[GAN] #10 Move Image Normalization to a Separate Function: Create a Function for Image Normalization

[veeradi34]

Description: The normalization of images in the MNISTUbyteDataset class is done inline. This functionality should be encapsulated in a separate method for better readability and reuse.

Tasks:

Create a function normalize_image(image) that performs the normalization.
Update the getitem method to use this new function.