Draw an array of rectangular boxes

Hi,

I need to draw an array of rectangular/square boxes over an array of white spots in the attached figure: img_1 using Matlab code as shown in figure: img_2. I also need to have a control over the dimension of boxes. Like if I have more number of boxes, say 8x8, then I should be able to automatically change my box dimension to 8x8 with all the white spots lying within (centre) of the boxes.

I will be very grateful, if anyone helps me in this regard.

Thanking You!