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Color Space Choices for Nikon 5000 Scans

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  #21  
Old 07-30-2010, 06:33 PM
kav kav is offline
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Re: Color Space Choices for Nikon 5000 Scans

I forgot to ask this stuff. Are you scanning negatives or film? Are you actually able to locate a scanner profile in your computer that matches up? Not something generic but one that was actually imported by the installation of your nikon scanner software. I see you saying convert to prophoto but there's no real data in the conversation of what it's tagged with before this, and no comparison as to if prophoto is a good match. Like are you importing it into an sRGB workspace without assigning a profile and then hitting convert or is it tagged with something accurate? Even if it is a good match, it still doesn't display that accurately, and it can produce some wacky results, not all of which you'll see on screen.
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  #22  
Old 08-01-2010, 05:56 PM
stlsailor stlsailor is offline
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Re: Color Space Choices for Nikon 5000 Scans

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Are you scanning negatives or film?
For now Kodachrome and Ektachrome positives. Haven't started on the negatives yet.

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Are you actually able to locate a scanner profile in your computer that matches up? Not something generic but one that was actually imported by the installation of your nikon scanner software.
The scanner hardware profile is loaded automatically in Nikon Scan 4. It's CMS allows you to select the color space for the image. The color space choices potentially appropriate for Windows are:

(1) Nikon Adobe RGB (1998)
which is very close to Adobe RGB (1998) based on image and histogram comparisons though not exactly identical,

(2) Wide Gamut RGB
which it says was designed by Adobe and is the same thing as Wide Gamut RGB was in Photoshop 5.0,

(3) Wide Gamut RGB compensated
to allow it pick up more of what the scanner can scan in the blue area, and

(4) Scanner RGB
which is primarily for use in Nikon Scan 4 and no ICC profile is passed to the host program.

It appears that for Scanner RGB no color space is embedded, but the EXIF data incorrectly shows it as sRGB.

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I see you saying convert to prophoto but there's no real data in the conversation of what it's tagged with before this, and no comparison as to if prophoto is a good match. Like are you importing it into an sRGB workspace without assigning a profile and then hitting convert or is it tagged with something accurate?
So, when I convert to ProPhoto I'm scanning in Scanner RGB and then telling PS CS5 to convert it when I open the file. Whether it in fact is simply assigning it because there is no embedded profile, or whether it converts it based on an assumed sRGB profile I don't yet know.

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Even if it is a good match, it still doesn't display that accurately, and it can produce some wacky results, not all of which you'll see on screen.
I'm not sure what you mean by this.

I did some comparisons of histograms from 3 images. I attached them to this message because seeing them is better than my trying to describe them. In every case, though, Adobe RGB had a slightly wider histogram which seems to say to me that NS4 was actually converting from what it thought was sRGB, not simply assigning the color space. I'd be interested in what conclusions you or others might draw from these histograms.

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I've tried prophoto for photos with a lot of saturation that I was trying to preserve, but it doesn't match up with a typical viewing setup. It's a D50 gamma 1.8 profile which isn't exactly comparable to modern display hardware. Were you looking at it because it was similar to the scanner's profile?
I was looking at it because (a) it seemed like the most logical choice to match either the scanner's profile or Wide Gamut profiles, and (b) the books I bought when I upgraded to PS recently all recommended it (for 16-bit scans, not 8-bit). Up until now I've pretty much used Adobe RGB (1998).

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Also does adobe 1998 show a lot of clipping when going from the scanner profile?
The histograms I uploaded may show more than I could explain in words.


Dale
Attached Images
File Type: jpg Image K - Histograms 2.jpg (45.6 KB, 6 views)
File Type: jpg Image P - Histograms.jpg (45.1 KB, 5 views)
File Type: jpg LK - Histogram.jpg (48.8 KB, 5 views)
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  #23  
Old 08-02-2010, 12:06 AM
stlsailor stlsailor is offline
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Re: Color Space Choices for Nikon 5000 Scans

Two additional pieces of information. First, I found some information that indicates in an earlier version of Photoshop that if the EXIF data indicated an sRGB color space, then that color space was used to try to convert it. I haven't been able to confirm that CS5 works the same way, but it's reasonable to suppose it does, especially since the narrower histograms seemed to suggest this.

Second, I tried saving a .nef file (which it turns out only seems to save in Adobe RGB) after finding out that PS would edit it. In the few instances I tried, it had better image quality than the TIFF files, and it opens in ACR. Note in one of these files I may have forgotten to reset the auto adjustments in ACR, though I don't think that made much difference.

A couple of updated histograms are attached.

