George Koulomzin
New member
fair enough....
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NEC 2490 / 2690 / Sean Reid / Luminous Landscape
- Thread starter Edward Bussa
- Start date
Edward Bussa
Member
I've been pondering this one since the comment was made.
The interpretation I've settled on is this: In the software used to manipulate your image (ie, lightroom), the adjustments are made via some predefined scale, such as 1 to 100. This divides your gamut into 100 equal parts. This means that on a wide gamut monitor, each division covers "more ground" or "color" or "gamut". Therefore, you may find yourself in a situation where the adjustment you want is in between two adjustment increment values such 76 & 77.
I know I have ran into adjustment scale increments in lightroom that border on being too wide for my tastes even on my RGB gamut monitor.
The interpretation I've settled on is this: In the software used to manipulate your image (ie, lightroom), the adjustments are made via some predefined scale, such as 1 to 100. This divides your gamut into 100 equal parts. This means that on a wide gamut monitor, each division covers "more ground" or "color" or "gamut". Therefore, you may find yourself in a situation where the adjustment you want is in between two adjustment increment values such 76 & 77.
I know I have ran into adjustment scale increments in lightroom that border on being too wide for my tastes even on my RGB gamut monitor.
George Koulomzin
New member
Another way of saying this is that too many distinguishable colors are quantized into the same 8 bit value (in the case of 24 bit color). Since a device can display only one color for each of the 256 possible values (presumably some middle color), the color distance between two adjacent values (say 127 and 128) might be perceptible. Color would then no longer appear to be continuous.
We need 16 bit paths to our monitors, printers, etc....
Until we get them, would it be correct to say one should work in the smallest color space which will fit the gamut of the image?
We need 16 bit paths to our monitors, printers, etc....
Until we get them, would it be correct to say one should work in the smallest color space which will fit the gamut of the image?
Edward Bussa
Member
I'm starting to rethink this and am questioning if I can reason out what the issue really is.
The adjustments in lightroom can take you from R0 to R255 (using a scale from -100 to +100), right? A value of R128 should look identical on both the standard gamut monitor and the wide gamut monitor as should R129 and R130, etc. Only when you get into the extreme settings like R251 does the image potentially start to look and behave different, right?
On the standard gamut monitor, the color will "stick" at, say, R245 and fail to display any setting beyond that because R245 is at the limit of its gamut. So, only when you crank the Red up to, say, R251 do you begin to see a difference in the way the monitors behave, right?
In other words, the software makes adjustments from NO RED (R0) to ALL RED (R255). This is an absolute thing, not reliant on what colorspace your monitor or your image are using, right? The colorspace just determines what color values your image can store or your monitor can display, no?
I'm not sure if this is true or if the software actually adjusts what the R values mean (R0, R128, R255) based on the color gamut of the image... ?
The adjustments in lightroom can take you from R0 to R255 (using a scale from -100 to +100), right? A value of R128 should look identical on both the standard gamut monitor and the wide gamut monitor as should R129 and R130, etc. Only when you get into the extreme settings like R251 does the image potentially start to look and behave different, right?
On the standard gamut monitor, the color will "stick" at, say, R245 and fail to display any setting beyond that because R245 is at the limit of its gamut. So, only when you crank the Red up to, say, R251 do you begin to see a difference in the way the monitors behave, right?
In other words, the software makes adjustments from NO RED (R0) to ALL RED (R255). This is an absolute thing, not reliant on what colorspace your monitor or your image are using, right? The colorspace just determines what color values your image can store or your monitor can display, no?
I'm not sure if this is true or if the software actually adjusts what the R values mean (R0, R128, R255) based on the color gamut of the image... ?
George Koulomzin
New member
First off, I am not familiar with light room, and I presume that the +- 100 comes from lightroom. The actual underlying values for 8 bit color would be 0-255.
I think your original intuition was correct. Here's another way of saying it. Suppose you have a color space that can represent all color of interest to you. Think of aRGB as a subset of that, and sRGB as a subset of aRGB. If you are limited to 8 bit color (and for simplicity lets stick to just the red axis) the reds must be represented by values in the range 0-255. Stretch a rubber band across the sRGB space, mark it off into 256 equal segments, and the all the colors in any one segement must be represented by the same number. Now take that rubber band and stretch it out further so that it spans all of the aRGB space. As you do so, you will note that a) the marks on your rubber band move, and that the distance between the marks increases. Thus the color represented by 127, for example, in one space is not the same as the color represented by 127 in the other space, and furthermore, a larger range of actual colors is lumped in to the same 127 value.
