How to divide a binary image into equal sized squares?

I have a binary image,specially a hand gesture. whatever the orientation will be we have to bring back to them into vertical orientation.Now my next work is to consider only upper portion of the centroid only.The thing is that I have to scan from centroid column to right upto width to find out the first column which will consists off all black pixels,then from centroid column to left and finally from centroid row to top for the similar thing. now the distance from centroid to the right,left and top will be calculated. the max distance or length will be considered and have to take two square of sides equal to the length have to take from both sides means left side of centroid column and right side of centroid column. Again I need to divide these square to four equal quadrants. But these quadrants can be rectangular and you can divide by following any image spitting rules. After diving these two square will get 8 parts in total. now for these 8 parts I have to find out f=no. of white pixels/area of the part. These thing I have to repeat for a dataset of 1000.