How to replace a color with one I exactly want

Discussion in 'Photoshop' started by hzmonte, May 17, 2006.

  1. hzmonte

    hzmonte Guest

    Let's say my skin is too yellowish and I want to replace it with the
    more pinkish one of a young beautiful girl I find in another picture.
    How can I do it? Thx.
     
    hzmonte, May 17, 2006
    #1
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  2. hzmonte

    Mike Russell Guest

    Method 1) Measure a target RGB value, set up an eyedropper sample point on
    your final image, and then use curves to achieve your desired RGB value.
    Your adjustment will consist of adding red and/or removing green. You may
    get a better result by using an HSB target value, and matching the Hue and
    Saturation values.

    Method 2) Measure the RGB value as before, and use selective color to add
    magenta to red, or subtract green, until you reach the RGB or HSB value you
    want.

    Method 3) If you are on Windows, you can use Curvemeister's color pinning
    feature. This is an automated version of Method 1, where Hue and Saturation
    are set to nominal skin values, and where the best color space may be easily
    chosen.
     
    Mike Russell, May 17, 2006
    #2
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  3. hzmonte

    hzmonte Guest

    Method 2) Measure the RGB value as before, and use selective color to add magenta to red, or subtract green, until you reach the RGB or HSB value you want.
    According to Color Picker, the pinkish color I want has these values: H
    20 S 37 B 92 L 77 a 19 b 23 R 234 G 177 B 148 #EAB194.
    But Selective Color provides ways to only increase or decrease a color
    by a certain percentage.
    So how do I translate those absolute values into the %s?
     
    hzmonte, May 17, 2006
    #3
  4. hzmonte

    Mike Russell Guest

    The HSB color model will probably the most useful for this, and modifying
    the amount of magenta, green, and cyan in red will allow you to zero in on
    the Hue and Saturation value you want.

    Place an info "eyedropper" on the original yellowish skin tone, and set it
    to read HSB. Since your target color has more red in it, add magenta to
    red, or subtract green from red to get the desired Hue angle of 20 degrees.
    The saturation and brightness may also be changed by altering the amount of
    cyan in red.

    There are other methods than selective color. CMYK is a good color space
    for fine adjustment of skin tones with curves, since it offers fine control
    over magenta and yellow.

    If you're going to do this very often, consider using the pinning feature of
    Curvemeister, which automates the process of setting a skin tone to a
    desired Hue and Saturation value.
     
    Mike Russell, May 17, 2006
    #4
  5. hzmonte

    hzmonte Guest

    1. Correct me if I am wrong. I think the procedure would involve
    mapping the color of a particular pixel in my yellowish photo to the
    color of a particular pixel in a pinkish photo, and using it as a
    'baseline' to map the color of other pixels in (the selected area of)
    my yellowish photo relative to the selected pixel.
    2. Let's say I select a pixel in the pinkish photo and somehow measure
    its values: H 20 S 37 B 92 L 77 a 19 b 23 R 234 G 177 B 148 #EAB194.
    Now EXACTLY how do I select a pixel in the yellowish photo and map it
    to these particular values? And as I said, the Selective Color dialog
    box appears to allow one to add color by a percentage. But why would
    anybody adjust it by trial and error by sliding along the bars, adding
    red, subtracting green, and so on, if he knows the exact color values
    he wants? How come there is nothing in Photoshop that allows me to
    select a pixel and say 'I want the color of this pixel to be R 234 G
    177 B 148 and adjust all other pixels relative to this pixel'?
     
    hzmonte, May 24, 2006
    #5
  6. hzmonte

    Mike Russell Guest

    You've obviously put a lot of thought into analyzing the problem and coming
    up with a solution. This has the problem that it becomes hard for others to
    tap into your train of thought and come up with a suggestion.

    The process you describe is called "color pinning" in curvemeister. More
    generally, if you use curves or another method to match a particular color
    to a target value, the rest of the image will follow suit. This is a
    standard way to remove a color cast.
    Create an eyedropper sample point over the source color, and perform your
    adjustment until the numbers match your target values.
    This would be a desirable feature, and it is implemented in the Curvemeister
    plugin. Photoshop's sample values are read-only, so it is necessary to make
    the adjustment and observe the color samples manually.
     
    Mike Russell, May 25, 2006
    #6
  7. hzmonte

    hzmonte Guest

    ...perform your adjustment until the numbers match your target values.
    What numbers? Where can I see the "numbers"? My problem has been that
    I am not able to see any absolute values of the colors, as adjusted, in
    my target photo. For example, the Selective Color dialog box shows a
    few sliding bars and I can adjust the colors by sliding along the bars
    and it also shows 10%, 20%, etc next to the bars (I have no idea what
    those percentages mean - I mean, percentages of what?), but there is no
    absolute values that says "OK, now Red's number is now 234, Green's
    value is 177, etc" so that I know I get the individual color channel of
    the target photo match my desired value. Are the "234 177 148" what
    you mean by "numbers"? How do I know whether I have reached the
    desired values?
    What do you mean by "manually"? pixel by pixel?
     
    hzmonte, May 25, 2006
    #7
  8. hzmonte

    Mike Russell Guest

    Place an eyedropper sample value on the area whose color you wish to adjust.
    The sample tool is accessed by clicking and holding the mouse button. You
    can create up to four sample points whose values will show on the info
    palette.
    I agree that pixel by pixel would certainly be absurd, and if I have implied
    that you should do this, I apologize for my rudeness. Adjust the controls
    until you see the value you want in the info palette.
     
    Mike Russell, May 25, 2006
    #8
  9. hzmonte

    Mike Russell Guest

    In my last post "clicking and holding the mouse button" should have said
    "clicking and holding the mouse button on the eyedropper icon in the tool
    palette".
     
    Mike Russell, May 25, 2006
    #9
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