How Google Photos finds trees?
When a friend posted on facebook that if he types alligator in his Google Photos search page, it can find all the photos of the alligators in his images, even the ones which are not tagged. I was intrigued …
If you want to learn how it does work go to last section of this blog. I have detailed the links, both for general reading and technical one. Let me just dazzle you with some results here.
So I searched for trees in my photos,
It was even able to find few looking like trees, for example following from Museum of Fine Arts exhibition
Which to me made sense, one can look at the texture, shape and colors. Thus inferring that some image has a tree in it. They might have added some context too, if there is a horizon etc.. (I already knew that they are using CNN, this was me trying to make sense of if I did not knew that they were using CNN).
What really surprised me were results below. One on the left has no color, none of the tree like texture and very thin tree like structure. On right there is an image in which tree has been made blue (it’s art installment where trees were colored blue to represent veins carrying oxygen), so it cannot use the color cues.
Gainesville Blue Trees art installment
That made me think might be they using little more than just image cues, they might be using similarity among images and see if there is any other similar image, that has been labeled, has been tagged by someone or has some caption or description. Which in this dan and age is fair and smart thing to do.
I remembered a very old paper, I think it was from UCF Computer Vision Lab (I think one of the students of Mubarak Shah), where they were trying to distinguish between the grass, shrubs, trees, … and it was not an easy task. So I experimented with it. Next thing I searched was “grass” and yes results were quite different. Although it was not as accurate, however it did made sense.
Terms like “food” give the most worse result. However, more defined objects give much better result, for example it was able to find “cycle” that was not even the main part of the image, similarly results for car and airplane were good. For searches on terms “Chair” it did an interesting thing. It found people in sitting pose, most of these were people who were sitting on Sofa or on the ground, but it made an association of human pose with the concept of “chair”.
How Magic works? (aka how google can do these amazing things?)
If you want to have a Google’s view of how the ‘magic’ works have a look at this blog http://googleresearch.blogspot.com/2013/06/improving-photo-search-step-across.html. If you are looking to learn something out of it, have a look at Freebase, CNN, Dr. Hinton…. and that their final layer is just linear classifier. If you are interested in getting some technical know-how, have a look at Dr. Hinton’s paper “ImageNet Classification with Deep Convolutional Neural Networks“.
However, we know things have moved at a quite fast pace, about a year ago there was an announcement by google that they can now provide “natural description of images” http://googleresearch.blogspot.com/2014/11/a-picture-is-worth-thousand-coherent.html. Technical stuff to look for RNN (recursive neural network), how they are using for machine translation, have a look their paper, etc….