Dale
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File Type: jpg Image K - Histograms 2.jpg (62.6 KB, 4 views)
File Type: jpg LK - Histogram.jpg (73.0 KB, 4 views)
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  #24  
Old 08-03-2010, 09:24 PM
kav kav is offline
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Re: Color Space Choices for Nikon 5000 Scans

Once more, why prophoto? Your desire to use it suggests that you don't understand color gamuts because it doesn't map well to any device I can think of. Speculating on future devices is silly. If you want that, keep the scanner rgb because it's a better representation of your data in actual numbers. If you want to make adjustments in a space that actually can be viewed on a monitor with a reasonable degree of accuracy you probably want adobe 1998 but convert to srgb on a copy if you're posting it to the web or something for online viewing. Picking a non standard profile that doesn't match anything particularly well is pointless. If the point was just to have a really big color gamut we'd all work in LAB. It's also not so much a matter of "supported". You could still use colormatch rgb if you wanted to and photoshop would still recognize it, but it's not a good match to modern display hardware. A scanner profile actually embedded, meaning that it's tagged to the image would give you maximum color preservation with little to no correction made in the scanning software. It will just be annoying.
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  #25  
Old 08-04-2010, 08:38 AM
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Re: Color Space Choices for Nikon 5000 Scans

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Originally Posted by kav View Post
Once more, why prophoto?
For raw workflows, its a no brainer, Adobe RGB is too small to contain the possible gamut of captures (note that the scene gamut as well as the so called capture gamut plays a role). For scanners, the native color space is an ideal archive space but not necessarily an editing space. It may not be well behaved where R=G=B is neutral. All synthetic RGB working space are wel behaved. If the gamut of the scanner color space is larger than Adobe RGB (1998), its not the editing working space space to be using, you’ll clip colors. ProPhoto will contain those colors just fine.

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Your desire to use it suggests that you don't understand color gamuts because it doesn't map well to any device I can think of.
No working space necessarily does. To quote myself to save time, the old “round peg in square hole analogy is useful:
Quote:
Gamut mismatch (fitting round pegs in square holes)

It IS true that the wider the granularity in a color space, the harder it is to handle subtle colors. This is why wide gamut displays that can't revert to sRGB (current LCD technology doesn't allow this.) are not ideal for all work (ideally you need two units).

There are way, way more colors that can be defined in something like ProPhoto RGB than you could possibly output, true. But we have to live with a disconnect between the simple shapes of RGB working space and the vastly more complex shapes of output color spaces to the point we're trying to fit round pegs in square holes. To do this, you need a much larger square hole. Simple matrix profiles of RGB working spaces when plotted 3 dimensionally illustrate that they reach their maximum saturation at high luminance levels. The opposite is seen with print (output) color spaces. Printers produce color by adding ink or some colorant, working space profiles are based on building more saturation by adding more light due to the differences in subtractive and additive color models. To counter this, you need a really big RGB working space like ProPhoto RGB again due to the simple size and to fit the round peg in the bigger square hole. Their shapes are simple and predictable. Then there is the issue of very dark colors of intense saturation which do occur in nature and we can capture with many devices. Many of these colors fall outside Adobe RGB (1998) and when you encode into such a space, you clip the colors to the degree that smooth gradations become solid blobs in print, again due to the dissimilar shapes and differences in how the two spaces relate to luminance.
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Speculating on future devices is silly.
NOT if you are facing the decision to throw away data and you don’t want to paint yourself into a corner.

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If you want that, keep the scanner rgb because it's a better representation of your data in actual numbers.
True. It may not be the best editing color space. There is no reason not to archive the scanner data and move on assuming you don’t introduce any issues editing by the numbers (assuming neutrals are equal proportions of RGB). Otherwise, edit and archive in the scanner color space.

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If you want to make adjustments in a space that actually can be viewed on a monitor with a reasonable degree of accuracy you probably want adobe 1998 but convert to srgb on a copy if you're posting it to the web or something for online viewing.
True. But again, if the data is wider in gamut than Adobe RGB (1998) and your output device is as well, do you clip colors so you can see them, temporarily on your wide gamut display, or use the colors on output and get a less than fully accurate representation of the data on the display? For most, they want the printer to be receiving as much data possible.


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If the point was just to have a really big color gamut we'd all work in LAB. It's also not so much a matter of "supported".
Here we disagree. There are no Lab capture devices. You have to produce a conversion just to get into Lab, from in this case, scanner RGB. Might as well use it or ProPhoto. There are no Lab output devices, you have to convert again (although you would from an RGB working space). Lab has some real nasty behaviors that make it a poor editing space and while color described in Lab are more “real” than the two imagery primaries in ProPhoto (which fall outside of human gamut), users are going to be far better off in a wide gamut RGB space. Lab has a number of flaws that make it problematic Keep in mind that CIELab was just an attempt to create a perceptually uniform color space where equal steps correlated to equal color closeness based on the perception of a viewer. The CIE didn't claim it was prefect (cause its not). Most color scientists will point out that Lab exaggerates the distance in yellows and consequently underestimate the distances in blues. Lab assumes that hue and chroma can be treated separately. There's an issue where hue lines bend with increase in saturation perceived by viewers as an increase in both saturation and a change in hue when that's really not supposed to be happening. Further, according to Karl Lang, there is a bug in the definition of the Lab color space. If you are dealing with a very saturated blue that's outside the gamut of say a printer, when one uses a perceptual rendering intent, the CMM preserves the hue angle and reduces the saturation in an attempt to make a less saturated blue within this gamut. The result is mathematically the same hue as the original, but the results end up appearing purple to the viewer. This is unfortunately accentuated with blues, causing a shift towards magenta. Keep in mind that the Lab color model was invented way back in 1976, long before anyone had thoughts about digital color management.
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  #26  
Old 08-04-2010, 02:39 PM
stlsailor stlsailor is offline
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Re: Color Space Choices for Nikon 5000 Scans

