Understanding Masks with Layers

Masks are one of the most useful tools in PSP, but they can be difficult to understand, and harder to intuit. Here we are going to explore using masks with layers (I'm assumming you understand layers!). This is not a tutorial, but a set of exercises that helped me get a feel of how masks and layers work together in such a useful way.

OK, first things first, what is a mask?. The nearest thing I've come to a sort of "feely" description is to imagine spray painting through a lace curtain. The lace curtain "masks" the spray paint so the spray only paints where the holes are.

You can also think of masks as stencils, cut-out shapes that you can view through.

Basically, PSP use masks as greyscales, so you can have varying degrees of "maskness". Don't worry if that doesn't make sense, we'll come back to it later. Basically, a black area masks your image perfectly, a white area provides no mask at all.

Basic Setup:





• Take two images, of the same size (crop them if necessary)

• Make sure the images are quite different from each other

• Make sure neither image has much red in it! (you'll see why later)

• Set them up in one image so they are layered.

• If you are using these images, then the photo is the top layer, the text is the lower layer.

  Create a Mask:

• Firstly, we are going to create a mask in the upper layer

• Make sure the upper layer is selected

• Choose Masks, New, Hide All.

  This creates a mask that hides all of the layer, that is it provides no masking at all. Your top layer should have disappeared entirely. In other words the layer has been completely masked off or hidden.

• OK, next we are going to make the mask itself visible, and edit the mask.

• Select Masks, View Masks (Ctrl-Alt-V). You will get a red tint over your entire picture. This is the mask. Red is masked, clear is unmasked.

  If this isn't entirely obvious at this stage, make both layers invisible, you have a red tint over the usual green chequer board. Turn both visibility on for both layers before continuing.

  Edit a Mask:

• Now select Masks, Edit (Ctrl-K). This means you are editing the mask, not the image.

  You may have noticed that your foreground/background colours have switched to greys. Remember, masks are only greyscales.

  If things don't seem right at this stage, select the Masks menu, you should have tick marks next to Edit and View Mask

• Set the foreground colour to white, select a nice fat paintbrush, and just paint over.

• Your upper layer should start to re-appear!

  
  

• Try turning the visibility of the layers off, you will see just the mask, it will be something like this:

  
  

• Remember, the red area (that you paint with black!) is a full mask, the clear area (that you paint with white!) is a clear mask.

• Before we go any further, just experiment. With the visibility of both layers on, paint in white, black, the delete tool and so on, you will see your image, fade, appear and so on.

  Turn layer visibility on and off to see your mask clearly and how it relates to the image that shows through.

Summary so far:

So, what we've seen so far:

1. A mask on the top layer stops it being visible, letting the lower layer show through.

2. We can create a mask quickly by Mask, New, Hide All (Ctrl-Y)

3. We edit a mask using any tool

4. Paint in white to unmask, set the mask clear (but the layer visible)

5. Paint in black to mask, set mask red! (and the layer invisible)

The trouble is, when you write the explanation, it doesn't make much sense because you've got visible masks, invisible layers it all seems counter-intuitive to describe, but it should start to make sense the more you play with it.