ok i try and it's ok : You have to put in PD : send /md8key/ctrl_layer_alpha/1 0.2 for example. And it's change your alpha channel in Layer 1 : i put a simple documentation soon. i can send you the pd patche if you want : #N canvas 285 312 821 543 10; #X obj 56 344 sendOSC; #X floatatom 56 371 5 0 0...