Okay but how do you compute an image? How would your browser -- or any other client software -- know what's the hero image of a blog that you never visited before, for example?
I feel like I am missing something important in your comment.
The article describes computational method of rendering frosted glass effect. You can achieve the same thing by rendering the effect once (then upload to a sever) and have client download the rendered image. Or you can compute the frosted glass effect. What's better? That's the argument.
Ah, sorry, I didn't make it as far in the article.
IMO it really depends on the numbers. I'd be OK if my client downloads 50KB extra data for the already-rendered image but I'll also agree that from 100KB and above it is kind of wasteful and should be computed.
With the modern computing devices we all have -- including 3rd world countries, where a cheap Android phone can still do a lot -- I'd say we should default to computation.
I feel like I am missing something important in your comment.