Essential Photoshop Tips and Tricks

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Adding More Noise. If you're still getting banding even with Dither turned on, you may want to add even more noise to a blend. However, note that you don't always need to apply the Add Noise filter to the entire gradient; use the filter selectively.

Instead, you might find it better to add noise to only one or two channels. View each channel separately (see Chapter 13, Selections) to see where the banding is more prevalent. Then add some noise just to the blend area in that channel.

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Blends in CMYK. Eric Reinfeld pounded it into our heads one day: if you're going to make blends in Photoshop images that will end up in CMYK mode, create them in CMYK mode. Sometimes changing modes from RGB to CMYK can give you significant color shifts in blends.

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Gradients on Layers. Some people make hard work of creating a blend that fades away into transparency. They go through endless convolutions of Layer Masks and Channel Options, or they spend hours building custom gradients, and so on. They're making it difficult for themselves by not opening their eyes. When you have the Gradient tool selected, the Options bar offers a popup menu with various gradients in it, and one of the defaults blends from Foreground to Transparent, or from Transparent to Foreground. If that option isn't available, someone may have edited your gradient presets. You can create or edit a gradient by clicking once on the gradient swatch in the Options bar. You can also select a different set of gradient presets from the popout menu to the right of the swatch (see Figure 2-13).

Figure 2-13 Gradient options

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Brush Keystrokes. Did you know that the [ and ] keys (the square brackets) increase and decrease the diameter of a brush? Plus, Shift-[ and Shift-] change the brush's hardness. We now keep one hand on the keyboard and one on our mouse (or tablet pen); when we want to change tools, we press the key for that tool. When we want to change brush size, we cycle through the brushes with the [ and ] keys until we find the size we like. Here's one more shortcut, too: the Command and period keys move up and down through the brush presets.

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Fastest Brush Selection. Actually, one of the best ways to select a brush is probably via the context-sensitive menu. On the Macintosh, hold down the Control key when you click with any of the painting tools and Photoshop displays the Brushes menu wherever you click. In Windows, right-mouse-button-click to see the menu. After selecting a brush size, press Enter to make the palette disappear.

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Hovering Pseudo-Selections. Instead of selecting a brush from the Brushes palette, then painting with it to see how it will really look, hover the cursor over the preset for a moment and Photoshop will display a sample of that brush at the bottom of the palette. If you don't like it, hover over another brush. When you find one you like, click on it to select it.

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Opacity by the Numbers. In between changing brush sizes, we're forever changing brush opacity while painting or retouching. If you're still moving the sliders around on the Options bar, stop it. Instead, just type a number from 0 to 9. Zero gives you 100-percent opacity, 1 gives you 10 percent, 2 gives you 20 percent, and so on. For finer control, press two number keys in quick succession—for example, pressing 45 gets you 45-percent opacity. If you have a non-painting tool selected in the Tool palette, then typing a number changes the opacity of the layer you're working on (unless it's the Background layer, of course). Note that if the Airbrush feature in the Options bar is turned on, then typing numbers affects the Flow percentage rather than the Opacity setting.

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Touching Up Line Art. We talk about scanning and converting to line art in Chapter 11, Line Art, but since we're on the topic of painting tools, we should discuss the Pencil tool for just a moment. One of the best techniques for retouching line-art (black-and-white) images is the Auto Erase feature on the Options bar. When Auto Erase is turned on, the Pencil tool works like this: if you click on any color other than the foreground color, that pixel—along with all others you touch before lifting the mouse button—is changed to the foreground color (this is the way it works, even with Auto Erase turned off). If you click on the foreground color, however, that pixel—along with all others you encounter—is changed to the background color.

This effectively means you don't have to keep switching the foreground and background colors while you work.

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Use All Layers. If you're working on a multilayer image, you may find yourself frustrated with tools like the Smudge, Blur, Magic Wand, or the Clone Stamp tools. That's because sometimes you want these tools to "see" the layers below the one you're working on, and sometimes you do not. Fortunately, Photoshop gives you a choice for each of these tools with the Use All Layers checkbox on the Options bar. (Note that in older versions, this was called Sample Merged.) When Use All Layers is turned off, each tool acts as though the other layers weren't even there. But if you turn it on, look out! Photoshop sees the other visible layers (both above and below it) and acts as though they were merged together (see Figure 2-15).

