The top-level of OBVIUS is implemented in Common Lisp, thus providing an interpreted, object-oriented programming environment. The low-level floating point operations are implemented in C for efficiency. A graphical user interface, based on menus and dialog boxes is also provided, in addition to the Lisp interpreter (listener). In the typical mode of interaction, the user types an expression to the lisp listener (or enters a command in a dialog box) and it returns a result. A picture of that result will then be automatically displayed in a window. Each window contains a circular stack of pictures. The user can cycle through this stack using mouse clicks with certain shift (``bucky'') key combinations. Commonly used operations such as histogram and zoom are also provided via mouse clicks.

The system provides a library of low-level image processing routines. Some examples of these are:

• arithmetic operations (add, multiply, lookup-table point operations, etc)
• image statistics (mean, variance, kurtosis, maximum, histograms etc)
• convolutions, Fourier transforms, Hilbert transforms
• geometric operations (crop, slice, rotate, flip-x, etc)
• comparisons (greater-than, etc)
• synthetic image generation
• matrix operations

OBVIUS currently runs on Sun and SGI workstations in Lucid v4.1 Common Lisp. For the Sun implementation, it also requires the LispView interface to OpenWindows/X, which is available free of charge on the X11 distribution tape.