Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: JRSmit on December 09, 2010, 05:00:46 pm
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I have just returned from a workshop on color management, and in that session the facilitator stated that when shooting in raw the raw result is different depending the colorspace setting on the camera sRGB or ARGB. The facilitator got this info from a dutch Nikon executive. I always believed that this was not the case. I am going to test this myself this weekend, but can anyone shed some light on this?
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Color space setting has absolutely no effect on the raw data. Neither white balance has any effect on the raw data.
It is scary that this comes from a workshop on color management
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Perhaps Nikon stores the assigned color space in metadata, and some RAW processors honor that flag?
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Perhaps Nikon stores the assigned color space in metadata, and some RAW processors honor that flag?
Yes, at least Capture NX / NX2 does that, but the way it was presented is misleading. One of the benefits of shooting RAW is that you can decide later to use or not the metadata
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I have just returned from a workshop on color management, and in that session the facilitator stated that when shooting in raw the raw result is different depending the colorspace setting on the camera sRGB or ARGB.
The facilitator is dead wrong, raw is raw, it has no actual color space at this stage of life and the camera settings have zero effect on this raw data.
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The facilitator is dead wrong, raw is raw, it has no actual color space at this stage of life and the camera settings have zero effect on this raw data.
Andrew, that is what i always understood, so i talked to the facilitator during the break, and she said that this was stated to her by this nikon executive. Now that worried me.
I just did a quick test, using a dummy head with a colorful scarf and some necklace with small minerals on it, in a studio set up, and then processed the raws in LR to see if i could observe differences. Sofar no diff at all. Will try tomorow with some more objects, incl a colorchecker24 card, just to be sure.
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...she said that this was stated to her by this nikon executive. Will try tomorow with some more objects, incl a colorchecker24 card, just to be sure.
Well she and the Nikon exe are wrong <g>. Go ahead a do a test, but you’ll see that what you set on the camera has zero effect on the raw (other than exposure and ISO).
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Yep. The Nikon rep is wrong.
Learned this from another digital guru a couple of years ago. Testing confirms.
FWIW, what I learned is that for the embeded jpeg file (used as a thumbnail on the back of the camera and for unprocessed browsing in say Photo Mechanic), will be affected by the profile, but not the raw (unprocessed) data. You should run the camera in sRGB and tone down the contrast a notch or two so that your preview on the display is more accurate as to the image info, color, saturation, etc. You want to know what that raw image captured!
Using vivid and more vivid may look nice on the back of the camera or as a camera-produced jpeg, but is far from reality of what the raw data contains. It's the same situation on Canon cameras, too.
The images look flat and lifeless on the camera, but once you craft it in ACR in LR and PS, its fine.
By going this route, you insure that your histogram is close and that the file has all the info. It's then up to you to make magic back home on your calibrated system.
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Yep. The Nikon rep is wrong.
Something tells me they aren't wrong, rather, the person giving the clinic didn't understand what they meant. I'm skeptical that anyone who would believe that the color space setting in the camera would have an impact on the RAW data has the required technical knowledge to be giving a seminar on color management. I think it's more likely that she asked a question and misunderstood the answer that was given.
ETA - Then again... based on my recent experience with Canon (yes I know it was Nikon.. the point is that representatives of a company often dispense false information) is any indication I can't say that I'd be all that surprised if they did make such a claim.
Cheers, Joe
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Hi,
The choice of RGB may have a certain effect on the way the in camera histogram is calculated and that also applies to the white balance.
In addition raw conversion software may implement the camera settings. If general purpose raw conversion software is used, like Lightroom, this would certainly not be the case.
Best regards
Erik
I have just returned from a workshop on color management, and in that session the facilitator stated that when shooting in raw the raw result is different depending the colorspace setting on the camera sRGB or ARGB. The facilitator got this info from a dutch Nikon executive. I always believed that this was not the case. I am going to test this myself this weekend, but can anyone shed some light on this?
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Well she and the Nikon exe are wrong <g>. Go ahead a do a test, but you’ll see that what you set on the camera has zero effect on the raw (other than exposure and ISO).
I did the following test: shoot a "very friendly model" with the colrspace setting as the only change, also i shot a colochecker24 again with both settings. (no clipping). I created dcp's from the colorchecher images. Then in LR i white balanced the images, and assigned the profile to one the model images, alternating between profiles did not visibly show a difference, nor did the histogram change. The same for the other model image, switching between the model images did not show a difference at all.
So my conclusion is that indeed setting the colorspace in my camera does not alter the raw.
I attached both model images, be it reduced in pixels:
Will communicate with the facilitator to get her take on this.
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If someone is using picture controls in their Nikon camera then the colour space may have a bearing? I haven't used picture controls for a while but I believe that the recommendation is to set it for Adobe RGB. At the end of the day this is a complete non issue because if it doesn't affect the raw which one you choose then where is the problem? :) ::)
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The facilitator is dead wrong, raw is raw, it has no actual color space at this stage of life and the camera settings have zero effect on this raw data.
