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D
deeland
Inspiring
August 15, 2016
Answered

Inconsistent Numerical Colour Values

  • August 15, 2016
  • 3 replies
  • 5301 views

Hi folks

I'm on what I think is a bug hunt, that I'm pretty sure I discovered some years ago, but can't find the original posts.

It involves the numerical values of colours across Adobe desktop applications and Adobe Color CC.

The applications I've found issues in, are the following:

Illustrator, Photoshop, Dreamweaver and the online resource, Adobe Color CC

Basically, I have found discrepancies in numerical values within the Color Palette Window, and the Color Picker Window, and whatever you want to call the window in Dreamweaver.

I've used the iOS app myPANTONE as my starting reference. Follows, some values for yourselves, to see if you can relocate this issue. NOTE: some modes are not available across all applications/resources:

SOURCE

PANTONE+ SOLID COATED

LAB

sRGB

HTML

CMYK

RGB

HSL

HSB

WEB RGB

# HEX (CSS)

WEB RGB (SAFE)

# HEX (CSS) (SAFE)

CSS RGB

CSS HSL

myPANTONE

368 C

69.93 -40.24 62.99

120 190 32

78BE20

65 0 100 0

http://rgb.to

368 C

65, 0, 100, 0

120, 190, 32

87, 71, 44

87, 83, 75

78be20

66cc33

120, 190, 32

87, 71%, 44%

Adobe Illustrator (Colour Palette)

368 C

59.45 0 100 0

119 188 31

86.37 83.47 73.91

77BC1F

77BC1F

66CC33

65CB32

Adobe Illustrator (Colour Picker)

368 C

59 0 100 0

119 188 31

86 83 73

77BC1F

66CC33

Adobe Illustrator (Colour Palette)

7737 C

65 0 100 0

101 179 46

95.19 74.13 70.2

65b32e

65B22E

66CC33

65CB32

Adobe Illustrator (Colour Picker)

7737 C

65 0 100 0

101 178 46

94 74 69

65B22E

669933

Adobe Photoshop (Colour Palette)

368 C

70 -40 63

60 0 100 0

142 187 56

81 70 73

8ebb38

99cc33

Adobe Photoshop (Colour Picker)

368 C

70 -40 63

60 0 100 0

142 187 56

81 70 73

8ebb38

99cc33

Adobe Photoshop (Colour Palette)

66 -42 56

65 0 100 0

129 177 62

85 65 70

81b13e

999933

Adobe Photoshop (Colour Picker)

369 C

66 -42 56

65 0 100 0

129 177 62

85 65 70

81b13e

999933

Adobe Dreamweaver (Colour Sliders)

65 0 100 0

79 167 54

107 68 66

4FA736

Adobe Dreamweaver (CSS Code)

65 0 100 0

hsl(106,44%,48%)

5EB245

Hopefully, this pasted table comes out okay. Let me know if it doesn't display well for you.

    This topic has been closed for replies.
    Correct answer D Fosse

    Well, it's been lovely. Thank you for your time.

    I thought it was interesting and was looking for a reason the numbers were off.

    Basically, one can expect small discrepancies — it's just the way it is.

    Cheerio!


    Yes, and you've been given the reason, you just don't like it and choose to reject it. That's your choice.

    So just to sum up for anyone else reading this - any given color will produce different RGB numbers, depending on what color space the numbers refer to. Any set of RGB numbers will produce different colors, depending on what color space the numbers are assigned to.

    That's the long and short of it. This question is answered.

    It's not rocket science, unless you see color management as the enemy. Then you'll quickly get into trouble - especially since these applications are designed to work with full color management. Their whole architecture revolves around it. It can be temporarily disabled and bypassed with some effort, but they're not really meant to work that way.

    3 replies

    D Fosse
    D Fosse
    Braniac
    August 17, 2016

    The Pantone swatch is defined as Lab 70/-40/63. That's the reference.

    Illustrator is showing sRGB values. Photoshop is showing Adobe RGB values. That explains the big differences.

    But then you have some small discrepancies, a value up or down in some places. This can for instance happen if you sample from a jpeg, which compresses color as well as luminance, so you often end up with slightly different values.

    It could also be rounding errors in a round trip between RGB and CMYK. The color picker readout, in any other mode than what the file is in, is a recalculation based on what your current working spaces are set to. CMYK is always a wild card - all CMYK profiles are based on actual press/paper/ink combinations, and compensations for all sorts of things are built into the profiles. CMYK to CMYK round trips will always change values when returning to the original profile.

    It is also important to realize that gamut limitations and gamut clipping can play a part in this. This particular color is just outside gamut for US Web Coated v2 (SWOP), which is very likely your working CMYK (assuming you haven't changed anything in your color settings). So in a round trip, that would clip the color and thus change the values.

