Question

I was wondering how google is capturing all those websites that are featured in google’s instant preview? I’m sure they are not using a thumbnail service (like http://www.thumbalizr.com, websnapr.com, snapcasa.com, thumbshots.com) but rather use their own software. BUT: given that google captures A LOT of websites, they must have a very sophisticated system. PLUS: this generates HUGE amounts of data (jpgs?).
Does somebody have more insight into how google does this?

Answer 1

It’s hard to say, but here’s some info from a Google project manager discussing it:

http://googleblog.blogspot.com/2010/11/beyond-instant-results-instant-previews.html

It says in part:

“we match your query with an index of the entire web, identify the
relevant parts of each webpage, stitch them together and serve the
resulting preview completely customized to your search—usually in
under one-tenth of a second”

That plus looking at the source of a preview page suggests that they’re using their own index (the same webcache.googleusercontent.com that is used to serve the Cached pages) to serve JPEG Base64 image strings as screenshots.