In order to display a subsampled version of the image, the original image
should be displayed on the Main Drawing Window.
The current image can be reduced by using the Subsampling option.
This option gives a dialog box that contains a sliding button
to select the rate of subsampling [ 1 , 10 ].. A subsampling
rate of n means that every nth pixel of every nth row will be used in
displaying the image.
Click OK or Cancel
Then, the reduced image will be displayed on the Main Drawing Window.
The current subsampling rate will be shown on the title bar.