    Hex is just a different notation for RGB. It has no significance whatsoever beyond that.

    HSL/HSB can safely be ignored. That's a hybrid model with no firm and unequivocal basis, and it's relative to virtually anything.

    ---

    Bottom line. Lab 70/-40/63 translates to

    • Adobe RGB 142-188-57, or hex 8ebc39
    • sRGB 119-189-35, or hex 77bd23

    These are the correct values.

    D Fosse
    D Fosse
    Braniac
    August 17, 2016

    Wait a minute...I notice the Lab values for the Pantone swatch are two point decimal precision, not whole numbers. In other words this is higher than 8 bit precision - and if your file is 8 bit, there's bound to be rounding errors.

    Can you try with 16 bit files and recheck?

    But again, note that the big differences are due to one app being set to sRGB and the other Adobe RGB.

    D
    deelandAuthor
    Inspiring
    August 15, 2016

    Let's just clear something up: I'm asking for an answer based on data. I've come to the table with data: assumptions are not a valid response.

    These numerical discrepancies occur if colour management is turned on or off.

    Also, here is a JPEG of the table, to keep things clearer.

    It would be great to hear from an Adobe engineer of some sort.

    D Fosse
    D Fosse
    Braniac
    August 16, 2016

    This has nothing to do with colour management.

    It has, and in a very basic way: Color values are relative to color space.

    The same color will be represented by different values in different color spaces. Inversely, the same numbers will produce visually different colors in different color spaces.

    Naked numbers do not represent specific colors, other than what they arbitrarily end up as on your particular display.

    Hex is just that: naked numbers with no reference.

      D
      deelandAuthor
      Inspiring
      August 16, 2016

      D Fosse

      I've drawn up a new table, with just two colour sources:

      One is pantone.com (chosen, because, well, it's Pantone. A reputable source, one would think, yes?)

      The other is color.adobe.com  (chosen, as Adobe is the source of the numerical inconsistencies)

      So, one can safely say, using these sources, we are dealing with pure data. Nothing to do with colour management, colour spaces, colour profiles. Indeed, no documents are actually open in an application. Just numbers. No colour picking, just dialling in numbers, and noting the results of other areas of the interface.

      Would you not expect the values to be the same? As in numerical descriptions of colour, as in differing descriptions of colour spaces/modes such as CMYK, RGB, # HEX, HTML.

      Granted, the actual green "looks" the same, but the numbers differ. Personally, I don't care. I've been in the industry for many years, and I know what I'm doing. I get the results I expect to get. However, this came up again recently, when a studio quizzed me about which app was to be trusted with the correct numbers. They too were confused to see differing numerical results. My advice was to be consistent, and use the same app throughout, for dealing with vector artwork from print to web workflow. That way, you can always refer back, if a witch hunt occurs. I didn't think much of it immediately, but went back later to check. Differing numerical numbers. I also remember this issue from many years ago (around CS3 days), when a client gave me a print brand guide. Colour values dictated in the guide did not match the software. I had a hell of a time convincing the client the result would be fine in the end. So, after so many years passing, I still see these odd discrepancies in different software.

      Even if software engineers could never make these values consistent, and there was a fundamental reason behind it, I would like to know what that is. Wouldn't you?

      PS: I've dropped references to the myPantone app (it's no longer free, and is quite an expensive subscription).

      Mylenium
      Mylenium
      Braniac
      August 15, 2016

      There are no inconsistencies beyond a) the possible lack of color management and b) inaccuracies and quantization errors when e.g. trying to convert a Pantone color directly to a web hex code and c) the inability to render some colors in different gamuts/ color spaces. Sorry, but you've put in a lot of work for nothing. There really is not much sense in comparing actual screen values to an abstract web service or app that assume idealized color profiles or may use simplistic formulas just as you cannot expect local values to be the same if your color management is not set up accordingly.

      Mylenium

      D
      deelandAuthor
      Inspiring
      August 15, 2016

      The final row didn't paste:

      https://color.adobe.com

      89 -77 84

      65 0 100 0

      89 255 0

      99 100 100

      59FF00

      This has nothing to do with colour management. Yes, I do know what that entails.

      No conversions of a Pantone, just a value lookup within the interface of the software(s).

      Nothing to do with rendering in colour spaces. Purely lookup states.

      I disagree with your stance: "There really is not much sense in comparing actual screen values to an abstract web service or app that assume idealized color profiles or may use simplistic formulas just as you cannot expect local values to be the same if your color management is not set up accordingly."

      There is a perfectly reasonable expectation for numerical consistency across Adobe applications. A consistent colour engine, if you like.

      Finally, don't be sorry for me. I enjoy this sort of thing.

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