New images added to this repository should have a clean background, and size of either 224x224 pixels or 227x227 pixels. If you are not able to do so, or it takes too much time from you, just add them to a folder called "Images to classify" and we will take care of it.
If you can do that, to add new images, just add them to the folder with the corresponding format: LETTER_NUMBER.EXTENSION. Matlab accepts jpg, jpeg and png extensions.