"The year was 2009, the computer was an Archimedes and the language used to write this remarkable program? BBC BASIC!" Sorry to rain on your parade, but although it was 2009 and it was BBC BASIC, the machine was in fact a fast PC running BBC BASIC for Windows (and with most of the number-crunching done in embedded 32-bit assembler code). Nevertheless, I agree that it demonstrates the power of BBC BASIC even today, but not an obsolete computer like an Archimedes! The newest example of the Colour Recovery application is of the pilot episode of Are You Being Served?, to be shown on BBC2 on New Years Day: http://colourrecovery.wikispaces.com/Processed+programmes Richard.