Abstract: A film slide projector has a rail which engages a carousel in a complementary manner, such that a surface of the rail contacts a surface of each film slide in the carousel. Misoriented film slides are moved by the surface of the rail to expose a portion of such misoriented film slides outside of respective slots of the carousel to indicate such misorientation. Film slides having a predetermined proper orientation are completely contained within respective slots. The predetermined proper orientation of each film slide is determined by a cut-out portion capable of engaging the rail. Alternatively, a carousel may have walls forming slots with a rectangular cross-sectional cylindrical element protruding from a wall to cause misoriented film slides positioned thereupon to have a respective portion thereof extending through a respective open aperture to indicate misorientation.

Abstract: A low bandwidth video teleconferencing system and method is disclosed. The video teleconferencing system employs novel data compression techniques by which continuous transmission of imagery at a rate of 9600 bits/second is possible. A sketch coder converts the grey scale image to be transmitted to a sketch or line drawing, which comprises an outline of the principal boundaries plus shading to represent depth. The bandwidth required for the data representing the sketch is then compressed by two-dimensional run length coding techniques which exploit interframe and interline redundancy as well as intraline redundancy to generate a binary transmission code. Other features are also provided.