Look at http://www.cambridgeincolour.com/tutorials/sRGB-AdobeRGB1998.htm; this site also addresses the question I had earlier about whether one should operate in the smallest color space your image will fit into....
Also, look at the CIE 1931 xy Chromaticity diagram on http://www.normankoren.com/color_management.html#Sci_nutshell; this diagram will help when you visualize the rubber band stretching across a larger space (albeit not on the red axis).
Hope this helps...
Andrew Rodney
New member
The underlying color space used in LR and ACR is ProPhoto primaries with a linear tone curve (1.0). The percentages are a conversion of this underlying processing space mapped to an sRGB tone curve (2.2). In a way, the numbers here and in other app’s are kind of meaningless since they don’t actually represent the data you’re working with. Does a liter of gas tell you anything more about the gas itself than a gallon of gas? In CMYK, you’re still dealing with 0-255 8-bit scale while the numbers you see are 0-100% for ink in what could be a “16-bit” document. Another disconnect.
As to color spaces, the effect of larger spaces with the same encoding values, this might help:
http://www.ppmag.com/reviews/200509_rodneycm.pdf
http://www.ppmag.com/reviews/200510_rodneycm.pdf
Edward Bussa
Member
Thanks for the timely links.
So LR and ACR consistently work in the ProPhoto color space. So all the adjustments scales span that underlying wide gamut "process space", at least for raw files.
From the articles you linked Rodney, I learned that the ultimate number of color aliases (adjustment levels) you have to work with is based on the bit-depth of the file. I had not realized the implications and/or differences between color space and file bit-depth. Thank you.
Now my Nikon D300 can capture to 14-bit files. I'm not sure how this plays into the adjustment scheme in LR. Is LR aware of the bit-depth of my raw file?
When I make an adjustment in LR, it renders the change to my screen. Since LR is always working in the ProPhoto color/processing space, the only difference the gamut on my monitor would make is whether or not I can see the colors being rendered.
But I think this might be where the sRGB tone curve comes into play. This is being introduced by my monitors color profile. The rendering from LR is being mapped to my monitors gamut, right? Now I begin to see how a wide gamut monitor can cause an adjustment to be too coarse. Essentially, the tone curve from a wide gamut monitor's profile is "longer", correct?
So LR and ACR consistently work in the ProPhoto color space. So all the adjustments scales span that underlying wide gamut "process space", at least for raw files.
From the articles you linked Rodney, I learned that the ultimate number of color aliases (adjustment levels) you have to work with is based on the bit-depth of the file. I had not realized the implications and/or differences between color space and file bit-depth. Thank you.
Now my Nikon D300 can capture to 14-bit files. I'm not sure how this plays into the adjustment scheme in LR. Is LR aware of the bit-depth of my raw file?
When I make an adjustment in LR, it renders the change to my screen. Since LR is always working in the ProPhoto color/processing space, the only difference the gamut on my monitor would make is whether or not I can see the colors being rendered.
But I think this might be where the sRGB tone curve comes into play. This is being introduced by my monitors color profile. The rendering from LR is being mapped to my monitors gamut, right? Now I begin to see how a wide gamut monitor can cause an adjustment to be too coarse. Essentially, the tone curve from a wide gamut monitor's profile is "longer", correct?
Michael Fontana
pro member
Edward
why do you profile your display into sRGB?
Coming from a huge gamut - actually it's in LR Melissa RGB which is a derivate from PPRGB - if you have a wide gamut display, it doesn't makes sense to reduce it to sRGB if you want to edit your photos.
why do you profile your display into sRGB?
Coming from a huge gamut - actually it's in LR Melissa RGB which is a derivate from PPRGB - if you have a wide gamut display, it doesn't makes sense to reduce it to sRGB if you want to edit your photos.
Edward Bussa
Member
Michael, thank you for your concern! Contrary to my misleading statemnts 
my monitor actually is an RGB gamut monitor (2490WUXi)...
my monitor actually is an RGB gamut monitor (2490WUXi)...
Asher Kelman
OPF Owner/Editor-in-Chief
Wow,
It’s so useful sometimes to remind us of great threads of many years back!
Now where are your own photographs?
That’s what clarifies your intent and creates your welcome by all of us!
Asher