I have read that not all raws are created equally and Nikon embeds something in theirs that makes them different? The fact that it is difficult to get a universal converter would back this up. Perhaps someone more knowledgeable than me can confirm this?
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Addendum:
As Larry (Langier) already stated, the camera controls do affect the jpg preview in the nef file. I downloaded a demo of photo-mechanic to view the previews of the model images and indeed they are diferent.
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1. The color space setting does NOT affect the RAW data. This can be confirmed using PhotoBola’s Rawnalyze (Raw Image Analysis) program. As far as RAW is concern, the selected color space is just a tag.
2. A full-sized JPEG-compressed image is stored in the NEF file using the “Basic” quality level. This image is transformed into the selected color space. When viewing a NEF file in ViewNX and most image viewers, it’s the stored JPEG that you see (usually a configurable option in viewers; in ViewNX you get the JPEG until you click the RAW button.) Any image viewer that is color managed will display the JPEG properly.
3. NIKON CAMERA DISPLAY SYSTEMS ARE NOT COLOR MANAGED!
So what does all this mean? If you take two images of the same scene, with different color spaces, the RAW data will be the same, the embedded images will appear exactly the same in ViewNX and in most image viewers, but the review images on the camera will appear different. On the camera’s display, the image stored in Adobe RGB will suffer a color shift. It’s the same loss of saturation and brightness that you get when you view an Adobe RGB image in a non-color managed application, such as IE. Of course, this also causes the histogram to change.
ViewNX can be configured to use the embedded color space or to override the embedded and use the color space selected in the options. Nikon provides 10 different color spaces to choose from.
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At the risk of going off topic I ask how many photographers rely on the camera's display for judging colour? I certainly wouldn't. I use Nikon Cameras. Others may be better?
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At the risk of going off topic I ask how many photographers rely on the camera's display for judging colour? I certainly wouldn't. I use Nikon Cameras. Others may be better?
I don't even use my computer monitor to judge color. I use it to judge saturation and contrast, but for color I perform a custom white balance and simply presume that the colors are right. My eyes are performing white-balance shifts as the lighting changes. Something that looked nice and neutral before I got up to go to the bathroom will have turned bluish by the time I get back. If there's a neutral reference in the scene (or in a shot of a neutral reference) I'll check the RGB values of the reference to ensure they're reading the same. That's how I get around the problem of my eyes changing.
But then again, I'm not a big Photoshopper. A touch of EC, A little local-contrast, sharpening if needed, and maybe a global-contrast adjustment and I'm usually done. So...works for me, but it's not for everyone.
That said, I have to add...that little monitor on my D90 gives a pretty good rendition.
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I don't know what you are doing in the bathroom to turn the monitor bluish? :) :) ;). Seriously if you can't trust your computer monitor how can you trust your camera monitor if it is only about 20% the size of the computer monitor. IMO the computer monitor is for changing colour,saturation and contrast to taste and not looking for an "accurate" rendering of the scene. :)
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Well hell, sometimes it just feels good to step barefoot into it knee deep just to wiggle your toes and feel it moving between them. On my good foot at least.. ;)
I'm going to throw some ideas out there as food for thought.. not as gospel though some will be.
When considering the sRGB vs. Adobe98 question consider this:
It's conventional 'wisdom' that white balance also doesn't change in raw. That we can change the white balance after the capture with virtually no image degradation. I find this to be true 'most' of the time. There are exceptions and allow me to explain why I "think" this happens.
Sensors are analog devices. They capture an analog source (light) and through the process of amplifiers, D/A converters, and other electronic circuits we end up with "raw data" on our flash memory cards.
Analog devices have a design threshold where they perform their best (or capture the most data) when operating inside a certain range. Sometimes different ranges produce different sets of data. The ability to capture data on each side of this median indicates the quality of the device, and is often related to the set range of said device. Some DSLR's (all cameras, but using these as an example) capture X amount of data on each side of this median, others of higher quality (due to better design or higher quality components) capture more.
I'm sure we've all noticed a entry level DSLR such as an older Rebel XT350's raw file could only be adjusted so far on each side of this median without serious degradation, but a better quality more expensive DSLR such as the 1ds Mark II (same era) capturing the same image.. producing a like raw file.. is able to be adjusted far more to each side of the median (use exposure to visualize) before experiencing the same image degradation (think color saturation/noise). Of course a full frame vs. crop sensor enters into this, but I think the quality of the sensor and supporting electronics (amps/filters/D/A converters/etc) matter as well. Maybe more.
When I explain this to students I use the term "fat files" and "skinny files." A 1ds Mark II produces fat files compared to the skinny files of a XT350 Rebel.
