tracer
------

What it does:  Creates 'click files', data points obtained by tracing images
               in FITS files.  Attempts to do a better job than euv-imtool's
               tracing capabilities by supporting fixed-distance clicks, point
               deletion, and 'chaining' of points to make multiple groups of
               connected points to more clearly illustrate the geometry of the
               image being traced.

Controls:      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:
                 1) Number of 'bins' into which the colors can be quantized.
                 2) Color offset, enables the user to make small adjustments
                    to the minimum and maximum values for each bin.
                 3 and 4) 'Influence' of the quantized image and the original
                    image, respectively.  Effectively, it is the ratio of
                    quantized image to original image that is shown in the
                    view window.  This allows for the image to be 'partially
                    quantized'
               
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.  


        
