Olympus Camedia C-750 Ultra Zoom Reference Manual page 115

During shooting and playback, you can display a histogram showing the
brightness and contrast of your subject in the monitor or viewfinder
Checking the histogram enables precise exposure control when taking
pictures.
During playback, you can display a histogram showing the brightness and
contrast of recorded pictures.
The histogram display can be set separately for shooting mode and playback
mode.
Ex: When a histogram is displayed in P mode
When the image is bright
The part indicated in green
in the histogram shows the
luminance distribution within
the AF target mark.
When the image is dark
{,Q
x
o
C
much of the right
frame, the image
will appear mostly
white.
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