#include <GDIPlus.au3>
#include <GUIConstantsEx.au3>
#include <ScreenCapture.au3>
#include <WinAPIHObj.au3>

Example()

Func Example()
    _GDIPlus_Startup() ;initialize GDI+
    Local Const $iWidth = 150, $iHeight = 150
    Local $iColor = 0
    Local $hHBmp = _ScreenCapture_Capture("", 0, @DesktopHeight - $iHeight, $iWidth, @DesktopHeight) ;create a GDI bitmap by capturing an area on desktop
    Local $hBitmap = _GDIPlus_BitmapCreateFromHBITMAP($hHBmp) ;convert GDI to GDI+ bitmap
    _WinAPI_DeleteObject($hHBmp) ;release GDI bitmap resource because not needed anymore
    Local $iR, $iG, $iB, $iGrey
    For $iY = 0 To $iHeight - 1
        For $iX = 0 To $iWidth - 1
            $iColor = _GDIPlus_BitmapGetPixel($hBitmap, $iX, $iY) ;get current pixel color
            $iR = BitShift(BitAND($iColor, 0x00FF0000), 16) ;extract red color channel
            $iG = BitShift(BitAND($iColor, 0x0000FF00), 8) ;extract green color channel
            $iB = BitAND($iColor, 0x000000FF) ;;extract blue color channel
            $iGrey = Hex(Int(($iR + $iG + $iB) / 3), 2) ;convert pixels to average greyscale color format
            _GDIPlus_BitmapSetPixel($hBitmap, $iX, $iY, "0xFF" & $iGrey & $iGrey & $iGrey) ;set greyscaled pixel
        Next
    Next
    Local $hGUI = GUICreate("GDI+ Example (" & @ScriptName & ")", $iWidth, $iHeight) ;create a test GUI
    GUISetState(@SW_SHOW)

    Local $hGraphics = _GDIPlus_GraphicsCreateFromHWND($hGUI) ;create a graphics object from a window handle
    _GDIPlus_GraphicsDrawImage($hGraphics, $hBitmap, 0, 0) ;copy negative bitmap to graphics object (GUI)

    Do
    Until GUIGetMsg() = $GUI_EVENT_CLOSE

    ;cleanup GDI+ resources
    _GDIPlus_GraphicsDispose($hGraphics)
    _GDIPlus_Shutdown()
    GUIDelete($hGUI)
EndFunc   ;==>Example