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
- 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
- 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 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
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.
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).
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.