A Unified Framework for Image-Derived Invariants

# We propose a general framework for computing invariant features from images. The proposed approach is based on a simple concept of basis ex# pansion. It is widely applicable to many popular basis representations# suchas wavelets# short#time Fourier transform# and splines. 1 Introduction Image features and shape descriptors that capture the essential traits of an object and are insensitive to environmental changes are ideal for recognition. The search for invariants #e.g.# algebraic and projectiveinvariants# is a classical problem in mathematics dating back to the 18th century. The need for invariant image descriptors has long been recognized in computer vision #3#6#. Invariant features form a compact# intrinsic description of an object# and can be used to design recognition algorithms that are potentially more e#cient than# say# the aspect#based approaches. Hence# it was even argued that object recognition is the search for invariants #6#. Invariant features can be designed based o..