Site images flicker when loading on mobile Safari

Here's the site: http://www.jonduenas.com/portfolio-1/

This is my own photography portfolio site that I designed myself (I promise this isn't just shameless self promotion). When I load it on my own iPhone and iPad, the images all start flickering when they load, and what's worse is that sometimes when it's done, the images all look pixelated, like when you zoom into a page, but Safari hasn't rerendered it yet. I don't have this issue when loading on the desktop. Any help? Might it have something to do with the PHP I use to load the images into the page? I'm no good with PHP, so I had a friend write it for me a while ago. I don't recall it being an issue on older versions of iOS either. But it's been annoying me lately.

 

Haha thanks.

I tried turning on the debug console. It just said no errors, but everything still looked the same.