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November 28, 2008
Question

notebook display for image editing?

  • November 28, 2008
  • 24 replies
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Hi. Is there a high-end wide-gammut notebook display for color-critical image editing ?
What notebook would you recommend if you HAD TO recommend one ?
thanks.
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    24 replies

    Participating Frequently
    December 1, 2008
    Hi Gernot Hoffmann

    It's bossible to obtain this profille (oRGB)?

    thank
    Participating Frequently
    December 1, 2008
    Actually, I would like to replace 'a disaster' by 'ugly':

    Let's have a look at the graphic on p.3 in this doc:
    http://www.fho-emden.de/~hoffmann/gamcomp18062006.pdf

    It shows the chromaticity diagram with gamut triangles for
    sRGB, aRGB=Adobe RGB, pRGB=ProPhoto RGB and my private
    color space oRGB=OptiRGB.
    Furtheron more than 1100 spot inks and the primary inks for
    CMYK ISOCoated and for my inkjet, where 'inks' means here
    'colors of inks on coated paper under D50'.

    Almost all these colors are in-gamut for the wide-gamut color
    space oRGB. Compared to this, pRGB seems to be far too large,
    which causes quantization problems, unless 16bpc is used.
    The primaries for green and blue are non-existing colors
    (mathematical constructs), and, what is less obvious, the
    primary for red is practically invisible because of lacking
    power at 700nm. 255,0,0 in pRGB should be black, but it isn't
    in PhS.
    That's what I meant by 'disaster'. So we have an RGB space
    where we cannot choose for only one channel 255 (or the largest
    value for 16 bpc). More precisely: in PhS CS2 we can choose
    such a value but there is no warning.
    Plenty colors inside the human gamut (which is not indicated
    in PhS) are out-of-numberspace in Lab, where a*,b* are confined
    between -128 and +127.
    In oRGB this happens as well, but only for a smaller percentage
    of possible colors.
    The doc shows on the following pages the truly exaggerated range
    of pRGB in Lab.

    This somewhat strange color space has its roots in the RIMM/ROMM
    concept by Kodak, as found here:
    Ph.Green+Lindsay MacDonal Ed.
    Colour Engineering
    Chapter 14
    K.Spaulding+E.Giorgianni
    Implementation of device-independent color at Kodak

    RIMM is scene-referred, ROMM is device-referred.
    RIMM can be considered as an RGB space between camera RAW
    and the ICC Profile Connection Space (PCS). Concerning the
    primaries and some other features it's the same as pRGB.

    The authors are talking about nonlinear manipulations for R'G'B'
    (gamma encoded) simultaneously to all channels, but without
    specifying these manipulations. We can imagine for instance a
    contrast improvement by an S-like Curve.
    Everybody knows, that this can cause strong color shifts,
    depending on the strength of the manipulation.
    RIMM/ROMM was optimized for minimal hue variations (as defined
    as deviations from straight lines in an a*,b* projection).
    The authors are comparing their good result with the bad result
    for some other nameless wide gamut space.

    Now, for what is it good - useful strategies ten years ago ?
    For nothing, because nowadays and in future manipulations of
    this type are done professionally in Lab.

    Surprisingly, the oversize of pRGB, as defined by the gamut
    triangle in xy, or by a volume in Lab, was not chosen so large
    because of the necessary gamut size but because of the hue
    robustness against 'luminosity' changes.

    Best regards --Gernot Hoffmann
    December 3, 2008
    You seem to be assuming that, upon conversion to ProPhoto RGB, and/or subsequent to an image edit, certain colors in the image will drift into the "imaginary" region of ProPhoto RGB and be forever lost, with dire consequences -- or "disastrous", or "ugly".

    In my years as an imaging professional using fully color-managed late-binding workflows I have detected no ProPhoto RGB "misbehavior" that was so glaring that I or others noticed it.

    Seems to me that your argument is informed more by Dan Margulis' own prejudices against wide-gamut RGB color spaces than by arguments whose validity I can recognize based on my own experience. I suggest that you take his "advice" with a generous grain of salt.

    >RIMM can be considered as an RGB space between camera RAW and the ICC Profile Connection Space

    You can say that RIMM is the intermediator between the input scene's Raw data and the ROMM/ProPhoto RGB space that one can use for output, storage and manipulation -- but it should not be implied that Raw itself is a color space.

    A color space has primaries and tonal curves. Camera Raw is simply a mathematical construct for input that needs to be translated into colors usable for output. It has no defined primaries or tonal curves.

