reprocessing steps for images before training classification models
I assume you talking about preprocessing instead reprocessing.

Divided the image with 255.0 value is a normalization technic called min/max normalization. Like the other normalization methods, min/max normalization used to improve performance of CNN's.

Image process methods like gaussian blur, average filter etc. are using to remove the noise as you said. You might want to denoise your input image to avoid performance losses.

Using purpose of morphology methods are depends on what is your data and what do you want to do your dataset with these methods. You can refer this link to see the methods that cv2 shared with code snippets.


Greetings