Has facebook changed its image rendering logic recently?

Since the past few months, I've been noticing that they tend to some kind of pixelated image first which then gets replaced by a much better image.

Is this some开发者_如何学Python kind of trick to reduce perceived latency by facebook?

Or is it Chrome doing it?

i think it's progressive image rendering. Quote from the linked blog

Images already render progressively in a web browser -- but you can do even better. Simply save your GIF or PNG images with the "interlaced" option, or your JPEG images with the "progressive" option.

This blog might answer your query - checkout following links -

Image Optimization Part 3: Four Steps to File Size Reduction

Image Optimization Part 4: Progressive JPEG…Hot or Not?