The gallery container is changing its dimensions depending on the size of the browser.
If you use the Slideshow gallery, you can choose from two different Image Scaling: Fill or Fit.
- Fill scales image to completely fill slider container (recommended for landscape images)
- Fit scales image to fit the container (recommended for portrait images)
Here’s a visual to walk you through this process: http://pixelgrade.com/demos/assets/slider-image-scaling.png
That being said, there’s no specific aspect ratio or resolution for the images that you use to make sure everything looks spotless in the gallery. Our recommendation is that you should use the Fit option because it won’t cut the edges of the image, even when you resize the browser or you see the gallery on different devices (tablets, computer, mobile phone).