I have a question regarding the image loading style as shown on <http://www.e-flux.com>. This website first loads an image of a certain pattern (randomly) before proceeding to display the actual image. My guess is that this is to have visually pleasing content before even having loaded the total website. 

I have looked at the source code and I saw that it had a class of "lazy is-loading". I think it has to do something with that.

I'd like to replicate this effect and did some research, about progressive images and such. Also, this website: 'css-tricks.com the-blur-up-technique-for-loading-background-images/' explains about loading a small image first and blur it to keep loading times low until the actual image has been downloaded.

But I can't seem to find how they did this trick at <http://www.e-flux.com>.

All info is appreciated!