Yesterday I made an interesting mistake..
I'd seen an animated GIF of a cat. I thought I'd like to see it in detail, so I did what I thought was an obvious search. I did:
[ cat filetype:gif]
on the regular search page. I was VERY surprised when I saw ZERO results! That's funny...
You know and I know there are about a billion images of cats on the internet, so what's going on?
I asked a bunch of friends, all of whom said "that's odd!" Until finally a wise person pointed out that...
... you can't use FILETYPE: on a regular search...
... you have to use Images.Google.com...
Yeah, Really. Even though the search UI says "All"
Turns out that it's not really "All."
In particular, to find an image, you have to use Images.Google.com. Likewise, if you want to find a scholarly article, you have to use Google Scholar, you can't get it from plain old All search.
So, if you want to see the Google Scholar version of my 1993 paper on sensemaking, you won't find it by searching on regular Google.
I mean, you'll FIND it at a repository such as ACM.org or ResearchGate.net, but regular Google search won't take you to Google Scholar--you have to go there first manually (Scholar.Google.com), and then search there to get to the Google Scholar version of the paper.
Just as with my filetype:gif search, Google's "All" search really means regular web pages, plus a few other kinds of documents--PDF, PPTs, PPTX, XSL, XSLS, KML, KMZ, etc. (Notice that filetype: works for all of those.)
It just doesn't work for JPG, GIF, ICO, TIFF, or other image file types.
Note that if you do a slightly different search, putting GIF in the query, Google will figure out your image-search intent, and give a bunch of images on the SERP. That's a pretty good workaround.
But clicking on any of those images jumps you over to Images.Google.com, where you'll see just what you'd expect, regular old Image search for [cat gif]
Suppose you NOW want to search for a different type of image file--say you'd like JPG files. It's HERE that you can add in the filetype:jpg filter, like this:
You could change that JPG to ICO (icons), or PNG, or GIF, or SVG. They're all different file formats for images. It's here, in Images.Google.com that the filetype operator for image file types will work, not in "regular" Google search.
For example, here's the [ cat filetype:ICO ] search in Images:
You can search for GIFs on Bing search, but you have to use the Tools option (see below). I don't know of any way to specify the file format type in the query. (For instance, how would you find a non-animated GIF image on Bing? Don't know.)
As someone once said (maybe Issac Asimov?),
"The most exciting phrase to hear in science, the one that heralds new discoveries, is not “Eureka!”but “That’s funny …”
In this case, my that's funny moment was getting zero results for a query that I thought would give me millions. A bit of investigation taught me this important lesson:
FILETYPE: for images only works in Images.Google.com
That's a useful thing to know. Remember, "All" doesn't always mean "ALL."