If I understand correctly the ImageDataGenerator class is a generator and returns batches of images when called, but what I don't seem to understand is:
The documentation says:
- featurewise_center: Boolean. Set input mean to 0 over the dataset, feature-wise.
- featurewise_std_normalization: Boolean. Divide inputs by std of the dataset, feature-wise.
How can you set mean to 0 over entire dataset when you have only a batch of images at any given time? and same for normalization.