How to get started preforming inference with outside images

My model does a pretty good making inferences on images provided in the dataset that I used to train and test the model, but I was wondering if it is possible to get a prediction using an outside image. If so, I was hoping someone can get me started in the right direction on how to load and properly prepare the image. I am currently working with the MNIST dataset by the way,

My notebook if interested:
https://colab.research.google.com/drive/16RFi_fERIyHMpiNXlGJb01faUsJWrkot