WAVELET TOOL

The Wavelet tool is a widget application program that graphically 
demonstrates the image compression capabilities of Wavelet Transforms.

THE WAVELET TOOL DISPLAY

The Wavelet tool display screen includes the following elements:

- A set of buttons (actually pull-down menu widgets) at the top of the
  display controlling the program options.

- A 256x256 byte display of the uncompressed image.

- A 256x256 byte display of the compressed image.

- A visual display of the wavelet basis of both the original
  image and the compressed image.

- A graph showing the ratio between actual values in the wavelet
  basis (Y) and the percentage of compression (X) that would result if
  the Y value was used as the threshold for compression.	

- An optional 256x256 byte display window that displays the
  difference between the compressed and uncompressed images.


SELECTING AN IMAGE TO DISPLAY

To select an image to display, position the mouse cursor on the "File"
button. Press and hold the left mouse button and select "Load" from the
menu that appears. A list of the files contained in the 'images' subdirectory
of your distribution will be displayed: select an image to view by clicking
once on one of the items in the list.

Images displayed by the Wavelet tool must be located in the 'images' 
subdirectory, and must be listed in the file "data.doc" contained
in that directory. See below for more information about using the
Wavelet tool with your own images.


SELECTING A BASIS FOR THE WAVELET TRANSFORM

You can select the number of Daubechies wavelet filter coefficients
to be used in the wavelet transformation. Position the mouse cursor
on the "Options" button. Press and hold the left mouse button and
highlight "Coefficients;" this will cause a sub-menu of possible
coefficient values to appear to the right of the menu. Select a value
by highlighting the number of coefficients you wish to use. Note that
the number of coefficients currently selected is displayed in parentheses
next to the word "Coefficients."


COMPRESSING THE IMAGE

You can select a compression percentage in one of three ways:

1) Click and drag the "Percentage Compression" slider until it displays
   the desired value.
2) Position the mouse cursor in the "% compression" graph and click
   the left mouse button.
3) Use the mouse to select the number field directly above the compression
   slider, type the desired number, and press Return.

When you have selected a new compression percentage, the display of the
wavelet bases will be updated to reflect the new compression. Clicking on
the "Compress" button will actually compress and display the image.


VIEWING THE DIFFERENCES BETWEEN THE ORIGINAL AND COMPRESSED IMAGES

To view the difference between the original and compressed images,
position the mouse cursor on the "Options" button, then press and hold
the left mouse button to select "Show image differences." A floating
graphics window will appear and display the byte information that was
"left out" of the compressed image.


SAVING THE COMPRESSED IMAGE	

You can save the compressed image into a file containing a 256x256
byte array by positioning the mouse cursor on the "File" button and
selecting "Save." A standard file-creation dialog will appear, allowing
you to name and save the image file.


THE TOOLS MENU

Positioning the mouse cursor on the "Tools" button and pressing the
left mouse button allows you to start three additional widget applications:

1) XLOADCT allows you to select the color table to use.
2) XPALETTE allows you to interactively specify the contents of the
   current color table.
3) XMANTOOL allows you to control the widget applications that are
   currently running.


USING THE WAVELET TOOL WITH YOUR OWN IMAGES

To use your own image with the WaveletTool, place it in the
'images' subdirectory of your IDL distribution.  Then edit the
'data.doc' file found there by adding the name of your image
and its size.  Your image will then appear as a input choice
when "Load" is selected.