With Photoshop, Adobe gave us the ability to make more than one layer active at a time. Clicking on individual layers with no keys held will cause individual layers to be active. Command-clicking (Mac) or Ctrl-clicking (Windows) on a layer will add that layer to the other layers that are selected. Shift-clicking will select the range of layers that appears between the layer you Shift-clicked on and the one you clicked on previously. You can also Shift-Command-click (Mac) or Shift-Ctrl-click (Windows) within an image while the Move tool is active to add the layer that appears under your mouse to the layers that are currently selected. There is no limit to the number of layers that can be selected at one time.

Many of Photoshop’s features will be unavailable when multiple layers are selected (such as filters and adjustments) because they were designed to only work on one layer at a time. When multiple layers are selected, you can do the following:

• Reposition by clicking and dragging with the Move tool.
• Change the stacking order by dragging the selected layers up or down in the layers stack.
• Scale or rotate (but not warp) the layers by choosing an option from the Edit>Transform menu.
• Align or distribute the layers using commands found in the Layer menu.
• Duplicate, delete, link or group the layers using commands found on the side menu of the

The Opacity setting at the top of the Layers palette controls the opacity of the active layer. When this setting is lowered, the entire layer becomes partially transparent (transparent is the exact opposite of opaque). If you want to lower the opacity in a specific area instead of the entire layer, you can lower the opacity of the Eraser tool and then brush across the area of the layer you want to become more transparent—that is, unless the background is active. If you use the Eraser tool on the background, it will simply paint with your background color instead of truly deleting areas (remember, the background is always opaque).

Try this: Open the document you created earlier in this chapter. Create a new layer, and then use any painting tool to brush across the layer. Now, lower the Opacity setting in the Layers palette to 70%.

Now let’s compare this effect with what happens when you lower the Opacity setting of the Paintbrush tool. Create another new layer; however, this time leave the layer’s Opacity setting at 100%. Now choose the Paintbrush tool, change the tool’s Opacity setting to 70% (in the options bar), and then brush across the layer (just don’t overlap the paint you created earlier). The paint should look exactly the same as the paint that appears in the other layer.

Finally, create one more new layer, and paint across it with the tool’s Opacity setting at 100%. Now, brush across an area with the Eraser tool using an Opacity setting of 30%.

All of these options do the same thing to your image. You just have to think a bit: Do you want to apply the Opacity setting to the entire layer? If so, use the Layers palette’s Opacity setting. Do you want to apply the Opacity setting to only part of the layer? If so, use the Opacity setting in the tool’s options bar. Do you want to change the opacity of an area you’ve already painted across? If so, use the Eraser tool with an Opacity setting.

Adobe Photoshop always (well, almost always) offers you more than one way of doing things. It reminds me of my favorite hardware store, McGuckins. It’s the kind of place that takes your breath away—it has everything! If you just want a screwdriver, you’ll probably find an entire aisle full of screwdrivers, each one designed for a specific use. Photoshop has the same approach; you just have to play around with it to figure out which tool best suits your needs.

The eyeballs in the Layers palette determine which layers will be visible in your document as well as which ones will print. The eyeballs turn on and off in a toggle effect when you click them: Now you see them, now you don’t.

If you turn off all the eyeballs in the Layers palette, Adobe Photoshop will fill your screen with a checkerboard. This checkerboard indicates that there’s nothing visible in the document. (If Photoshop filled your screen with white instead, you might assume that there was a layer visible that was filled with white.) You can think of the checkerboard as the areas of the document that are empty. When you view a single layer, the checkerboard indicates the empty areas of that layer. As you turn on the other layers in the document, the checkerboard is replaced with the information contained on those layers. When multiple layers are visible, the checkerboard indicates where the underlying image will not be obstructed by the elements on the visible layers

The Background image in Photoshop (which some people refer to as the Background layer) is a bit different than the other layers that make up your image. If you liken the layers to the individual pages in a pad of tracing paper, you could think of the pad’s cardboard backing as the Background image. It might be the same size and it relates to the other pages in the pad, but it has some qualities that make it quite different.

