5.7. Things You Can Do to Modify a Layer
There are many other ways you can change a layer or the way it affects layers
below it.
5.7.1. Use the Merge Visible command
To create a flattened version of a layer, I usually duplicate the image, flatten it,
copy the flattened image to the Clipboard, and paste that into the original version
so that it becomes its own layer. That's one way to do it, but it's really just an old
habit from days gone by. Here's a much more efficient procedure:
1. Highlight the top layer in the Layers palette.
2. While pressing Opt/Alt, choose Merge Visible from the Layers palette fly-
out menu. When the new layer appears, it is a flattened version of the whole
file.
Just be darned (I'm not allowed to swear) sure that you're holding down Opt/Alt
when you do this. Otherwise, you'll flatten your entire image. C'mon Adobe!
There's already another command that flattens images. The only thing that
requiring the Opt/Alt does is make it possible to mess up. But if you do mess up,
don't panic; just press Cmd/Ctrl-Z immediately to undo the foolish thing you just
did.
5.7.2. Apply Blend Modes
The Layers palette features 23 different Blend Modes (Figure 5-5). They're called
Blend Modes because they cause the layer that's been assigned a Blend Mode to
mix its colors with the immediately underlying layer in a specific way.
Figure 5-5. The Layers palette Blend Mode menu.
These are hard to describe, but Table 5-3 shows how the gradient in the Normal
mode blends with the image in the upper left corner when each other Blend Mode
is applied. Since this gradient contains all of the primary colors, you should get a
good idea of what each mode does. However, there's no substitute for good old
trial and error. Besides, the actual effect can vary considerably by dragging the Fill
and Opacity sliders in the Blend Modes' layer.
Table 5-3. Blend Mode examples

5.7.3. Set the Opacity field/slider
This slider, which is at top left of the Layers palette, always starts at minimum
opacity. As you drag the slider to the left,
the currently chosen layer becomes more
and more transparent. You can also set Opacity to a percentage by entering a
number in the field box.
5.7.4. Set the Fill field
At first glance, this slider seems to do the same thing as its older brother,
Opacitybut it doesn't. If you set Opacity, you're setting the opacity of the blend
mode. If you set Fill, you're setting the opacity of the colors in the fill layer. It's a
very thin line, but there can be a very big difference in how Blend Modes treat a
layer, depending on what the Opacity and Fill settings are.
5.7.5. Use the History Brush tool
The History Brush is very useful for restoring details from the original once you've
imposed a layer effect, filter, or made an Extraction. It paints back either the
original state of the image or a History Snapshot. History Snapshots are stored as
invisible layers at the top of the History palette. You can create a snapshot at any
time by clicking the Snapshot icon at the bottom of the History palette. All the
same brush mod
es and styles that can be applied to the Brush tool can be applied to
the History Brush tool.
5.7.6. Employ the Eraser tool
The Eraser can be extremely useful when you're working with layers and blend
modes. If you want to "paint in" some transparency into the layer, you can preset
the Opacity or Flow (same as Fill for a Layer) of the Eraser Brush. The Eraser can
be used as a Brush, Pencil, or Block. In Brush mode, all of the regular brush
settings are available to you.
5.7.7. Create a Mask
The Mask icon is at the bottom of the Layers palette. If you click it, it will add a

mask to the current layer. If you already made a selection at the time you click the
New Layer icon, it will automatically be masked by the selection. In most cases,
you will want to "blend" the contents of the selection with those portions of the
image that are outside the selection. You do that by choosing Selection Feather
and setting the number of pixels for the width of the feathering stroke. A "feather"
is simply a black to white gradient that follows the path of the selection and is
spread evenly from dark to light. Inside the selection, the mask graduates from
black to 50 percent gray, and outside from 50 percent gray to white. In a mask,
black is 100 percent opaque, while white is 100 percent transparent. You can see
the effect of a feathered mask in Figure 5-6.
Figure 5-6. A mask feathered to 50 pixels.





5.8. Grouping Layers
There may be times when you want to make groups of layers as a part of your
workflow. For example, there may be several masked Curve layers that affect
different parts of the image in different ways. You want to keep all these layers
together so you can move them or turn them off as a group.
Grouped layers differ from linked layers in that the entire group can be made to
have a single characteristic, such as a Blend mode. In other words, the entire group
can be treated as a single layer.
There are two ways to create a group, both are found on the Layers palette fly-out
menu:
 To create a group from existing layers, press Cmd/Ctrl and click on each
layer you want to have in the group. Then choose "Group from Layers" from
the fly-out menu.
 To create an empty group, choose New Group from the fly-out menu. You

can add new layers to that group at any time. Add a new blank layer by
selecting the Group and then clicking the New Layer icon.
You can add an existing layer by simply dragging it to the Group layer where you
want it to reside.
Layer Features That Arrived with CS2
On the rare chance that you're not fully familiar with layers or some of
the new features in Photoshop CS2, here's a quick rundown.

Layer linking
Layer linking allows you to treat multiple layers as a single entity.
So you can move or transform all the layers together into a new
position or drag them into a new Group (see the section,
"Grouping Layers"). You would want to transform linked layers if,
for instance, you had already masked some Adjustment layers to
affect targeted portions of the image so that the targeted areas
remained proportionate. You can link layers temporarily by
pressing Cmd/Ctrl and clicking all the layers you want to link
together. If they're all next to one another, just select the top or
bottom layer in that series, press Shift, and click the layer on the
other end of the series. If you want to unlink layers, select those
you want to unlink and click the Link icon.

Layer mask linking
Speaking of keeping masks in line with the image when you
transform, make sure you link the mask to the image. Layer masks
are linked by default, but you can unlink them by simply clicking
the link icon that is in between the image or adjustment icon and
the mask. Usually, it's the layer mask that's active (selected) by
default because you will likely want to edit the mask by painting
in it or adding a selection to it. If you want to make the image

active, unlink the mask and then click the image. When either the
mask or the image is selected, a black frame surrounds it so you
can immediately see which is active.

Lock transparent pixels
If you have moved a portion of the image to a new layer or
extracted the image from its layer, or have text or a shape on a
layer, the area surrounding that shape will be transparent. By
default, you can tell which parts of the layer are transparent
because you see a checkerboard pattern through the clear parts of
the layer. There will be times when you want to filter or fill a layer
so that only the image pixels are affected. Whenever that's the
case, click the Lock Transparent Pixels icon.

Lock image pixels
Clicking the Lock Image Pixels icon ensures that only transparent
areas will be affected. Be aware that locking image pixels is
destructive because if you fill the transparent area, it changes the
pixels permanently (unless you Undo while that step is still in the
History palette).

Lock layer position
Clicking this icon ensures that this layer will retain its position,
which will keep you from accidentally bumping the layer out of
position when using the Move tool.

Lock all
The Lock All tool doesn't lock all the layersit locks all the locking
options for the currently selected layer. Of course, you could lock
one at a time, but why waste the time?