriate.

Jack

Color, is a perceptual property. So if you can't see it it's not a 
color. Color is not a particular wavelength of light. It is a 
cognitive perception that is the end result of the excitation of 
photoreceptors followed by retinal processing and ending in the 
visual cortex. We define colors based on perceptual experiments.

A coordinate in a "colorspace" outside the spectrum locus is not a 
color. We often refer to these as "imaginary colors" but this is by 
and large also erroneous (you can't map an imaginary color from one 
colorspace to another as the math (and experimental data) for each 
colorspace breaks down outside the spectrum locus.

A purist might argue that a color space not based on colorimetry is not really a color space because it is not an assignment of numerical values to colors, defining colors as a human sensation

Primaries exist only in an orthogonal system. Raw files do not have primaries.

RAW file - just a data file

Both Eric and Jack are members of the ICC and spend a great deal of time in the various committees (both part of the camera committee) trying to define these kinds of terms. What hope do we have here of coming to some agreement in terms???

Yes he does. And a good lawyer could continue to use the above words of Thomas to try to sway the jury, for example:
When is this early process step happening (before or after we have a raw)? If after, then the lawyer could say "well until that step, this Raw hasn't filled in the missing values, there's no color (yet)".

Chris further lumps the camera and the Raw color space issue into one:
We agree a camera has a color space/color mixing function but what about the Raw? He's somewhat unclear here.

The lawyer could even argue that what Eric says here doesn't apply to the Raw data:
All heading us back to the "Essentially Grayscale", somewhat ambiguous original statement about the Raw data itself.

In the end, too many semantics!

OK, so screw it. I'm gonna go back to saying a raw file is NOT yet a rendered color file (it's raw color data) and is essentially grayscale image data (with the pixels representing what the color could be) waiting to be interpreted into color as a result of a demosaicing process. I also still think that the raw file doesn't have "A" color space as the term "color space" is commonly used.

OK, so screw it. I'm gonna go back to saying a raw file is NOT yet a rendered color file

If we need to call in a lawyer, then we are in deep trouble. They know nothing about color theory but are very good at obfuscating and will advance any thesis that the client wants, as long as they get paid. They do not seek truth, but rather results for their client. After all, do you think OJ is innocent?

Once it's demosaiced to RGB it has a colour space, that being Camera RAW colour space for that particular camera.

Thus far, no one has come up with an ironclad definition of a color space, and indeed there probably are many kinds of color space.

Color model: A method of mapping color using a set of defined dimen-
sions. Some scientific color models such as x,y,Y or L*a*b* encompass all
of human vision and have a defined scale such that a particular color will
always have the same set of values. Other color models such as RGB or
CMYK have no standard defined reference or scale. In order to under-
stand a color in these models you must have a color space definition that
provides a scale and reference.

Color space: A color space is a scientifically defined portion of human
vision. A color space may be defined with any color model. The RGB
values R10,G100,B10 have no meaning by themselves other than the
color is mostly some kind of green. By using a color space definition, the
same set of values can be translated into one of the scientific color models,
giving the values exact meaning. Having a set of RGB values associated
with a color space allows for the exact reproduction of the color.

A color space is a color model that has a known reference and scale, in this case primaries (the
ingredients) and scale (specific quantities of these ingredients).