VI et epth  ->  depth

depth      integer      returns the current screen depth in bits.

Returns the current screen depth of the main screen. 

The screen depth is expressed as the number of bits used to store the colour data:
        Bits     Number of colours/grays *
         1              Black & White
         2              4
         4              16
         8              256
        16             Thousands
        24              Millions

                * as listed with the Monitors control panel

If this function returns zero, an error occured while determining the screen depth. Any other value is the screen depth.

See the example with the VI et epth function.