Overview:
tracer is used to manually "trace" interesting features found in
FITS files. This is done by clicking points around these features and
having the program record the points that have been marked. While
euv_imtool can do this, tracer tries
to offer a more sophisticated approach, allowing for enforcement of a
fixed distance between "clicks", point deletion, and chaining of points
to establish some sort of grouping to the connected points in order to
make the tracing process easier and to provide more enlightening results.
How to use:
The left mouse button on the main window will place a point,
connecting it to the previous point with a line by default. The
middle mouse button breaks the chain, making the next point
placed the beginning of the next chain. Note that this also
suspends the fixed-distance enforcement. The right mouse button
deletes the nearest point, breaking chains if necessary.
The CT sliders near the bottom change color table information;
'minimum' is the blackpoint, 'maximum' is the white point, and
'gamma' sets the gamma value. The HL sliders affect the
behavior of the marginally useful highlighting function which
highlights points in the image similar in intensity to the one
most recently clicked. Subtract background does background
subtraction similar to bgsub, though no changes
are permanently
saved. The 4 sliders to the right of the window are used to
quantize the color values seen in the main window. This is
useful on occasion as it gives distinct boundaries from one
color region to the next. From left to right, the functions of
the sliders are:
Notes:
The click files output by tracer are similar to those put out
by euv_imtool. The first three columns,
which store minL, mlt, and magnetic longitude data, are identical, while
the additional values are used only by tracer and plotter. For simple uses, however, programs that
could read euv-imtool's click files
should be able to read in those made by tracer as well.