https://editor.p5js.org/Pilou/sketches/5A7DeQN-H
Bravo ! With your blocks the program works perfectly
Just drop an image PNG (<=1024*512) with a transparent background for have an interesting result! 
Here if you have not for test: image 1
image 2
I have only 2 messages on the console who are out of my knowledge!
If you can take a look:)