Glass Film
Apply decorative window film to your window glass. Use the non-adhesive type, which comes in a variety of attractive textures and designs. Decorative film will allow light to pass through the glass, but will also provide you with a level of privacy. Choose a simple pattern or texture that resembles etched glass, which won't detract from the natural beauty of your window design. The materials can be cut to fit your window's exact size and shape.
Sheers
Create pleated sheers for your elliptical window, with white, beige or light blue see-through polyester fabric. Attach the panels to a flexible curtain rod. Or, hang two long panels of white embroidered sheer fabric on a flexible rod for a simple window treatment that will show off the arched window shape while allowing the flow of light into the room. Create slim tie-backs out of matching embroidered fabric, to hold the curtains back during daytime hours.
Roman Shades
Create your own roman shades with an arched top for your elliptical window, or have them custom made. Use a flexible curtain rod to create the shape of an ellipse to anchor your shades at the top of the arch. Choose a flat roman design, and make them out of light colored fabric that overpower the beauty of your windows. Consider a pale blue silk fabric or a romantic toile chintz, with a white background and light blue print. Create the shades so they will gather at the base of the arch when they're raised.
Honeycombs and Blockers
Choose honeycomb shades, which can be cut to the exact shape of your elliptical window. These shades are made out of opaque cells that trap air. They will help insulate your home in summer and winter, allow the flow of light and provide privacy. Choose two separate honeycomb blinds, one for the elliptical window and another for the bottom portion of your window, or choose a single honeycomb shade for the whole window. Another possibility is to place a white window blocker inside of the elliptical window space. Block inserts will enhance the window space, but they will also prevent any light from coming through the glass.