see data_exploration.py
https://keras.io/preprocessing/image/
https://stanford.edu/~shervine/blog/keras-how-to-generate-data-on-the-fly.html
https://blog.keras.io/building-powerful-image-classification-models-using-very-little-data.html
https://keras.io/applications/
https://gogul09.github.io/software/flower-recognition-deep-learning