Graph Window

The Graph Window will display a graph of image values along a line in the X, Y, or Z direction, or along a contour. These values can be based on either the bytes being displayed in 3dmod, or on the actual values in the image file. Values along the line or contour can be averaged across a swath of selected width. The window can also display a histogram of scaled pixel values. The Zap rubber band can be used to select subareas for display.

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Other Features

The Zap Window rubber band can be used to select a subset of a line or contour to graph or a subarea from which to generate a histogram. If there is more than one Zap window open, the area is controlled by the rubber band (if any) from the current or last active Zap window. When graphing on an axis, the current image point will be moved to fit within the bounds of the rubber band. When graphing along a contour, the intensities will be shown for the first section of the contour inside the rubber band.

The center of the X axis in the graph, shown by the red vertical line, is maintained at the current image point (when graphing along an axis), ot at the current model point (when graphing along a contour). This is not quite the case when using the rubber band with a graph along a contour where the current point is outside the rubber band. Here, the center point of the display is kept near the edge of the rubber band, but the current model point is not changed to match. For a histogram, the scaling of the axis is constrained so that it excludes values outside the range of 0-256. The red line marks the intensity of the current image point but it may not be at the center.

When data are read in from a byte file, scaling the values may result in a histogram with many empty bins interspersed with bins full of counts. To avoid this effect, read the data in without scaling, i.e., with minimum and maximum scaling values set to 0 and 255 (-s 0,255).

When data are read into the program as 16-bit integers instead of bytes, a histogram is generated by first scaling the integers to bytes based on the current setting of the Low and High sliders in the Information window. Changing these sliders will thus change the histogram.

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