preprocess_input() method in keras

Question

I am trying out sample keras code from the below keras documentation page, https://keras.io/applications/

What preprocess_input(x)

Answer 1

I found that preprocessing your data while yours is a too different dataset vs the pre_trained model/dataset, then it may harm your accuracy somehow. If you do transfer learning and freezing some layers from a pre_trained model/their weights, simply /255.0 your original dataset does the job just fine, at least for large 1/2 millions samples food dataset. Ideally you should know your std/mean of you dataset and use it instead of using std/mdean of the pre-trained model preprocess.

My 2 cents.

Steve