# Add/Subtract Constant

Enter the positive or negative ConstantValue in the Greyscale Value To Add field you want to add to the grey value of each pixel in the greyscale input image. For input images of type Image24PlanarColor, enter the positive or negative values for Plane 0 (red), Plane 1 (green), and Plane 2 (blue). You must also choose whether you want the edit control to handle the Overflow Mode with the new values in the output image.