Right now the resize function does not preserve the image aspect ratio and there is no way to do that right now. The image crate has methods to achieve this, like resize, resize_to_fill, resize_exact, thumbnail and thumbnail_exact.

This is a big feature missing, and I would love to have methods similar to these listed. I love ril because compared to the image crate, it already includes all the dependencies and the API is amazing, so adding these methods will be a really good addition!