If your images are not in the same size, I recommend you use the Ninja Slider that is responsive to your screen or your specified slider frame size, and you can specify how to deal with different aspect ratios of the images by the style { background-size:contain;} or { background-size:cover;}. If you are good at CSS, you can also consider using background-position and background-size together. For details please read the tooltip popup from the aspectRatio link on the page Ninja Slider.