Nikon D300 User Manual page 56

RGB histogram – I like this feature since it allows me to
view not just a basic luminance (brightness) histogram like
some cameras, but all three color (chrominance) histograms
and a luminance histogram in one screen (see Figure 2-12).
The D300S stacks the four histograms all on the right side of
the screen, with the luminance on top (white histogram) and
the RGB color histograms underneath. The D300 displays the
RGB histograms on the right side and places the luminance
histogram under the small picture. Figure 2-12 shows the
D300S screen.
Figure 2-12. Display mode screens – RGB histogram option
Each color channel—red, green, and blue—is displayed with
its own small histogram. This is quite useful since it is
possible to overexpose, or "blow out", only one color
channel, as happens often with the red channel in my case.
The luminance (white) histogram is very similar to the green
channel histogram since green is the most common color
around.
Data – This setting will give you up to four additional image
data screens to scroll through.
56