The Background image has the same limitations as most of the common file formats in use today (such as JPEG and EPS): it’s always 100% opaque, no part of the background can extend beyond the document’s bounds, and it’s not actually considered a layer since most file formats don’t support layers (with a few exceptions such as .PSD and .TIFF formats). In fact, that’s the whole reason why the Background image exists. If all your document contains is the Background, then you should be able to save the image in just about any file format without losing information. That’s also why most images start life as a Background image—because they originated in a file format that didn’t support layers or came from a program that doesn’t support layers. When you save a layered document into a file format that doesn’t support layers (like JPEG), Photoshop will automatically combine all the layers that make up your image and turn the result into a Background image (known as flattening).

The Background image always displays a lock symbol to indicate that it cannot be repositioned with the Move tool, moved up or down in the layers stack, or be made transparent. For that reason, many tools will work differently when the Background image is active. For instance, the Eraser tool will paint with your Background color when the Background image is active since it is not able to make areas of the Background image transparent.

With all that said, you don’t actually have to have a Background in your document. If you want to convert the Background into a normal layer, just change its name (the Background image must be named “Background,” otherwise it becomes a normal, unlocked layer). To change the name of a layer, double-click the layer’s name in the Layers palette and type a new name.

Adobe Photoshop will automatically create the majority of the layers you’ll need. A new layer is added anytime you copy and paste an image or drag a layer between documents (we’ll talk about this later in the chapter). If you’re starting from scratch, however, you can click the New Layer icon at the bottom of the Layers palette to create a new, empty layer.

Give it a try: Choose File>New and create a document that is around 200 x 200 pixels in size with a transparent background (the resolution doesn’t matter at this point). Then, click the New Layer icon at the bottom of the Layers palette to create an empty layer. Next, click on your foreground color and pick out a bright color, choose the round Shape tool (it’s called an Ellipse and is grouped with the Rectangle Shape tool found below the Type tool in the Tools palette) and click on the rightmost icon of the three available in the upper left of the Options bar. Now, click and drag across your image to draw a big circle. Once you’re done with the first shape, create another layer and use the Rectangle Shape tool to draw a square on it, but with a different color. Finally, create a third layer and draw a triangle with yet another color (create the triangle by using the Polygon Shape tool with the Sides setting to 3 in the Options bar). You can use this simple document you’ve just created to try out the concepts in the following sections that describe the features of the Layers palette.

Note: I often create a new layer before using any of the painting tools or the Gradient tool. Because these tools apply changes directly to the active layer, the changes are difficult to modify once they’ve been applied. I like working with a safety net, so before using these tools, I create a new layer where I can easily edit the changes without disturbing the underlying

The Layers palette is like the mother everybody wanted as a teenager. Instead of yelling at you to clean your room, she patiently keeps track of all your stuff and she doesn’t care if you are neat and tidy, or an all-out slob. She is command central for everything you will ever do in Photoshop and the better you get to know her, the more you will be rewarded for your efforts. Whether you have just a few elements in your document, or hundreds, the Layers palette keeps everything organized, and gives you an amazing number of options for how to make the elements relate to each other. There’s no getting around this one; learning all the nooks and crannies and knowing how to use this palette effectively is absolutely essential to your success in Photoshop. The good news is that Layers—as opposed to some of Photoshop’s more complex features—is relatively easy territory to conquer. So the next time you have an urge to shout “Ma! Where are my blue socks?!”, take a look in the Layers palette, because you never know what you might find in there.

How Do Layers Work?

At first glance, layers might seem complex, but the idea behind them is rather simple. You isolate different parts of your image onto independent layers. These layers act as if they are separate documents stacked one on top of the other. By putting each image on its own layer, you can freely change your document’s look and layout without committing to the changes. If you paint, apply a filter, or make an adjustment, it affects only the layer on which you’re working. If you get into a snarl over a particularly troublesome layer, you can throw it away and start over. The rest of your document will remain untouched.