Now.. concerning white balance. If we're in AWB and it gets 'close' to the right balance, we won't be seeing any image degradation from correcting WB in post with raw files. But, if the AWB gets it wrong, or you're say adjusted to 1900k and shooting in 8000k.. the difference can be more than 'some' cameras sensor/supporting electronics can make up for. I've confirmed this with tests, and suspect it when it happens by chance by looking at the exfil and other numbers. A 1ds Mark II can correct much further for WB than a XT350. Usually when the capabilities of the camera are exceeded it's limited to just one color channel.. red seems to pop up more often.. and most often its just enough, that when combined with the other two channels within spec.. it's a very small difference. Often the image just doesn't look right and you can't put your finger on why.
I think in the above case we're pushing the boundaries enough.. that it gets pretty technical to explain and would require deeper knowledge than Canon/Nikon/Etc cares to give.. and it happens so infrequently.. that they know it happens.. but choose not to acknowledge it does. So they say it doesn't matter. But if it does happen, and I think it does just by virtue of understanding the electronics involved, there is probably an engineer out there working for them who speaks out once in a while. Or tries to explain the concept to a select set of individuals.
I would guess the sRGB/Adobe98 issues are even more on the fringes.. but it would depend on the individual sensor/supporting electronics involved. Something that 99.5% of the time makes no difference.. but that .5% of the time when the scene/settings/exposure pushes the limits of design.. maybe.
Well.. it's starting to dry and cake around my feet.. so I'll move on.. ::)
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Color space and white balance do not affect raw data, Never, not even 0.0001% of the cases
The sensor samples luminosity levels at each photosite and this is what a raw file is, just the value of luminosity at each photosite.
As a matter of fact, raw data is monochrome, not even color.
Now, as most of the sensors have a bayer filter on top of it, each photosite luminosity is influenced by the colored filter on top of it, the same way B&W film respond when using a colored filter.
Knowing the bayer array, you could then separate the appropriate values according to the colors (RGB)
The way white balance works, it to use a factor to multiply the values of each channel. Ussually the Green is not affected (multiply by 1) and the red and blue values are multiplyed by factors up to 2.8. So it does not matter if your light is 1900K and you set your camera to 8000K. THE RAW DATA WILL NOT BE AFFECTED
Later on the postprocessing (after demosaicing and interpolation) is when the process of converting to a color space occurs, so again, COLOR SPACE DOES NOT AFFECT RAW DATA
As a previous poster mentioned, Photobola Rawnalize is a wonderful tool where all this can be proved beyond any doubt. Unfortunately the author, a former member of this forum, has passed away and the program is not updated anymore.
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The facilitator is dead wrong, raw is raw, it has no actual color space at this stage of life
This statement brings up a previous discussion (http://www.luminous-landscape.com/forum/index.php?topic=22471) on this site, where such luminaries in the digital imaging world as Thomas Knoll opined that the raw file does indeed have a color space. Chapter 6 of the DNG specification (http://www.adobe.com/products/dng/pdfs/dng_spec.pdf) is devoted wholly to the subject of mapping the camera color space to the CIE XYZ space.
To paraphrase Bill Clinton, "It depends on what the meaning of the word 'is' is. If the--if he--if 'is' means is and never has been, that is not--that is one thing. If it means there is none, that was a completely true statement....". In other words, it depends on definition and how that definition is parsed.
Since that thread was argued, Douglas Kerr has published a very illuminating 27 page PDF, Digital camera sensor colorimetry (http://dougkerr.net/pumpkin/articles/Sensor_Colorimetry.pdf). The discussion involves the Luther-Ives criteria, matrix transformations, imaginary primaries, metameric matches, and negative RGB values. Very interesting reading for the technically minded.
The conclusion that the camera does not have a strictly defined color space, but in practice it is often convenient to imagine that it does. Both sides of this argument can claim victory :)
Regards,
Bill
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In any case, the "color space" of the camera would be defined by the colors of the bayer array and those cannot be changed by any setting, since they are a physical property of a component of the camera
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I don't know what you are doing in the bathroom to turn the monitor bluish? :) :) ;).
Well, I won't be getting into details on that one...other than to say that I have a regular light bulb in my bathroom, and its light has more red than the daylight bulb at my desk, as well as my sRGB monitor. Human eyes will start to perform a white-balance shift to counter the red. Whites illuminated by daylight, or displayed on a 6500K monitor, will suffer a momentarily blue shift until the eyes shift again.
Seriously if you can't trust your computer monitor how can you trust your camera monitor if it is only about 20% the size of the computer monitor.
I don't trust it. I was just noting that it looks pretty good. I always try to judge by data, not by perception.
IMO the computer monitor is for changing colour,saturation and contrast to taste and not looking for an "accurate" rendering of the scene. :)
I would think that a person who photographs for documentation purposes might have a different opinion.