Figure 2-15 Use All Layers

The benefit of this is great, but people often don't see the downfall. Let's say your background contains a blue box, and Layer 1 has an overlapping yellow box. When you paint or smudge or blur or whatever with Use All Layers turned on, Photoshop "sucks up" the blue and paints it into Layer 1. If you think about it, that's what it should and has to do. But it can really throw you for a loop if you're not prepared.

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Painting in High-Bit Files. You may have noticed that the Brush tool doesn't work on high-bit files (files set to 16-bits per channel in the Mode submenu, under the Image menu). But the History brush does. You can paint on any high-bit file by first editing the file to get the color you want (we usually use Curves, and start by pulling the zero point up to level 255 to turn the whole image white, then we use individual channel curves with straight horizontal lines to obtain the color percentages we want). Next, create a New Snapshot of the solid color. Then go to the History palette, step back to the image state before you made the solid color, and set the Snapshot you made in the previous step as the source for the History brush. Presto! You can paint any color into the high-bit image.

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See What Gets Cropped. By default, Photoshop darkens the area outside the cropping rectangle so that you can see what's going to get cropped out before you press Enter. However, David likes to change this behavior so that it ghosts the cropped out pixels instead (turns them near white). You can do this by clicking on the Color swatch in the Options bar (when the Cropping tool is selected) and picking white from the Color Picker instead of black. You may want to increase the opacity of the color in the Options bar, too (David usually uses 80 percent).

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Rotating and Moving While Cropping. If cropping an image down is the most common postscan step, what is the second most common? Rotating, of course. You can crop and rotate at the same time with the Cropping tool: after dragging out the cropping rectangle with the Cropping tool, just place the cursor outside the cropping rectangle and drag. The rectangle rotates. When you press Return or Enter, Photoshop crops and rotates the image to straighten the rectangle. It can be tricky to get exactly the right angle by eye—keep an eye on the Info palette. Also, if the cropping rectangle isn't in the right place, you can always move it—just place the cursor inside the cropping rectangle and drag.

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Adjusting for Keystone. What do you do about lines in your image that are supposed to be vertical or horizontal but aren't? For example, if you take a picture of a tall building from the sidewalk, the vertical lines of the building appear skewed (they look like they get closer together near the top). Fortunately, our faithful Cropping tool offers a cool option: adjusting for perspective. The key is to turn on the Perspective checkbox in the Options bar after drawing the cropping rectangle; this lets you grab the corner points and move them willy-nilly where you will.

However, positioning the corner points of the cropping "rectangle" can be tricky. You must first find something in the image that is supposed to be a rectangle, and set the corner points on the corners of that shape. In the example of a building, you might choose the corners of a window. Then, hold down the Option and Shift keys while dragging one of the corner handles; this expands the crop but retains its shape. When you have the cropping shape the size you want it, drag the center point icon to where the camera was pointing (or where you imagine the center of the focus should be). Then press Enter or Return.

Our favorite use for this technique is photographing framed paintings (or anything hanging on the wall). If you shoot the painting straight-on (especially with a flash), you get a nasty reflection. Instead, try photographing it slightly from one side. The image becomes distorted by this perspective, but this Perspective feature can quickly straighten it out (see Figure 2-16).

By the way, we find that when using this tool Photoshop often alerts us that either the center point or the corner points are in the wrong position. This usually happens when you haven't selected the corner points of something that should be rectangular. In other words, Photoshop acts as a safety net, stopping you when you choose a distortion that isn't likely to happen in a real photograph. Sometimes simply moving the center point to a different location (by trial and error) does the trick.

