Blurry images

Hey,

I love the plugin I’ve had it for about a year. I recently added a couple of new images to the gallery and they are appearing blurry as if the resolution isn’t high enough, however when I click on them and they open in a new web page I can see that they are fine. Would you be able to offer any solutions to this? https://www.antheaandlyndon.com/photography

Thanks ??

https://www.ads-software.com/plugins/responsive-gallery-grid/