Progressive image transmission allows an approximate image to be built up quickly and the details to be transmitted progressively through several passes over the image. This technique appears very useful for picture communication over slow channels. This paper presents a survey of progressive image transmission techniques including spatial domain, transform domain, and pyramid-structured approaches. Image coding techniques that are not currently used for progressive transmission, but that have this capability or can be modified to provide progressive transmission, are also identified. The main features, computational complexity, and typical performance are discussed for each technique. Among various approaches, there are always trade-offs between system complexity and performance. Which approach is most appropriate depends upon the application.