RGB Function May Map to Incorrect Color

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Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements. When you use an application method or property that accepts a color specification value, use a number that represents an RGB color value. An RGB color value specifies the relative intensity of the red, green, and blue colors that cause a specific color to be displayed.

The following steps assume that you created a Visual Basic module that contains the following code

   Sub ChangeRGB()

       ActiveSheet.Rectangles(1).Select
       With Selection.Interior
           .Pattern = xlSolid
           .Color = RGB([B1].Value, [B2].Value, [B3].Value)
       End With

   End Sub
				

and that you created a worksheet that contains the following values:

   A1: Red     B1:       C1:       D1:
   A2: Green   B2:       C2:       D2:
   A3: Blue    B3:       C3:       D3:
   A4:         B4:       C4:       D4:
   A5:         B5:       C5:       D5:
				

To use the sample macro, follow these steps:

1. On the View menu, point to Toolbars, and then click Drawing.
2. Click the Rectangle tool on the Drawing toolbar. Click cell C1 and drag the pointer from cell C1 to cell D5 to draw a rectangle.
3. On the Tools menu, click Options. Then, click the Color tab.
4. In the Standard colors group, click the first color in the second row (the red color).
5. Click Modify. Then, click the Custom tab. In the Red box, change the value to 65. Click OK.
   
   Notice that the color is dark red.
6. Click Modify. Then, click the Custom tab. Change the value of the Red box to 64. Click OK.
   
   Notice that the color is a little darker or duller than before.
7. Click Reset. Then, click OK to close the Options dialog box.
8. On Sheet1, enter the value 65 in cell B1.
9. On the Tools menu, point to Macro, and then click Macros. Click ChangeRGB, and then click Run.
   
   Note that the color of the rectangle is dark red.
10. Change the value in cell B1 to 64.
11. On the Tools menu, point to Macro, and then click Macros. Click ChangeRGB, and then click Run.
    
    Note that the color of the rectangle is black.

NOTE: You can work around this problem in Microsoft Excel. The ShapeRange objects collection allows greater flexibility when you change colors in code. Instead of using Selection.Interior.Color = RGB(x,y,z), you can use Selection.ShapeRange.Fill.ForeColor.RGB = RGB(x,y,z).