Layer masks have got to be one of the most intimidating parts of Photoshop Elements.  They’re one of those tools we hear about from day one, but aren’t exactly sure how to use them or whether the benefit is worth the steep learning curve.

Here’s the good thing about layer masks – once they click, once you get that lightbulb moment, you’re done. There’s nothing complicated about them from that point on.

Today’s the day for your lightbulb to pop.  Ready?

(Oh wait.  Have you conquered masking already?  Here are some articles on advanced topics:

Take a picture like this:

Selective black and white is the classic example for learning layer masks on.  Here’s why:

A layer mask allows you to constrain an effect in Elements to a specific part of your image. If you want part of your image black and white, and part color, a layer mask will let you place the black and white effect only in the area that you want it.

It looks like this in PSE:

This screen shot comes from MCP’s Fusion for Photoshop Elements, by the way.

Every layer in that layers palette from the screen shot above has a layer mask.  It’s the white box just to the left of the layer name.  Notice how the top mask is different – the one on One Click B&W?  That is the layer that creates the B&W effect, and that is the mask that I used to constrain the B&W to the background only.

And how is that One Click B&W different?  It’s got black on it in addition to white.  This brings us to this key point about using layer masks:

Black conceals, white reveals.

In other words, where ever a mask is black, the effect is concealed, or hidden.  Where ever a mask is white, the effect is revealed.  So the black and white conversion is showing only where the mask is white, that is, the background.

Lightbulbs shining yet?

Notice how the black area on the layer mask is pretty much a silhouette of my daughter?  That’s why she is still in color.  I have hidden the B&W from her part of the picture.

So now that you get why you should use layer masks, how do you use them?

  • First off, find the layer whose effects you want to constrain (One Click B&W in this case)
  • Click on that layer to activate it.  See how my One Click layer is darker?
  • If there isn’t a white outline around the mask, click on it.  Once that white outline is there:
  • Select your brush tool and make your paint color either black or white, depending on whether you want to conceal or reveal.

That’s it.  As long as that white outline is around the layer mask, you are painting on it.  However, if that white outline is missing, you’ll actually be painting black and white paint scribbles on your image rather than the mask.  Don’t do that – it will look funny!

I bet some of you can think of other ways to do this same thing in Elements, right?  However, other methods are destructive.

That means that your pixels will be changed forever, once you change them.  But not with layer masks.  For instance, you could add a black and white layer and erase the parts of the B&W that you didn’t want.

Let’s say I did that – I have a black and white layer on top of a color layer.   I used the eraser tool to erase the B&W pixels on top of my daughter, so that the color pixels from the layer below show through.  Ok, fine, the pic looks great, I save it and post it on my blog.  Then I decide that I want to enlarge it and print it to hang up on the wall.  I notice that I painted sloppily and I have color spilling over onto the wood of the rocking chair in several spots.  However, I used my eraser tool on my B&W layer, right?  Those B&W pixels are gone forever and I can’t un-erase them to repair this photo.

But with a layer mask, everything is different. I would pick up my brush tool with white as the foreground color, make sure my layer mask had a white outline on it, and then paint over those areas of overspill on the wood to let the B&W shine through everywhere it should.  As long as I save my file as a PSD to keep the layers, I can make those changes today, tomorrow or 10 years from now.  My pixels will always be there.

Need another reason to use layer masks?

You can vary the AMOUNT of an effect that is applied to various parts of your image. Say that I want to finish by sharpening this image.  However, I don’t want to sharpen evenly across the picture. I’d like my daughter’s face to be the sharpest, her chest sharp, but not as sharp, and I want the rest of the image to retain the nice blur that it has.

So that means that her face needs to be white on the mask (right?) because I want the sharpening effect to shine through.  And the background that I want soft and blurry should be black, because I don’t want any sharpening there.  How about her chest, that I want to be somewhat sharp?  Well, I guess that area should be somewhat white, meaning that a little sharpening is showing.  Or somewhat black, meaning that a little bit a blur is showing.

How about GRAY?

Using the brush opacity slider, which you can see in the tool options bar above, I paint with white as my foreground color at 100% opacity over her face.  That means it’s pure white, and the sharpening is showing through at 100%.  Then, I reduce the opacity of the brush to 50%, which lets 50% of the sharpening shine through.  I paint on her hair and face at 50%, and my resulting layer mask looks like this:

You can see how the mask actually shows where I painted white and where I painted gray, right?  Note that the brush opacity is not the same as the layer opacity at the top right corner of the layers palette.

(That Exact-o-Sharp selective sharpening layer came from MCP’s Fusion also.)

I hope your lightbulbs are all shining brightly now.  Any questions?

If you want more info like this, my March round of Elements classes begins this week.  Check out the topics and schedule here.