Determining the RGB Value of a Color

Neil uses colors a lot in his worksheets. He knows that he can generate a color based upon a numeric RGB value (and as explained in other ExcelTips issues). Neil would like to do the opposite—determine an RGB value. He wonders if there is a way to return (via function or macro) the RGB value of the color used to fill a cell.

Excel doesn't include a function to do this, but you can create your own user-defined function. The function you use depends on what you want to actually have returned to your worksheet. For instance, if you want to have the traditional six-character hex code for RGB colors returned, you would use the following very simple macro:

Function getRGB1(rcell) As String
    Dim sColor As String

    sColor = Right("000000" & Hex(rcell.Interior.Color), 6)
    getRGB1 = Right(sColor, 2) & Mid(sColor, 3, 2) & Left(sColor, 2)
End Function

This macro looks at the interior color for any cell you reference, puts the hex values for the color in the right order, and returns the string to Excel. To use the function you simply invoke it, in your worksheet, with a cell referenced in this manner:

=getRGB1(B4)

You may not want the traditional hex codes for the RGB colors, however. If you want to get the decimal values for each of the colors, then the following macro returns that:

Function getRGB2(rcell) As String
    Dim C As Long
    Dim R As Long
    Dim G As Long
    Dim B As Long

    C = rcell.Interior.Color
    R = C Mod 256
    G = C \ 256 Mod 256
    B = C \ 65536 Mod 256
    getRGB2 = "R=" & R & ", G=" & G & ", B=" & B
End Function

Invoked the same way as the getRGB1 macro, this version returns a string such as "R=255, G=204, B=0". You can also modify the macro even further so that it returns a single value, based upon a parameter you set:

Function getRGB3(rcell As Range, Optional opt As Integer) As Long
    Dim C As Long
    Dim R As Long
    Dim G As Long
    Dim B As Long

    C = rcell.Interior.Color
    R = C Mod 256
    G = C \ 256 Mod 256
    B = C \ 65536 Mod 256

    If opt = 1 Then
        getRGB3 = R
    ElseIf opt = 2 Then
        getRGB3 = G
    ElseIf opt = 3 Then
        getRGB3 = B
    Else
        getRGB3 = C
    End If
End Function

To use the macro, simply add a second parameter to the function used in your worksheet, specifying what you want:

=getRGB3(B4,1)

If the second parameter is 1, then the function returns just the red value. If you specify a second parameter of 2, then the green value is returned, and 3 returns the blue value. Any other value for the second parameter (or if you omit it entirely) returns the full decimal value of the interior color.

If you don't want to go the route of creating a macro, or if you want to determine colors in more than just your Excel worksheet, you might consider a third-party utility. One that looks interesting is Instant Eyedropper, which is free. You can find more information about it here:

http://instant-eyedropper.com

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (10179) applies to Microsoft Excel 97, 2000, 2002, and 2003. You can find a version of this tip for the ribbon interface of Excel (Excel 2007 and later) here: Determining the RGB Value of a Color.