Pentax K-m/K2000 Operating Manual page 29

The shape and the distribution of the histogram before and after shooting
tells you whether the exposure level and contrast are correct or not, and
lets you decide if you need to use EV compensation and take a picture
again.
1 Adjusting the Exposure (p.104)
Understanding Brightness
When the brightness is correct and there are no overly light or dark areas,
the graph peaks in the middle. If the image is too dark, the peak is on the
left side, and if it is too bright, the peak is on the right side.
Dark image
When the image is too dark, the part to the left is cut off (dark portions with
no detail) and when the image is too bright, the part to the right is cut off
(bright portions with no detail).
Bright portions blink red on the monitor and dark portions blink yellow
when [Bright/Dark area] is On.
1 Playing Back Images (p.72)
1 Setting the Display for Instant Review (p.222)
Understanding Color Balance
Distribution of color intensity is displayed for each color in the RGB
histogram. The right side of the graphs look similar for images that have
White Balance adjusted well. If only one color is lopsided to the left, that
color is too intense.
1 Setting the White Balance (p.159)
Image with few bright
or dark areas
Bright image
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