how does Keras flow_from_directory affect computer storage?
By default, ImageDataGenerator does data augmentation on the fly and does not store the augmented images anywhere. As you mention, doing so would require too much space. So you should only worry about having enough RAM to fit a certain number of augmented batches, not the whole dataset.
I'm trying to figure out the minimum amount of room I will need to train neural networks on my machine. Often times (image) data sets are relatively small in their raw forms, but when we transform them (in keras w/ flow_from_dir) we augment the images and kind of multiply the size of the data set to our desire. 
My question is: how does flow_from_directory work with storing the augmented images? If I don't specify that the images need to be stored (parameter of the class) does keras augment the image, train with it and discard it or does it save it for a period of time, weighing down my computer until training is over?
Also, would those images be in persistent memory or RAM? Thank you in  advance.