Apple Aperture 2 - Manual (Page 360)

360 Part III Performing Image Adjustments
Understanding How to Read Histograms
The histogram is a graph that displays relative brightness in an image, from pure black to
pure white. The area under the graph represents all the pixels in the image. From left to
right, the histogram describes the range of dark pixels (shadows), gray pixels (midtones),
and bright pixels (highlights) in the image. The shape of the histogram graph depends on
the tonality of the scene and the exposure.
Evaluating Exposure
Histograms are good tools for evaluating exposure. For example, a series of peaks in
the darker side of the histogram often indicates an underexposed image that consists
mainly of dark pixels.
Pix
els incr
ease
Shadows Highlights Midtones
Brightness increases