Parameter

Meaning

wParam

Specifies whether the window should be redrawn to reflect the image changes. Use 1 to redraw the window, or 0 not to redraw it.

lParam

The low order of the lParam parameter should contain the amount to change the contrast. The value should range between -1000 and 1000.

SUCCESS

Function was successful.

< 0

An error occurred. Refer to Return Codes.