It's a simple question
Can you search for images by sketching a similar image?
I went looking online for a search engine that had implemented this feature, which I'll call image-search-by-sketching.
Update: Since I wrote this piece, GaZoPa no longer exists. In the meantime Google has implemented image-search-by-image. You can't sketch, but you can use an existing image.
Googles implemetation of image-search-by-image is did both a good and bad job when I tried it last (December 2011). When I tried with my test image (dog-shape below), I got this blog post, which is good. But the related images are way off, number one related image is a picture of a shoe?
I can see the similarity to my dog-shape in the results that Google suggested, but I didn't get a dog. No doubt it is a hard problem, and what I wish for is highly semantic, in the sense that I want the search engine to recognize that I'm looking for a dog. In my test below, GaZoPa could have gotten it right for a number of reasons. Maybe they simply had many fewer items in their database to match the dog against, and the best match happened to be... a dog? I guess I'll never know. R.I.P. GaZoPa.
And so I went looking for such a search engine...
First thing I did, was ask this question on Stackoverflow and got an reply which pointed my to a couple of cool websites.
These are all cool websites, but at first not exactly what I was looking for. After trying GazoPa I realized that the website is almost exactly what I was looking for (a service that allows you to sketch-up an image query).
GazoPa allows you (among other things) to upload an image, and performs a search for similar images. I'm not quite sure which images are in its index, but I proceeded with the following experiment. I drew up a rather crude dog in Dia, and uploaded this image to GazoPa. Here is the dog:
It actually gave some pretty decent results, with this one being the first hit:
It is not hard to imagine a site that combines the sketching I did in Dia with the GazoPa service.
Update: Unfortunately GazoPa no longer exists. I guess you combine Google image search with a drawing program, but it would be more fun to do it with an indie search engine.