User Manual

Table Of Contents
Histogram
The Histogram Viewer is an analysis node that can be used to identify problems with the
contrast and dynamic range in an image. The graph shows the frequency distribution of colors
in the image, including out-of-range colors in floating-point images. The horizontal axis shows
the colors from shadows to highlights. The vertical axis shows the number of pixels in the image
that occur at each level.
The Histogram Viewer will also display gradient information. You can use the From Image and
Perturb modifiers to output gradients. If you need to see the gradient represented in a
histogram, drag the modifier’s title bar into the viewer.
The Histogram Viewer type for evaluating
the contrast and color cast in an image.
3D Histogram
The more advanced 3D Histogram Viewer shows the color distribution in an image within a 3D
cube. One advantage to a 3D Histogram is that it can accurately represent the out-of-range
colors commonly found in floating-point and high-dynamic-range images. It can also be used to
look at vector images like position, normal, velocity, and so on.
The 3D Histogram Viewer type for
evaluating out-of-range colors.
To rotate within a 3D Histogram, do one of the following:
Hold down the Option key, and drag left or right using the middle mouse button.
Hold down the middle and right mouse buttons while dragging.
Chapter – 58 Using Viewers 1143