EXIF Metadata may contain plenty of useful information about images like when that photograph was taken, which lens was used, what was the camera make as so on.
The million dollar question is whether Google uses Exif data for image search rankings?
Peter Linsley, product manager for Google Images, earlier said:
I’m a huge EXIF fan, it makes perfect sense for the image itself to be able to carry pertinent metadata and we’re always looking at ways it could be used especially as adoption rises over the coming years.
Later Matt Cutts also mentioned EXIF in one his Webmaster videos on how image only websites can improve their search rankings in Google.
While none of them confirmed, it looks like Google may be reading Exif information from your images.