    >The authors are comparing their good result with the bad result for some other nameless wide gamut space.
    >Now, for what is it good - useful strategies ten years ago ? For nothing, because nowadays and in future manipulations of this type are done professionally in Lab.

    That is, by Mr. Margulis and those who get lost along with him in his "canyons". Not by me or other professionals that I share knowledge with. You wish to sound as if your advice is based on widespread practice, but it's actually free advertising for someone who I have to admit is a sharp self-marketer who, on his way to dubious fame, also manages to dupe intelligent people.

    >Surprisingly, the oversize of pRGB, as defined by the gamut triangle in xy, or by a volume in Lab, was not chosen so large because of the necessary gamut size but because of the hue robustness against 'luminosity' changes.

    Not true. The gamut size was very much a core consideration in creating RIMM/ROMM, not secondary to what you call "hue robustness". It was a matter of finding the best compromise, among other factors, between quantization due to "out-of-locus" primaries, efficient encoding, gamut large enough to encompass real-world surface colors and suitability for storage and color/tonal manipulation.

    To quote:

    >ROMM RGB was designed to provide a large enough color gamut to encompass most common output devices, while simultaneously satisfying a number of other important criteria
    i [described on page 2 of the PDF document cited below].
    >[...] Increasing the gamut can only be achieved by trading off against correspondingly larger quantization errors. If the primaries are chosen to include the maximum possible chromaticity gamut (i.e., the entire area within the spectrum locus), a significant fraction of the color space would correspond to imaginary colors located outside that region. Therefore, in any encoding using such a color space, there would be wasted code values that would never be used in practice. This would lead to larger quantization errors in the usable part of the color space than would be obtained with different primaries defining a smaller chromaticity gamut.
    b It is therefore desirable to choose primaries with a gamut that is big enough but not too big.
    >[...] he primaries selected for RIMM/ROMM RGB [...] encompass the gamut of real world surface colors,
    b without devoting a lot of space to non-realizable colors outside the spectrum locus.

    >"Reference Input/Output Medium Metric RGB Color Encodings (RIMM/ROMM RGB)"
    Ramón G Castañeda
    Inspiring
    December 1, 2008
    >On the contrary, ProPhoto RGB contains two of three
    primaries which are non-existing colors (chromaticities
    outside the horseshoe contour). Mathematically possible
    but practically a disaster, IMO.

    Just as Marco did in post #13, I found the above quoted statement in Prof. Hoffmann's #11 disconcerting. I hope further discussion of this is forthcoming.
    Participating Frequently
    November 29, 2008
    Thank you Gernot Hoffmann!
    Participating Frequently
    November 29, 2008
    Kokii,

    OptiRGB is an exercise - how to define an RGB space
    which contains almost all 'relevant' colors and which
    has primaries which really exist as physical colors
    (here as pure spectral colors).

    On the contrary, ProPhoto RGB contains two of three
    primaries which are non-existing colors (chromaticities
    outside the horseshoe contour). Mathematically possible
    but practically a disaster, IMO.

    Best regards --Gernot Hoffmann
    November 29, 2008
    A "disaster", uh?

    We'll have to tell all those fools who use ProPhoto RGB pronto, then, and let them know with no further delay that all those images that they produced from ProPhoto RGB, and thought looked beautiful, are actually horrible. Because you say so.

    Quick!
    Participating Frequently
    November 29, 2008
    Hi Gernot Hoffmann


    what this "Opti RGB" in page 15?

    thank
    Participating Frequently
    November 29, 2008
    Mark,

    concerning the interpretation of gamuts in the chromaticity
    diagram you are partly right.
    Partly, because this diagram is a perspective projection
    of the 3D color space XYZ onto a 2D plane.

    More important (for me) is the question, which RELEVANT
    colors are in-gamut or out-of-gamut in several color
    spaces.
    Relevant are IMO: all Pantone Spot colors, because these
    are (when printed) the most vivid real world colors;
    then the printer inks, because these define the reproduction;
    and finally the colors of photographic targets, because
    these were considered as relevant for real world colors
    by color scientists.

    Pages 15-19 here are showing the results:
    http://www.fho-emden.de/~hoffmann/swatch16032005.pdf

    Stroked symbols for out-of gamut, filled for in-gamut.

    It's perhaps disappointing that vivid orange or yellow
    is out-of-gamut for aRGB, but eventually not for printing.

    But here comes the solution: in aRGB and even in sRGB
    one can boost colors in Lab. From there one can convert
    directly into CMYK.
    This aspect was always forgotten by 'calibrationist'.
    A quite common opinion is, that a camera has to acquire a
    scene correctly. That's wrong (except for reproduction).
    The image can be converted by manipulations into some-
    thing more pleasing.

