Help on Digital Color Meter

Discussion in 'Design and Graphics' started by lordthistle, Jun 9, 2010.

  1. lordthistle macrumors 6502

    Feb 29, 2008
    I need to create a new Keynote theme based on a PDF file. In other words, I need to re-create the text layout and the colors used in the PDF file.

    The problem: I am not able to get the correct colors in the keynote file.

    1) I need to insert in the keynote file a row split in two parts, each one being a different shade of green.

    2) I sampled the colors in the PDF file using the OS X app Digital Color Meter (DCM).

    3) However, when I insert the RGB triplet in Keynote, the displayed color is (much) different from the PDF one:


    The correct color is the darker green (small box). The lighter green is what Keynote shows when I pass the RGB triplet of the small box.

    4) In fact, if I use the Digital Color Meter on the wrong color shown by keynote, the read value does not correspond to the RGB triplet I inserted. The DCM, however, still reads the same triplet as in the PDF file from the small darker box.

    Are you aware of a solution to this problem?

  2. Kwill macrumors 68000


    Mar 10, 2003
    Has to do with color management

    RGB values are not as absolute as they appear to be. Each application (and/or file) can use a different base color for each of the three hues.

    As a comparison, imagine specifying CMYK percentages to build a color. We can expect that if standard process colors are used and that press gain falls within specifications on the appropriate coated paper, colors will be very close. Run the same percentages on newsprint or, worse yet, switch the cyan with reflex blue and those percentages yield wildly different results.

    Not only can identical RGB values be interpreted differently by various applications, there are actually several different types of RGB. Applications must answer: 'Which red, blue and green and how bright?' This explanation could get very deep and lengthy so I'll just volley a theory with a rather primitive solution.

    Likely the Adobe Acrobat file includes an embedded color profile. If not, then the default color management settings (if enabled) are applying a profile. Either way, the definition of "RGB" differs from the Keynote default. You need to get the swatch to match the Keynote color space before taking measurements.

    The simplest way I can suggest is to take a screenshot of the Acrobat image and drag/import it into Keynote. Then sample colors within Keynote. Alternatively, you may try importing the PDF into Keynote directly to sample colors.

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