Denon DVD-9000 Operating Lnstructions page 48

E:
(1) On the gamma correction display, the horizontal axis indicates the brightness
level of the image as recorded on the disc, while the vertical axis indicates the
brightness level of the image when output from the set.
(2) When a bright point on the disc side is adjusted to "dark" on the output side as
shown in the diagram at the right, normally the details of bright sections that
are hard to see become easier to see.
(3) When a bright point on the disc side is adjusted to "bright" on the output side
as shown in the diagram at the right, normally the details of dark sections that
are hard to see become clearer.