    Best regards --Gernot Hoffmann
    Christian_Davideck
    Known Participant
    May 23, 2009

    Gernot Hoffmann wrote:

    Gamuts cannot be compared
    by percentage.

    (Mark_J_Peterson) wrote:

    Gernot, you can compare Gamuts by percentage, if you display the gamuts as triangles in the CIE 1931 xy chromaticity diagram and compare the triangles' area. Of course, it's not an unproblematic and objective measurement due to the diagram's distortion in the direction of the green point, but still it gives you an idea

    Gernot Hoffmann wrote:

    concerning the interpretation of gamuts in the chromaticity
    diagram you are partly right.
    Partly, because this diagram is a perspective projection
    of the 3D color space XYZ onto a 2D plane.

    Gernot, one could also compare the real gamut volumes in 3D (as opposed to their 2D projection). Wouldn't this be a correct gamut comparison then, despite of your original statement, that gamuts cannot be compared by percentage ?

    Known Participant
    November 29, 2008
    Gernot, you can compare Gamuts by percentage, if you display the gamuts as triangles in the CIE 1931 xy chromaticity diagram and compare the triangles' area. Of course, it's not an unproblematic and objective measurement due to the diagram's distortion in the direction of the green point, but still it gives you an idea (for example, considerably smaller than Adobe RGB, same size, or a bit larger). So I'd take the percentages as "rough measurement" ...

    In my opinion, it's not marketing nonsense, because the reviewing person didn't favour one brand over the other. I just think that he/she doesn't truly understand the subject. For once, I think he/she confuses NTSC with AdobeRGB (which was subsequently used for all comparisons). And secondly, I think this is entirely false:

    >HP didnt give their display quality in terms of the percentage of the gamut, but their press release did say the Elitebooks DreamColor LCD could display over 16 million colors. The Adobe RGB color gamut has approximately 16.7million colors in it, and after doing a little math were given a 96% gamut representation. Not bad at all.

    Because in my opinion (comment I made there, awaiting moderation ... will probably never see the light of day over there):

    >The Adobe RGB color gamut has approximately 16.7million colors in it. -> This statement is false. Adobe RGB, sRGB (and all other RGB color spaces for that matter) encompass an infinite amount of colors. The total amount of colors used by a given hardware device or software application depends on the bit depth it uses, from 1 bit (=2 colors, usually black and white) to 24bit (=16,7 Mio colors) and more (48bit, 96bit, etc.). So the calculation leading to 96% gamut representation is wrong. Because RGBcolor spaces, define (among other things), where red, green and blue are situated within the CIE Lab color space. How fine the graduation(=increments/nuances) are - and thus how many colors are used - depend on the bit depth."
    December 1, 2008
    >HP didnt give their display quality in terms of the percentage of the gamut, but their press release did say the Elitebooks DreamColor LCD could display over 16 million colors. The Adobe RGB color gamut has approximately 16.7million colors in it, and after doing a little math were given a 96% gamut representation. Not bad at all.

    What utter nonsense. Gamut volume and bit depth are two totally separate things.

    It's always shocking (though no longer unusual) to see someone writing a review who understands nothing of the basics of what he is writing about. Where was this review posted? Who is this writer?

    Any color space, even the smallest ones, can be subdivided into a theoretically infinite number of steps depending on the bit depth used. The only limit is the processing power available. In 8-bit color spaces with 3 primaries (like RGB) you have 16.7 million [2^(8*3)], in 16 bits you have 281 trillion [2^(16*3)], and so on. None of that increases the gamut by one little tiny amount.

    Gamut volume, on the other hand, is the portion of human-visible color range that a given color space is capable of reproducing. The maximum possible color range is (roughly speaking) the volume of Lab, which is a device-independent color space, like XYZ or LCH and a few others. But no matter how gamut volume is expressed (by percentage or by using absolute numbers), the "number of colors" is *never* the way it's done, since it's meaningless for the reasons stated above.
    Participating Frequently
    November 29, 2008
    Quoted:
    "The same is true of printers which can capture a wider gamut
    than your screen can display. More recent laptop monitors are
    LED backlit, and while at first this was only an incremental
    improvement, in recent months laptops have come out that can
    actually exceed 100% of the NTSC color gamut."

    The article is marketing nonsense. Gamuts cannot be compared
    by percentage. Nobody else would use NTSC as a reference.

    Best regards --Gernot Hoffmann
    Known Participant
    November 29, 2008
    Anyway, the gamut is impressive I think. It's a considerably improvement compared to the colors laptop monitors commonly were able to display.