Google drag and drop image search

[shaunm]

Hi,

How come Google shows the exact places of an image when we drag and drop in its image search? How does it read an image even after changing the visible name of the image and changing its size from the original?

If it can understand a image, why does it ask to use image alt tags in images saying that the spiders cannot understand what an image is about?

What do I miss here? Could anybody help me?


Thanks,

[Andy Langton]

Google is visually matching the picture with others in its database. That is fine when you publish an image that is directly reproduced elsewhere (because then Google has sufficient text to guess at the image contents). But it doesn't work very well with unique images.

[lucy24]

Would it surprise you to hear that alt tags are not actually for search engines? They are primarily for humans who, for one reason or another, can't see the image. It does not help much to make an alt that says "picture that looks very much like the one at www.example.com/directory/images/filename.jpg".

Especially if the picture doeesn't look very much like {et cetera}.

When the drag-and-drop image search was first introduced I found some pretty hilarious results by asking for images matching a photograph of one of my rats dozing in a bakery bag. About half the results showed something with eyes in close-up, matching the middle of my picture. The other half were random scenes with strong dark/light contrast, matching the visual weight of my picture.