The solution Picture is 100x100 Pixels. The white dots may indicate symbolize a certain sequence of numbers or a code, in form of numbers. For instance, if the 70th pixel is the first white pixel to appear, the first number will be 70.
Update: it might actually be using steganography.
Using the different pixels some sort of a file might pop-up.
I didn't have any luck with the few free online steganalysis tools I threw at it, but I'm an utter neophyte in that area.
