python - How to rescale images from [0,255] to [-1,1] with ImageDataGenerator?

Question

I'm using ImageDataGenerator with flow_from_dataframe to load a dataset.

ImageDataGenerator allows you to specify a rescaling factor like this

datagen = ImageDataGenerator(rescale=1./255)

But what if I want to rescale my images in the range [-1,1]? I should do a subtraction followed by a division

images -= 128.0
images /= 128.0

How can I do these two operations in the rescale of ImageDataGenerator?

question from:https://stackoverflow.com/questions/65928036/how-to-rescale-images-from-0-255-to-1-1-with-imagedatagenerator

Answer 1

try using rescale=1/127.5-1 or you can use pre defined processor functions such as

preprocessing_function=tf.keras.applications.mobilenet.preprocess_input