Set the file background color of an image. When saving an image to PNG, this background color is transparently saved to the PNG file.

Set the file background color of an image. When saving an image to PNG, this background color is transparently saved to the PNG file. When the bkcolor parameter is null, the background color is removed from the image.

This overloaded version of the function with an array parameter is provided to allow passing null in the bkcolor parameter. This is similar to the original C/C++ function. Passing null as bkcolor parameter will unset the dib's previously set background color.