Working With Layer Masks

What is a layer mask?

Layer masks are a basic and important tool in Photoshop to create image manipulations. Among other uses, they allow you to ‘stack’ multiple images and expose only certain parts of the image/s above the base layer, creating a composite image.  You can do this using an eraser – but that is DESTRUCTIVE.. if you remove something you wanted to keep, you have to go back to before you erased that spot.. possibly undoing other work.  Layer masks allow you to work NON DESTRUCTIVELY – if you remove something you wanted to keep its super easy to get it back, and you dont lose your work.

Lets Get Started

We’re using images from our recent Splash! workshops and the first set is by Beck Faldon

Beck Faldon

The goal is to combine all three, so we have the iceblock and both splashes in the one image.  Hence the magic of layer masks.

  1. Open Photoshop and go to File>Scripts> Load files into stack.  From the little window that pops up, click ‘browse’, then find and select the images you want to use.  As the images I’m working with were taken on a tripod with virtually no difference between them, composition wise, I am also going to place a tick in the box ‘attempt to automatically align source images.  Then click ok. 
  2. Photoshop will now open all files, and if you click on your layers tab you will see they are all there, one on top of each other. You will also see that each layer has an eyeball beside it.. when the eyeball is visible that layer is visible, if you click the eyeball it turns that layer off.  Its still there, but no longer visible.

    Layer Stack

  3. Click the eyeball on the top layer and turn it off for now.  We are going to work on the second layer first up. To Add the layer mask, click on the second layer (the middle one) so its active, then look to the bottom of the layers tab.  Click on the white rectangle with a black circle in the middle… it looks like the japanese flag.  You will now have a white rectangle beside your second layer.  It’s important to remember that when you are painting .. you must be doing it on the mask not the image.  See below, the white bounding box around the white mask… that shows me I am painting on that.  If you are painting and it starts turning black or white, you are painting directly on the image.  Go back a few steps until you have undone that, click on the white mask to make the mask active and start again. 

    First Mask

  4. The key to layers masks is remember that white reveals, black conceals.  The layer mask is white… so you need to paint with black. Choose your brush tool, select 0% hardness,m then at the bottom of your main toolbar on the left click the black palette.  Clicking the little double sided arrow above your black and white palettes will toggle between black and white. Where you see 100% opacity on the image above, bring it down to about 70% and you will see the layer below – it will help you choose what to reveal. When you are finished bring the opacity back up to 100% As you paint, the mask will start to show black areas, where you painted… concealing the top layer, and revealing the layer below. To get into tight spots make your brush smaller and change it to a 100% hard brush. If you take off parts of the image you want to keep, go back to your palette and click on the white palette to swap to a white brush, now paint back the area you lost.  As all the images were taken on a tripod and there is no differences except the cup.. all I am doing is painting the splash above the cut to combine the splash from both images into one.


  5. You can now see that there is black on your layer mask. There is where I brushed over the cup, the black area of the second layer is now hidden where its black, revealing the splash below. Now we want to bring the ice cube into the pic. Turn the top layer back on, by clicking the empty box on the layer (where the eyeball isnt) and the eyeball will come back, as the layer is now turned on. Dont panic when you see that you’ve lost the splash, its all still there, just hidden below. Click the top layer to activate it then click the ‘add layer mask’ icon again (the japanese flag). You will have another white rectangle now just like the second layer

    Top Layer

  6. The area we want to expose now is the entire cup, keeping the falling icecube above.  Select the black brush again and paint over cup to exposed the splash but keep the ice cube.  Again if you make a mistake, just change to a white brush and paint it back.
  7. Once you have finished simply go to Layer>Flatten Image and edit in your normal way.  In the case of this one, I cropped and cloned out the inside of the bag you could see in the sack. (it was there to puff the sack up and make it look fuller).  I also added a subtle vignette

    Finished Composite

Some More Examples

Liz’s Images

Finished Composite

Deb’s Images

Finished Composite

Masking has many uses, if you are into family portraits and you shot them on a tripod, you can layer the images and remove heads.. cause its a battle to get everyone looking at the camera, eyes open, smiling … layer the images and you can brush in our out the ‘offending’ head. Hope you found this helpful.. feel free to leave a like or comment 🙂