This article gives a tutorial overview of essential components of scale-space theory --- a framework for multi-scale signal representation, which has been developed by the computer vision community to analyse and interpret real-world images by automatic methods. 1 The need for multi-scale representation of image data An inherent property of real-world objects is that they only exist as meaningful entities over In: Proc. CERN School of Computing, Egmond aan Zee, The Netherlands, 8--21 September, 1996. certain ranges of scale. A simple example is the concept of a branch of a tree, which makes sense only at a scale from, say, a few centimeters to at most a few meters, It is meaningless to discuss the tree concept at the nanometer or kilometer level. At those scales, it is more relevant to talk about the molecules that form the leaves of the tree, and the forest in which the tree grows, respectively. This fact, that objects in the world appear in different ways depending on the scale of ..
