If you simply make a selection, then drag it with one of the selection tools, you move the selection boundary but not its contents. If you want the pixels to move as well, you have to use the Move tool. Fortunately, no matter what tool is selected, you can always temporarily get the Move tool by holding down the Command key. Note that you can hold down the Option key while you drag to copy the pixels as you move them (moving a duplicate of the pixels).
When you move or copy selected pixels with the Move tool, you get a floating selection (sort of like a temporary layer that disappears when you deselect). While the selection is still floating, you can use the Fade command (in the Edit menu) to change its opacity or blend mode.
With the Move tool, you can move an entire layer around without selecting anything. When you do have something selected, you don't have to worry about positioning the cursor before you drag. This is a great speedup, especially when you're working with heavily feathered selections.
Tip: Arrow Keys Move, Too
When moving pixels around, don't forget the arrow keys. With the Move tool selected, each press of an arrow key moves the contents of your selection by one pixel. If you add the Shift key, the selection moves 10 pixels. Modifier keys work, too: hold down the Option key when you first press an arrow key, and the selection is duplicated, floated, and moved one pixel (don't keep holding down the Option key after that, unless you want a lot of duplicates).
Remember that you can always get the Move tool temporarily by adding the Command key to any of these shortcuts. Pressing the arrow keys with any tool other than the Move tool moves the selection without moving the pixels it contains. This is an essential technique for precision placement of a selection.
If you've got the Move tool selected (press V), and nothing is selected when you press the arrow keys, the entire layer moves by one pixel. Add the Shift key to move 10 pixels instead.
Tip: Moving Multiple Layers
One of the problems with layers is that you often can't do the same thing to more than one layer at the same time. An obvious exception in Photoshop CS2 is moving layers.
If you wanted to move more than one layer at a time in previous versions of Photoshop, you had to link them. ln Photoshop CS2, you can simply select all the layers you want to move: Shift-click in the Layers palette to select contiguous layers, Command-click to select noncontiguous ones.
Tip: Duplicating Layers
Duplicating a layer is a part of our everyday workflow, so it's a good thing that there are various ways to do it.
The method you use at any given time should be determined by where your hands are. (Keyboard? Mouse? Coffee mug?)
Tip: Duplicating and Merging Layers
You can merge a copy of all the currently visible layers in a document into a new layer (without deleting the other layers) by holding down the Option key when selecting Merge Visible from the Layer menu (or, better yet, just press Command-Shift-Option-E). In previous versions of Photoshop, Option-Merge Visible copied all the visible pixels into the currently selected layerin CS2, it always creates a new layer unless the currently selected layer is empty.
Tip: Copying Pixels
Layers are a fact of life, and with Photoshop it's not uncommon to find yourself with more layers than you know what to do with. If you make a selection and select Copy, you only get the pixels on the currently active layer(s) (the one(s) selected on the Layers palette). If you want to copy all the visible layers, select Copy Merged instead (or press Command-Shift-C).
Some people use this technique to make a merged copy of the entire image (not just a selection). It works, but the previous tip provides a faster and less memory-intensive way of doing the same thing.
Tip: Pasting Pixels
Pasting pixels into a document automatically creates a new layer (unless your image is in Indexed Color mode). So what about the Paste Into (Command-Shift-V) and Paste Behind (Command-Shift-Option-V) features (which are available when you've made a selection)? When invoked, each of these adds a new layer, but it also adds a layer mask to that layer in the form of the selection. This is one of the fastest ways to build a layer and a layer mask in one step: Draw a selection the shape of the layer mask you want, then perform a Paste Into or a Paste Behind (depending on the effect you're trying to achieve).
Tip: Drag-and-Drop Selections and Layers
Most Photoshop users can't envision a world without Cut and Paste. However, there are times to use the Clipboard and times not to. In Photoshop, you often want to avoid the Clipboard because you're dealing with large amounts of data. Every time you move something to or from the clipboard, you eat up more RAM or hard drive space, which can slow you down.
If you want to move a selection of pixels (or a layer) from one document to another, you can do so by dragging it from one window into the other (if you've got a selection, remember to use the Move tool, or else you'll just move the selection boundary itself). Photoshop moves the pixels "behind the scenes," so as to avoid unneeded memory requirements. If you're trying to copy an entire layer, you can also just click on its tile in the Layers palette and drag it to the other document's window.
