Wednesday, August 19, 2015

Tutorial / Photoshop: layers and layer masks

Remember the last post, where we talked about changing colours in photoshop? Well, in that post we promissed we'd get back to you on layers and layer masks in Photoshop. It might sound difficult, it might look tricky but it actually isn't. Stick with us through this post and I bet you'll agree with us afterwards. 

So according to Adobe you should see a layer like a pancake. Only the top pancake is visible. Or actually, as Adobe puts it: Photoshop layers are like sheets of stacked acetate. You can see through transparent areas of a layer (a hole in the pancake) to the layers below.

When you open an image in Photoshop, it opens as a (background) layer. This is where the editing starts. Most of the time, you'll duplicate the first layer (CTRL J) and start editing on that particular layer. If in the unlikely case it goes terribly wrong, you just throw away the diplicate of the first layer. You'll still have the unedited picture you started out with. 

Keep in mind that we're talking a stack of pancakes here: all layers are put on top of the other in Photoshop. The first thing you see - how logical - is called the top layer. 

Let me show you an example: 
In this image, you see the picture with layers. The top layer is black and white and the layer underneath is in color. 
You can turn off the top layer by clicking on the little eye in front of the Layer 1 (right hand side of the screen). Voila! Now you get the coloured version of the picture.

With a basic understanding of layers, the next move is to talk about layer masks. With a mask you have the control over the transparency of that particular layer. 

When working with layer masks, keep in mind this utterly important rule: White Reveals, Black Conceals. So if you have two layers and you add a white mask to the top layer, it shows everything on that layer. 

Here's some visuals: starting out with a picture with 2 layers, a blue top layer and a red second layer. 
Adding a white mask to the (blue) top layer: use the Add Vector Mask icon. You can use the same icon in the layers panel by using the Alt (windows) or OPT (MAC) key. 
And now adding a black mask (white reveals, black conceals!) to the top layer: 
the blue is gone! Hidden by the black mask. 

So when you have this stack of pancakes. And you'd like to show not only the top pancake but also a bit of the underlying pancake, you should use the brush and paint in the opposite colour. When using a white mask, you can make the underlying layers visible by painting with a black brush and vice versa. 
And vice versa. 
Do take a look at the right hand side with all the layer and layer mask info: in both cases the mask changed. The black mask changed to white where you have painted (remember: white reveals, black conceals) 

So there you have it. A basic tutorial on layers and layer masks. In the beginning you might find working with layers confusing. You might mix up white and black layers. Another nifty trick to remember is CTRL I (i as invert) you can easily switch between white and black layers.

I find layer masks extremely helpful. For example to blend pictures together. Think of a sunset where you want a darker sky and nice silky water. In that case you take 3 pictures: 
- one for the sky (underexposed), 
- one for the silky water (over exposured) and 
- one right exposed image

Now you can blend them together in Photoshop using layers and layer masks. That gives you a great control over your creativity and result. I have always found the videos from Serge Ramelli really helpful, easy to understand and very instructive. He starts with some editing in Lightroom and then blends his pictures together in Photoshop.

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