WELCOME TO THE IMAGE PROCESSING DEMO


   Image processing can improve the way an image 
   looks. Image-processed data, or a processed image
   helps you distinguish and recognize more subtle
   characteristics of the original image. 


   MENU OPTIONS
   ------------

   File Menu:
      Select "Quit" to exit the Image Processing 
      Demo and return to the IDL Demo main screen.

   About Menu:
      Select "About image processing" for information
      about the Image Processing Demo.


   FEATURES
   --------
      IDL offers several ways to process an image, 
      some of which are introduced below:

      o  Zooming
         Smaller sub-sections of large datasets can be
         manipulated. The image shown here is an 
         aerial view of New York City. A section of 
         lower Manhattan is enlarged using the REBIN 
         function on a subscripted section of the 
         original image array.

         To reposition the zooming area, click your 
         mouse on the area you would like to see more
         closely.  


      o  Fourier filtering
         IDL's Fast Fourier Transform (FFT) function
         can process vectors and 2D array in either
         forward or reverse.

         <<Filter width>> slider
          Selects the filter width. A higher filter 
          width gives the filtered image higher 
          resolution.


      o   Pixel scaling
          The BYTSCL (byte scale) command scales pixel
          values into the range of available colors.

          <<Minimum>> slider
          You can specify the minimum byte value 
          allowed in the reconstructed image.

          <<Maximum>> slider
          You can specify the maximum byte value 
          allowed in the reconstructed image.


      o   Histogram
          Histogram equalization can be used to
          change the visible contrast of an image.

          <<Minimum>> slider
          You can specify the minimum byte value 
          allowed in the reconstructed image.

          <<Maximum>> slider
          You can specify the maximum byte value 
          allowed in the reconstructed image.


 
      o   Edges
          The SOBEL function performs edge enhancement
          on an images.

          <<Smooth width>> slider
          Sets the width of the smoothing function.
          A higher width produces a reconstructed
          image with lower resolution.


      o    Convolution
           Convolutions may be performed on arrays of 
           1, 2, and 3 dimensions. This screen shows
           the effects of convolving an image with
           a kernel.

           Use your left mouse button to click on 
           the squares of the kernel grid, toggling 
           them on or off.

           <<CONVOLVE>> slider
           Computes and displays the convolved image.