Tip: Placing your Drag-and-Drop Selection
In the last tips we talked about how you can drag and drop a selection or layer from one image into another. When you let go of the mouse button, the selection is placed into the image right where you dropped it. However, if you hold down the Shift key, Photoshop centers the layer or selection in the new image. If the two images have the same pixel dimensions, the Shift key "pin-registers" itthe layer or selection falls in exactly the same place it was in the original document.
Tip: Copying Layer Masks
In previous versions of Photoshop, copying layer masks from one layer to another was a fairly painful process. In Photoshop CS2, you can simply click the layer mask's tile in the Layers palette, and Option-drag it to the target layer.
Guides, Grids, and Alignment
Moving pixels is all very well and good, but where are you going to move them to? If you need to place pixels with precision, you should use the ruler, guides, grids, and alignment features. The ruler is the simplest: you can hide or show it by pressing Command-R. Wherever you move your cursor, faint tick marks appear in the rulers, showing you exactly where you are (you can also follow the coordinates on the Info palette).
You can add a guide to a page by dragging it out from either the horizontal or vertical ruler. Or, if you care about specific placement, you can either carefully watch the measurements on the Info palette as you drag, or select New Guide from the View menu. (If you don't think in inches, you can change the default measurement system; see "Tip: Switch Units," later in this chapter.)
You can always move a guide with the Move tool (don't forget you can always get the Move tool temporarily by holding down the Command key). Table 2-1 lists a number of grids and guides keystrokes that can help you use these features effortlessly.
Tip: Snap to Ruler Marks
We almost always hold down the Shift key when dragging a guide out from a ruler; that way, the guide automatically snaps to the ruler tick marks. If you find that your guides are slightly sticky as you drag them out without the Shift key held down, check to see what layer you're on. When Snap To Guides is turned on, objects snap to the guides and guides snap to the edges and centers of objects on layers.
Tip: Switching Guide Direction
Dragged out a horizontal guide when you meant to get a vertical one? No problem: Just Option-click on the guide to switch its orientation (or hold down the Option key while dragging out the guide).
Tip: Mirroring Guides
If you rotate your image by 90 degrees, or flip it horizontally or vertically, your guides will rotate or flip with it. You can stop this errant behavior by locking down the guides first (press Command-Option-semicolon).
Tip: Guides on the Pasteboard
Just because your pixels stop at the edge of the image doesn't mean your guides have to. You can place guides out on the gray area outside the image canvas and they're still functional. This is just the ticket if you've got a photo that you need to place so that it bleeds off the edge of your image by 0.25 inch.
Tip: Changing Guides and Grids
Guides are, by default, cyan. Grid lines are, by default, set one inch apart. If you don't like these settings, change them in the Guides, Grid & Slices pane of the Preferences dialog box (you can select this from the Preferences submenu), or just double-click on any guide with the Move tool (or Command-double-click with any other tool).
Alignment and distribution
People often use the alignment features in page-layout applications, but Photoshop has alignment and distribution features, too, and they're a godsend for anyone who really cares about precision in their images (we find them particularly useful when building images for the Web). Here's how you can align objects on two layers.
Tip: Locking Alignment
Normally, when you align along the left edges, Photoshop moves all the layers except for the one that has the leftmost data. (Or the rightmost data when aligning left, and so on.) You can force Photoshop to lock one layer and move the others by linking the layers instead of selecting them: Select them all, click the Link icon in the Layers palette, then click on the layer you want to remain in place. Now when you choose from the Align submenu, all the layers move except for the currently selected one.
If you select three or more layers, you can also distribute the layers instead of aligning them. For example, if you have four small pictures that you want evenly spread across your Photoshop image, you can put each one on a separate layer, link them all together, and choose Horizontal Centers from the Distribute submenu (it, too, is under the Layer menu; see Figure 2-6).
Figure 2-6. Distributing layers
When distributing layers vertically, Photoshop "locks" the layers that are closest to the top and the bottom of the image canvas; when distributing horizontally, it locks the leftmost and rightmost layers. All the layers in between get moved. For example, if you choose Vertical Centers from the Distribute Linked submenu, Photoshop moves the layers so that there is an equal amount of space from the vertical center point of one layer to the next.
Tip: Aligning to the Canvas
Aligning two layers together is all well and good, but we often find we want to align something to the image canvas itself. For instance, you might want to center some text horizontally in the picture. Here's how you can do it.