I am developing an android application for analyzing chess games based on series of photos. To process images, I am using OpenCV. My question is how can I detect that there is a player's hand on a picture? Because I would like to filter those photos and analyze only the ones with the only chessboard on them.

So far I managed to get the Canny, so from an image like that
original image

![](https://i.stack.imgur.com/qgxJA.jpg) 

I am able to get that canny

![](https://i.stack.imgur.com/rR3Iv.jpg).

But I have no idea what can I do next...

The code I used to get Canny:

```
Mat gray, blur, cannyed;
cvtColor(img, gray, CV_BGR2GRAY);
GaussianBlur(gray, blur, Size(7, 7), 0, 0);
Canny(blur, cannyed, 50, 100, 3);

```

I would highly appreciate any ideas and advice on what to do next and what OpenCV functions can I use.