I have selected “no scaling, original height and width” and it still is stretching the images

the easy slider was stretching my images if fit, I wanted them to be all the same size, so I changes them in photoshop to be all the same resolution and pixel dimensions…..
after doing this easy slider still stretches the images depending on if the image was taken in landscape or portrait, even though every image is now exactly the same size…
So I started using advanced slider….
Can I use easy slider and not have it stretch my images?
thanks
Nick