Photoshop_User_-_February_2016

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content that already has lower Opacity, but Fill can’t add back

Opacity to content.

Blend If: The third kind of layer alpha, found in the Advanced

Blending section of the Layer Style dialog, is called Blend If. This

alpha is only applied to specific kinds of content based on the

brightness value (either gray or individual color channels). Like

Fill, it only considers actual content; layer styles are ignored.

Blend If also has a trick up its sleeve. It uses a comparison

function (the “if” part). Blend If can use the current layer infor-

mation (content and instructions combined), or it can use the

output from a lower layer. In plain language, it says to “blend

this layer’s content with whatever is below if some criteria are

met.” The criteria are the brightness values of either layer.

When using Blend If for This Layer, layer styles aren’t

affected—it behaves like a selective Fill Opacity. But when

using Underlying Layer, layer styles are affected.

Mask: There are two more features to talk about that con-

cern layers and transparency: clipping and masks. Remember

above when I said alpha instructions are actually channels?

Well, here’s where that information starts to make sense.

A mask is really an alpha channel attached to a specific layer

(or group of layers). An alpha channel is a grayscale image

that’s applied to another image and provides instructions

about what’s transparent and what’s not. In the case of

masks, Photo shop treats white as opaque, and black as trans-

parent. This is mostly independent of other alpha instructions,

and gets added on top of everything else. That means you

still have access to Content Opacity, Layer Opacity, Fill, and

Blend If, and then the layer mask gets added after all of that.

Clipping: Clipping refers to using the content of one layer

as a mask for another. A clipped layer has content and is

above a target layer with content. The clipped layer’s content

only shows up where the target layer content exists. Let’s go

back to our first example and switch the order of the text

and image layers. The text is now obscured. But if we clip

(Option-Command-G [PC: Alt-Ctrl-G]) the image layer to the

text (target) layer, the image content now fills the text.

Next issue, we’ll tackle blending modes and adjustment layers

in terms of how they behave in a stack. It’s gonna get geeky

in here! ■