% @(#)extractrac.hlq	17.1.1.2 (ESO-IPG) 02/25/02 17:46:19 
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%.COPYRIGHT  (c)  1990 European Southern Observatory
%.IDENT      extractrac.hlq
%.AUTHOR     KB, IPG/ESO
%.KEYWORDS   MIDAS, help files, EXTRACT/TRACE
%.PURPOSE    On-line help file for the command: EXTRACT/TRACE
%.VERSION    1.0  05-FEB-1990 : Creation, KB
%----------------------------------------------------------------
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SECTION./TRAC
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EXTRACT/TRACE						02-FEB-2002  KB
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EXTRACT/TRACE [step] [frame] [plot_flag] [cut_option] [zw_option]
	extract a line from displayed image
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Purpose:  
          Extract interactively a line from a displayed image.
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Syntax:  
          EXTRACT/TRACE [step] [frame] [plot_flag] [cut_option] [zw_option]
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          step = stepsize along the traced line;
               defaulted to stepsize in x of displayed image
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          frame = name for result frame, defaulted to 'trace.bdf'.
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          plot_flag = DRAW, PLOT or NONE, defaulted to DRAW;
               if set to DRAW, a plot of the extracted column is displayed in
               the overlay channel each time the ENTER button is pushed
               if set to PLOT, a plot of the extracted column is displayed on
               the graphics terminal (graphics window) each time the ENTER
               button is pushed
\ap\pa
          cut_option = C(UT) or N(OCUT) , defaulted to N;
               for C only extract line bound by the two cursors; for N extract
               complete line through cursors
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          zw_option = zoom_window_flag,zoom;
              zoom_window_flag = W for zoom_window, N for none,
              zoom = initial zoom factor; defaulted to N,4;
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See also:
          EXTRACT/CTRACE, EXTRACT/RTRACE, EXTRACT/ROTATED
          VIEW/IMAGE, GET/CURSOR
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Note: 
             Use the mouse to move cursor #0 and the arrow keys of the 
	  keyboard to move cursor #1, to define a trace across the
	  currently displayed image. 
	  The trace is actually drawn only after pushing the Enter button
          (left button on the mouse).
             To extract the chosen line and exit, press the EXIT button 
	  (the button to the right of the ENTER button).
          A slice of the displayed frame along this trace line will be 
	  extracted from the displayed frame and stored into the new frame
          (e.g. trace.bdf). The start/end pixels of the original frame where
	  the trace was extracted are saved in int. descr. START_END_TRACEPIX.
             With the zoom window option you first select a subwindow in the
          main display window. Then move the mouse into the zoom window
          together with the arrow keys for cursor 1 choose the trace. 
	  Push Enter to extract the trace and draw the full trace vector
	  in the main display window. Press Exit to go back to the main
	  window and choose another subwindow there or press Exit to leave
	  the command.
             All the additional functionality which comes with the zoom
	  window option (see e.g. VIEW/IMAGE) is also available.
             The parameter 'frame' may be set to "+" also, which means that 
	  no frame is extracted (only useful with plot_flag = DRAW or PLOT).
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Examples:
\ex
          EXTRACT/TRACE ? gato
            Extract 1-dim frame `gato.bdf' from displayed frame (complete line
            passing through both cursors) and show the profile, each time
            the ENTER button is pressed.
\xe\ex
          EXTRACT/TRACE 1.05 ? ? C
            Extract 1-dim frame `trace.bdf' from displayed frame (only the
            line segment between the two cursors), use stepsize = 1.05
            when extracting pixels along the line.
\xe\ex
          EXTRACT/TRACE ? mosca plot ? w
            Extract 1-dim frame `mosca.bdf' from displayed frame. Choose the
            trace points in the zoom window and plot the profile in the
            graphics window each time you press Enter (in the zoom window).
            If no graphics and/or zoom window exist, they are created with
            default sizes.
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