Figure 2-16 Adjusting perspective with the Crop tool

Save that Layer Data. In early versions of Photoshop, the cropping tool would throw away pixels outside the cropping rectangle. If you changed your mind and wanted to crop the image differently, you would have to select Undo and then try again. But Photoshop now gives you the option (by selecting the Hide button in the Options bar after dragging the cropping rectangle) of saving the cropped-out pixels as big data—material that hangs outside the actual visible image rectangle. Then, if you didn't get the crop just right, you can either move the image around with the Move tool or re-crop using a different rectangle (see "Expand the Canvas by Cropping," later in this chapter). Note that this only works on layers other than the Background layer.

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Resampling While Cropping. Warning: the Cropping tool may be changing your resolution or even resampling your image data without you knowing it! The Height, Width, and Resolution fields in the Options bar (when you have the Cropping tool selected) let you choose a size and resolution for your cropped picture. Basically, these fields let you save the step of visiting the Image Size dialog box after cropping. But remember that when you use them, they always change your image resolution or resample the image (see Chapter 3, Image Essentials, for more on the pros and cons of resampling).

In ancient versions of Photoshop, if you left the Resolution field blank and you specified a Height and Width without specifying any units (like pixels, inches, and so on), the program would constrain the cropping size to a particular aspect ratio (like four-by-six) but it wouldn't mess with your resolution. Alas, now the Height and Width fields always have units attached to them. If you leave the Resolution field blank, Photoshop adjusts the image resolution to accommodate the change in size. That means your image resolution can go way down without you realizing it. Instead, see the next tip for how to crop to an aspect ratio.

If you type a value into the Resolution field, Photoshop resamples the image to that value. This resampling behavior is handy when you want to resample down, but be careful that you don't ask for more resolution than you really have; resampling up is best avoided. (Note that you can only set the Height, Width, and Resolution values before you start cropping; once you draw a cropping rectangle, the Options bar changes.)

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Cropping to an Aspect Ratio. Let's say you want to crop your image to a four-by-six aspect ratio (height-to-width, or vice versa), but you don't want to resample the image (which adds or removes pixels, causing blurring). The Cropping tool can't perform this task anymore, so you need a different technique. First, select the Marquee (rectangular selection) tool and choose Constrained Aspect Ratio from the Style popup menu in the Options bar. The Options bar then lets you type values in the Height and Width fields (here you'd type 4 and 6). Next, marquee the area you want cropped, and then select Crop from the Image menu. See Chapter 13, Selections, for tips and tricks for the Marquee tool.

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Expand the Canvas by Cropping. Once you've created a cropping rectangle with the Cropping tool, you can actually expand the crop past the boundaries of the image (assuming you zoom back until you see the gray area around the image in the document window). Then, after you press Enter, the canvas size actually expands to the edge of the cropping rectangle. This is David's favorite way to enlarge the canvas.

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Cropping Near the Border. If you're trying to shave just a sliver of pixels off one side of an image, you'll find it incredibly annoying that Photoshop snaps the cropping rectangle to the edge of the image whenever you drag close to it. Fortunately, you can turn this behavior off by selecting Snap in the View menu (or pressing Command-Shift-;). Or, you can hold down the Control key to temporarily disable the snapping behavior.

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Erase to History. The Erase to History feature (it's a checkbox on the Options bar when you have the Eraser tool selected) lets you use the Eraser tool to replace pixels from an earlier state of the image (see "When Things Go Worng," later in this chapter, for more on the History feature). Erase to History more or less turns the Eraser into the History Brush tool. For instance, you can open a file, mess with it until it's a mess, then revert parts of it to the original using the Eraser tool with Erase to History turned on.

The important thing to remember is that you can temporarily turn on the Erase to History feature by holding down the Option key while using the Eraser tool.

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Watch Preserve Transparency When Erasing. Note that the Eraser tool (or any other tool, for that matter) won't change a layer's transparency when you have the Preserve Transparency checkbox turned on in the Layers palette. That means it won't erase pixels away to transparency; rather it just paints in the background color. Don't forget you can turn Preserve Transparency on and off by pressing / (slash).

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Erasing to Transparency. When you use a soft-edged brush to erase pixels from a layer (rather than the Background layer), the pixels that are partially erased—that is, they're still somewhat visible, but they have some transparency in them—cannot be brought back to full opacity. For example, if you set the Eraser to 50-percent opacity and erase a bunch of pixels from a layer, there's no way to get them back to 100-percent again. The reason: You're not changing the pixel's color, you're only changing the layer's transparency mask. This isn't really a it's just a warning. What you erase sometimes doesn't really go away.