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For scanners, the native color space is an ideal archive space but not necessarily an editing space. It may not be well behaved where R=G=B is neutral. All synthetic RGB working space are wel behaved. If the gamut of the scanner color space is larger than Adobe RGB (1998), its not the editing working space space to be using, you’ll clip colors. ProPhoto will contain those colors just fine.
The two options which appear closes to the scanner color space are either Wide Gamut or Wide Gamut compensated. They are equivalent to Nikon AdobeWide RGB 4.0.0.3000 with one exception. The compensated one "redefines Wide Gamut RGB to include all the colors that can be output from the scanner. Because many of the colors that can not be expressed in Wide Gamut RGB occur in the blue portion of the gamut, the level of detail in the blue area has been greatly increased (because the gamut has been expanded in a nonlinear fashion to incorporate just those colors that could not otherwise be expressed, it can not be represented in chromaticity diagrams using a standard RGB triangle). As is the case with Wide Gamut RGB, most of the colors defined in this profile can not be reproduced on monitors and printers."

Question 1: Am I correct in thinking that (a) AdobeWide is the closest thing to the native color space of the scanner, and (b) that it's probably narrower than ProPhoto RGB?


When I open them in PS they open in ACR because they are .nef.

Question 2: The working options in ACR agive Adobe RGB and ProPhoto RGB but not Adobewide RGB. Therefore there seems to be no reason to use wide gamut RGB for a .nef file unless I decided to convert it into the wider ProPhoto space (which would not clip any scanner colors but will be wider than needed). Is this correct?

Dale
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  #27  
Old 08-04-2010, 02:43 PM
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Re: Color Space Choices for Nikon 5000 Scans

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Originally Posted by stlsailor View Post
Question 1: Am I correct in thinking that (a) AdobeWide is the closest thing to the native color space of the scanner, and (b) that it's probably narrower than ProPhoto RGB?
I really have no idea. I don’t know what the scanner software is doing in the CMS path, that there indeed is “raw” RGB scanner data being provided to you, with the proper input profile (which ideally you’d make). The scanner is capable of producing what it produces, are you getting that out the software backend? That’s something Nikon would have to help you with.
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  #28  
Old 08-04-2010, 04:12 PM
kav kav is offline
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Re: Color Space Choices for Nikon 5000 Scans

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Originally Posted by andrewrodney View Post
I really have no idea. I don’t know what the scanner software is doing in the CMS path, that there indeed is “raw” RGB scanner data being provided to you, with the proper input profile (which ideally you’d make). The scanner is capable of producing what it produces, are you getting that out the software backend? That’s something Nikon would have to help you with.
I think you're misinterpreting what I was getting at slightly. We weren't talking about exporting with prophoto but rather converting to it after. If you bring up prophoto in any color management software you'll see that while it is large, it does clip vs. some spaces in certain areas when mapped against them too, and aside from that doesn't display that well on screen. Just by what it includes and what it doesn't I never found the space to be ideal for anything. I was suggesting if you're outputting (from the scanner software) in a wider gamut such as the scanner profile archiving in that if you're not going to use a working profile for final saves. Also just to clarify Adobe RGB is a little different. I suggested Adobe 1998. I have them as 2 different profiles. I'm going to see if google can help me find info on the settings/hardware profile of that machine.
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  #29  
Old 08-04-2010, 04:17 PM
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andrewrodney andrewrodney is offline
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Re: Color Space Choices for Nikon 5000 Scans

The best, purest data is the scanner RGB data defined by a profile which can then be converted into ProPhoto or Adobe RGB or whatever. Its totally unclear with the conversion path is for this software driver. For all we know, the conversion is Native RGB (which you can’t get ahold of) to some other RGB color space to ProPhoto. We don’t know the engine (CMM). It would be a lot more useful to get scanner RGB with a custom input profile, then worry about what RGB working space you’ll convert to later in Photoshop (where you have full control).
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  #30  
Old 08-04-2010, 04:30 PM
kav kav is offline
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Re: Color Space Choices for Nikon 5000 Scans

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Originally Posted by andrewrodney View Post
The best, purest data is the scanner RGB data defined by a profile which can then be converted into ProPhoto or Adobe RGB or whatever. Its totally unclear with the conversion path is for this software driver. For all we know, the conversion is Native RGB (which you can’t get ahold of) to some other RGB color space to ProPhoto. We don’t know the engine (CMM). It would be a lot more useful to get scanner RGB with a custom input profile, then worry about what RGB working space you’ll convert to later in Photoshop (where you have full control).
I hadn't thought of that, but you could be right. Could also be something like input profile --> LAB ---> Adobe/prophoto/etc.

Regarding custom input profiles, don't they ship IT8 targets with that model?
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