Hi @coin,
A standard normalization technique like Z-scoring/standard-scaling pixel values within image channels, if applied once to an image as part of preprocessing, is not considered augmentation. In general, preprocessing techniques to normalize an image that is applied once is not considered augmentation.
From the competition rules:
“Augmenting” images refers to applying a transformation to an image to generate a new image, such as the manner in which the query set images were derived from the reference set images.
Please refer to this previous answer for more general clarification about when augmentation is allowed or not.