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Measuring Before Rotating. We know you always make sure your images are placed squarely on the scanner before you scan them, but you may occasionally have to level someone else's crooked scan. Again, the Measurement tool can help immensely. If you select Arbitrary from the Rotate Canvas submenu (under the Image menu) immediately after using the Measurement tool, Photoshop automatically grabs the angle and places it in the dialog box for you.

There are two things to note here. First, the angle in the Rotate Canvas dialog box is usually slightly more accurate, so the number you see there may be slightly different from the one on the Info palette (usually within half a degree). Second, if the angle is above 45 degrees, Photoshop automatically subtracts it from 90 degrees, assuming that you want to rotate it counterclockwise to align with the vertical axis instead of the horizontal axis.

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Move the Notes Away. By default, Photoshop places your notes windows at the same place in your image as the Notes icon. However, that means the little notes window usually covers up the image so you can't see what the note refers to. We usually drag the Notes icon off to the side slightly (just click and drag the note's title bar to move it), or—if there aren't many notes in a file—most of the way off the image, onto the gray area that surrounds the picture.

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Show the Notes. If you can't see notes in your Photoshop file but you suspect they're there, make sure the Annotations item is turned on in the Show submenu (under the View menu). When this is off, no Notes icons appear.

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Make the Palettes Go Away. If you only have one monitor on which to store both your image and Photoshop's plethora of palettes, you should remember two keyboard shortcuts. First, pressing Tab makes the palettes disappear (or reappear, if they're already hidden). We find this absolutely invaluable, and use it daily. Second, pressing Shift-Tab makes all palettes except the Tool palette disappear (or reappear). We find this only slightly better than completely useless; we would prefer that the keystroke hid all the palettes except the Info palette.

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Making Palettes Smaller. Another way to maximize your screen real estate is by collapsing one or more of your open palettes. If you double-click on the palette's name tab, the palette collapses to just the title bar and name (see Figure 2-18). Or if you click in the zoom box of a palette (the checkbox in the upper-right corner of the palette), the palette reduces in size to only a few key elements. For instance, if you click in the zoom box of the Layers palette, you can still use the Opacity sliders and Mode popup menu (but the Layer tiles and icons get hidden).

Figure 2-18 Collapsing palettes

Mix and Match Palettes. There's one more way to save space on your computer screen: mix and match your palettes. Palettes in Photoshop have a curious attribute—you can drag one on top of another and they become one (see Figure 2-19). Then if you want, you can drag them apart again by clicking and dragging the palette's tab heading. (In fact, these kinds of palettes are called "tabbed palettes.")

Figure 2-19 Mixing and matching palettes

For instance, David always keeps his Layers, Channels, and Paths palettes together on one palette. When he wants to work with one of these, he can click on that palette's tab heading. Or better yet, he uses a keystroke to make it active (see "Actions" in Chapter 14, Essential Image Techniques, for more on how to define your own keyboard shortcuts).

Bruce, on the other hand, always keeps his Layers and Channels palettes separate, even when he's working on a single-monitor system. Neither of us ever mixes the Info palette with another palette, because we want it open all the time.

Photoshop offers one more way to combine palettes: by docking them. Docking a palette means that one palette is attached to the bottom of another one. Docked palettes always move together, and when you hide one they both disappear. To dock one palette to another, drag it over the other palette's bottom edge; don't let go of the mouse button until you see the bottom edge of the palette become highlighted.

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In-and-Out Palettes. You can store palettes in the Options bar as well: when your screen resolution is above 800 pixels wide, the Options bar contains a "palette well," onto which you can drag palettes. Then, to use one of these palettes, just click on its tab. When you press Enter or Return, or as soon as you start doing anything else (like use a tool or a menu), the palette minimizes into the well again. This behavior is perfect for the Swatches and Colors palettes, but is inappropriate for palettes you need open a lot, like the Info or Layers palettes.

