Blurry background in mobile devices

I am using the cherry framework and I am having a problem with my background image. The full-screen background image in my sites is looking blurry. The stranges part is this doesn't happen for all the pages, but most of them. Looking at the pages from a desktop at mobile view looks completely fine, but when I view it on a mobile device it is all messed up.
We tried media queries to solve the issue but had no luck.