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.

The Toolbar

The Up and Down Arrows will change the zoom of the X axis of the display. The Y axis always scaled so that the data fill the window.
The checkerboard button toggles between taking data from the image display (low resolution) and taking data from the file (high resolution). This works for all of the line drawing modes but not for histogram mode, where data always come from the image display.
The lock button will prevent the graph from being redraw even if the image point or other settings change. Thus, one can open several graph windows and display different positions in them.
The export to file button will allow you to save the currently graphed values to a text file. Enter the name of the file after pushing the button. The file will contain two columns of values: first, the X-coordinate of the graph, which will correspond to position along a selected axis or along a contour; second, the graphed value, which will be based on the loaded image data or the data in the file, depending on the state of the high-resolution button. A subset of values constrained by a rubber band can be saved, but all computed values will be saved, not just the ones that fit in the graph display. The X-coordinate is not adjusted for binning if data are loaded binned.
The selector box lets you pick which axis to display, or whether to graph along a contour or show a histogram of values. The graph along a contour is based on pixel values measured at 1-pixel intervals along the contour.
The Width spin box allows you to set a width to average over along the line being graphed. In the simplest case, the width represents the number of parallel lines being averaged. Only pixels in the X/Y plane will be averaged, so the function is not available when graphing in Z. Also, when graphing along a contour, pixels in the X/Y plane perpendicular to the contour are selected for averaging.
The number after the width box shows the Mean of the values being displayed. The one exception to this is histogram mode, where byte values from the image display are still used for the histogram when high resolution display is selected. In this case, the mean value will be scaled so that it represents the corresponding value from the image file. This value will be close to correct as long as intensities were not truncated when the data were read in.

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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