You can make the layers relate to each other in interesting ways, such as by poking holes in them to reveal an underlying image.

But first, you need to pick up on the basics—the foundations—of layers. If you’ve used layers for a while, you might find some of this chapter a bit too basic. On the other hand, you might find some juicy new tidbits.

Do you have a large .TIF or .PSD file with a lot of layers, but you only want to open a flattened version? No problem: hold down Option and Shift while double-clicking on the image in the File Browser. This works in the Open dialog box, too. Note that for .PSD files, this only works when the file was saved with a composite image. If, when you saved the file, you had turned off the Always Maximize Compatibility for Photoshop (PSD) Files option in the Preferences dialog box, you won’t be able to open the composite because there will be no composite to open (see “Preferences,” later in this chapter).

The first time you use the File Browser to view a folder of files, you’ll notice that it takes some time to gather information and build a thumbnail for each image. The next time you browse that folder, the images show up almost instantaneously. The trick? Photoshop saves the thumbnails in a cache—along with file information, ranking, and rotation setting. The cache is saved in a compressed and proprietary format on your local hard drive.

We thought this was all just fine and dandy until our colleague Deke McClelland pointed out two problems. First, if your images are on a network server, having rank and rotation information saved on your local hard drive doesn’t help anyone else who needs to see those images. Second, the cache references a specific folder name, so if you change the name of the folder, all the thumbnails, ranking, and so on, are lost.

Fortunately, Photoshop lets you save a folder’s cache file within the folder itself. To do this, select Export Cache from the File Browser’s popout menu. When the exported cache files (which are called AdobePS7.tb0 and AdobePS7.md0) are present in a folder, Photoshop uses them instead of creating new cache files.

If you later write the folder full of images to a CD, Photoshop can even read the cache off the CD. However, any subsequent changes you make to the rankings or image rotation are only stored in your local cache (not on the CD, as it is read-only).

Most digital cameras assign names like P0001924.JPG to each image. Is that useful to anyone? If you have a folder full of these kinds of files, the File Browser can rename them all. First, make sure no thumbnails are selected in the File Browser. Then, choose Batch Rename from the File Browser’s popup menu. Photoshop displays the Batch Rename dialog box, which gives you a number of options for naming files. Careful with this one; you can’t undo it after clicking OK.

Jump to File by Name. If your folder has dozens of images in it, it’s a hassle to use the scroll bars in the File Browser. Instead, just click on any image in the File Browser window and then type the first few letters of the name of the image you’re looking for. You can also use the arrow keys to move around this window.

If you’re like us, you’ve got way too many images floating around on various disks, and finding the right image at the right time can be a hassle. Fortunately, Adobe Photoshop has made this process a giant step easier with the File Browser window, which acts like an Open dialog box on steroids . You can browse through the images on your disk, create folders, move images in and out of folders, rename files, or even delete images from disk.

You can also tell the File Browser to rotate images. In this case, the image on disk isn’t actually changed. Instead, the File Browser itself remembers to rotate the image as soon as you open it inside Photoshop. You can select more than one image at a time in the File Browser window by Shift-clicking (for contiguous selections) or Command-clicking (for selections that aren’t next to each other).

Rank and File. You can change a file’s name by clicking on it in the File Browser (or select the image and press Enter). This actually changes the file name on disk. You can also change a file’s Rank by clicking in the Rank area (which is only visible when you have the File Browser set to “Large with Rank” view). Rank is simply an additional way of ordering images. For instance, if you take five snapshots of a model, you can rank them in the order of preference for easy reference later. Then, to view all the “A” ranked images, you could select Rank from the Sort By popup menu at the bottom of the File Browser window.

Note that you can jump from one file name field to the next by typing Tab (or back to the previous file name field with Shift-Tab). Similarly, if you’re editing a Rank field, you can jump the next or previous image’s Rank field with Tab or Shift-Tab.