			   FITSImageBrowser

This directory contains a demostration of a basic browser for
exploring astronomical images in FITS format.  It can be run as either
an applet within the JDK appletviewer or as a standalone application.
To run them, you need have JDK 1.0.2 or higher
(http://java.sun.com/products/JDK) already installed.  You also need
to properly set your CLASSPATH to include the Horizon library of
classes.  See Horizon/examples/README for details.

To run this demo as a standalone application, one usually types
something like,

   java apps.FITSDemo.FITSImageBrowser

in this directory.  Alternatively, you could run the demo as an applet
within the appletviewer that comes with Sun's JDK.  To start as an
applet, type:

   appletviewer FITSImageBrowser.html

You can also run this demo from our Web site at 
http://imagelib.ncsa.uiuc.edu/imagelib/Horizon/examples/index.html.

The applet comes up initially ready to access a 3D images cube of
hydrogen cyanide (HCN) gas from the expanding envelope of the evolved
star, IRC+10216.  The third axis in the cube represents velocity; each
slice along this access shows gas moving away from us or toward us at
a different velecity.  Pressing the "Load" button will cause the data
to be loaded and displayed.  Other FITS images can be viewed, by
either selecting another image from the applets choice menu or by
entering the URL to a valid FITS file in the text field.  (To edit the
text field, choose "Enter URL above" from the choice menu.)    

A number of controls are available from the viewer's menu bar.  These
include:  

  Menu Selection:       Action:
  ----------------------------------------------------------------
  "Data=>Slice...":     pops up a window for selecting 2-d slices 
                        from the cube; the slice can be parallel to
			any side of the cube.  

  "Data=>Range...":     pops up the Transfer Function panel which
			allows one to restrict the data value range 
			that gets mapped into viewable colors.

  "Data=>Palletts":     pops up a choice of five color maps that can
			be used to visualize the data

  "Data=>Metadata":     pops up a window displaying in hierarchical 
			form the Metadata associated with this data.

  "Control=>Zoom":      pops up a zoom control window

  "Control=>Selections":  
                        pops up a window for editing data selections

  "Control=>Free Position" 
		        this allows the positions associated with
		        fractional pixels to be displayed.  

  "Control=>Position On Select"
                        When this is turned off, the postions are
                        updated whenever the mouse moves over the
                        image.  When turned on, the positions are
                        displayed only on the last selected voxel.  





