Join Jan Kabili for an in-depth discussion in this video Converting a background layer for masking, part of Photoshop CS4: Layer Masks in Depth.
You can add a layer mask to lots of different kinds of layers, everything from a regular image layer, to a type layer, to a Smart Object layer and more, but there is one kind of layer that won't take a layer mask and that's a background layer. And unfortunately, you are going to run into background layers a lot, particularly when you are brining in an image from a digital camera. It often comes in with a single layer that's a special background layer. In this movie I'll show you how you can convert a background layer to a regular layer, so that you can add a layer mask.
Take a look at the Layers panel. Here you see this image has a single layer and it is a special background layer. The name of the layer is background, and that name is in Italics, and notice that there is a lock on this layer. Those are all signs that this is a special background layer that won't take a layer mask, and you can tell that it won't because if you look at the layer mask icon here at the bottom of the Layers panel it's grayed out, and when I move my mouse over it, I get this cancel sign and if I go up to the Layer menu at the top of the screen and try to add a layer mask that way, that command is grayed out as well.
So what I need to do whenever I have a background layer on which I want to put a layer mask is to convert that layer to a regular layer. There are two ways to change this layer to a regular layer. The traditional way is a little bit hard to remember. It's one of the secret handshakes you just have to know in Photoshop, and that is to go up to the Layer menu and choose New, and then choose Layer From Background. That opens the New Layer dialog box and what you are trying to do here is just change the name of the layer to a regular layer name.
You can leave it at the default Layer 0, and click OK, and this is now a regular layer with a regular layer name, there is no lock on the layer, and if you notice, the layer mask icon is now available. Clicking that icon will add a layer mask. But there is even a better way to deal with adding a layer mask to a background layer in Photoshop CS4 and that's to use the Masks panel. So I'm going to undo the layer mask I have just added, by pressing Command+Z on the Mac, Ctrl+Z on the PC, and I'm going to step back one more step by holding the Option key and pressing the Command+ Z on the Mac, or holding the Alt key and pressing Ctrl+Z on the PC.
Now I have got a background layer again and as before, I don't have the option to add a layer mask using the Add Layer Mask icon at the bottom of the Layers panel. However, the new Masks panel still allows me to add a layer mask by clicking the Add Pixel Mask icon right here, and notice what happens when I do that. Photoshop not only adds a layer mask. It also converts that background layer into a regular layer all in one step. So this is the most efficient way to do it and just keep in mind that the next time you are trying to add a layer mask and you cant do so, odds are it's because that layer is a special background layer.
And now that you know how to deal with it, it should be no problem to add a layer mask to that layer.
- Adding grayscale pixels to layer masks to hide and show layer content
- Refining the edges of layer masks in the Refine Mask dialog box
- Using filters and adjustments to manipulate layer masks
- Blending photographs into composites by applying gradients to layer masks
- Using layer masks with Smart Objects and Adobe Camera Raw to combine different adjustments of the same photo
- Simulating shallow depth of field and targeting sharpening with Smart Filter masks