Abstract: A modularized classifier is provided which includes a plurality of class specific modules. Each module has a feature calculation section, and a correction section. The modules can be arranged in chains of modules where each chain is associated with a class. The first module in the chain receives raw input data and subsequent modules act on the features provided by the previous module. The correction section acts on the previously computed correction. Each chain is terminated by a probability density function evaluation module. The output of the evaluation module is combined with the correction value of the last module in the chain. This combined output is provided to a compare module that indicates the class of the raw input data.