  Incremental Learning (IL) is useful when artificial systems need to deal with
streams of data and do not have access to all data at all times. The most
challenging setting requires a constant complexity of the deep model and an
incremental model update without access to a bounded memory of past data. Then,
the representations of past classes are strongly affected by catastrophic
forgetting. To mitigate its negative effect, an adapted fine tuning which
includes knowledge distillation is usually deployed. We propose a different
approach based on a vanilla fine tuning backbone. It leverages initial
classifier weights which provide a strong representation of past classes
because they are trained with all class data. However, the magnitude of
classifiers learned in different states varies and normalization is needed for
a fair handling of all classes. Normalization is performed by standardizing the
initial classifier weights, which are assumed to be normally distributed. In
addition, a calibration of prediction scores is done by using state level
statistics to further improve classification fairness. We conduct a thorough
evaluation with four public datasets in a memoryless incremental learning
setting. Results show that our method outperforms existing techniques by a
large margin for large-scale datasets.

Computer Vision and Pattern Recognition