Use multiple image input layer in deep learning network

Using the dataset that I have, I would like to train my network using multiple image input layer which has different resolution. How should I implement it in MATLAB (2018a)?

Ex: I have input image with the original resolution of 512x512, and now I would like to train the network with multiple input of 480x480, 512x512, and 640x640 using the same dataset.

[Krishna Bindumadhavan]

What is the input size of the Neural Network that you will be training? Did you consider resizing the images perhaps to this input size?