Find the following masks in the corresponding locations:
Clank Mask To obtain the Clank Mask, after several of the spring pads in Tanker 1, you have to climb up a wall. When you get to the top, turn around. There is another wall you can climb. Hover over to it, climb it, then turn around again. Hover over the picture on the ledge across from you, then smash it to find the Clank Mask.
Human Daxter Mask After the first pipe slide in the Hotel level, you must run up a slope. When you get to the top, turn around and you should see a ledge. After you get the Flamethrower attachment, you can reach it. On the ledge is the picture. Smash it to find the Human Daxter Mask and Hat.
Jak Mask Go to the second cell block that is patrolled by three guards in the Prison level. Sneak behind the guards and follow them moving counter-clockwise. Collect the key that is hidden behind the second pillar. Use it to open the first door you see to the northeast. Smash the picture on the shelf to find the Jak Mask.
Ratchet Mask After the part where you jump from train to train in the Subway level, you will come to a section where you have to climb up some net, while avoiding the energy going up it. Once you reach the top, look down the side closest to the entrance to the next part of the level. Drop down onto the ledge, then smash the picture to find the Ratchet Mask.
Samos Mask After the first bug zapper in the Lumbermill level, you have to pass a few saw blades. Then, look to your right to see a tunnel with a saw blade in it. Look to your left to see a stream. Jump off the platform to your left and hover, while staying close to the wall. After a few seconds, you will come to a small space in the wall. Inside is the picture. Smash it to find the Samos Mask. Sly Cooper Mask There is a box behind the warp gate to Emerald Isle in the City Port area that you can jump onto. Jump up on it, then go behind it and turn back the way you came. You will see the back of the box has a picture on it. Smash the picture, then go inside the box to find the Sly Cooper Mask.