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Reset Palette Positions. Every now and again, your palettes might get really messed up—placed partly or entirely off your screen, and so on. Don't panic; that's what Reset Palette Locations (in the Workspace sub-menu, in the Window menu) is for. In earlier versions, this feature was hidden as a button labeled "Reset Palette Locations to Default" in the Preferences dialog box.

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Save Info Palette Configurations. If you're like us, you probably use different info palette setups for different kinds of work. For example, when Bruce works on RGB files destined for CMYK output, he sets one readout to RGB and the other to CMYK. But if he's working on RGB files for RGB output on an inkjet or film recorder, he sets the Info palette to read RGB and Lab. When you save a workspace, it records not only palette locations, but also the Info palette configuration, so you can use workspaces to switch easily between different Info palette setups.

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Displaying Multiple Layers. Every click takes another moment or two, and many people click in the display column of the Layers palette (the one with the little eyeballs in it) once for each layer they want to see. Cut out the clicker-chatter, and just click and drag through the column for all the layers you want to see.

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Click to Turn Off Layers. Another way to make multiple layers appear or disappear is by Option-clicking in the display column of the Layers palette. When you Option-click on an eyeball, Photoshop hides all the layers except the one you clicked on. Then, if you Option-click again, it redisplays them all again. Even though this trick doesn't save you a lot of time, it sure feels like it does (which is often just as cool).

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Creating a New Layer. Layers are the best thing since sliced bread, and we're creating new ones all the time. But if you're still making a new layer by clicking on the New Layer button in the Layers palette, you've got some learning to do: Just click Command-Shift-N (or Command-Option-Shift-N, if you don't want to see the New Layer dialog box). If you're trying to duplicate the current layer, just press Command-J (if you have pixels selected when you press this, only those pixels will copy to a new layer).

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Rename your Layers. It's a very good idea to rename your layers from Layer 1 or Layer 2 to something a bit more descriptive. However, don't waste time looking for a "rename layer" feature. Instead, just double-click on the layer tile to rename it. Note that this works in the Channels, Paths, and File Browser palettes, too.

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Creating Layer Sets. The more layers you have in your document, the more difficult it is to manage them. Fortunately, Photoshop now offers layer "sets" in which you can group contiguous layers (layers that are next to each other). Layer sets are so easy to use that they really don't require a great deal of explanation. Here are the basics, though.

• To create a layer set, click on the New Layer Set button in the Layers palette (see Figure 2-21).

  Figure 2-21 Layer sets

  
  

• To add a layer to a set, just drag it on top of the set. Or, to create a new layer inside the set automatically, select the set or any layer within the set (in the Layers palette) and press the New Layer button. You can remove a layer from a set simply by dragging it out.

• You can move layer sets in the same way you move layers: just drag them around in the palette. You can also copy a whole set of layers to a different document by dragging the layer set over.

• If you have more than one layer set, it's helpful to color code them: just double-click on the layer set's name and pick a color in the Layer Set Properties dialog box. You should probably name the set, too, while you're there (the default "Set 1" doesn't help identify what's in it).Watch out, though: if you drag a color-coded layer out of the set, it still retains its color-coding!

• If you want to move all the layers within a layer set at the same time, select the layer set in the Layers palette. This is easier and faster than linking the layers together.

• You can add a layer mask to the layer set (see Chapter 13, Selections for more on masks) and it'll apply to every layer in the set. Similarly, locking a set locks every layer within the set.

• Layer sets act almost like a single layer, so when you show or hide the set, all the layers in that set appear or disappear.

• When you delete a layer set, Photoshop lets you choose to delete the set and the layers inside it or just the set itself (leaving the layers intact).

Unfortunately, you can't apply a layer effect (see Chapter 14, Essential Image Techniques) to a set or use a set as a clipping group (see Chapter 13, Selections).

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Layer Sets and Blending Modes. If you had your coffee this morning, you'll notice that you can change the blending mode of a layer set. Normally, the blending mode is set to Pass Through, which means, "let each layer's blending mode speak for itself." In this mode, layers inside the set look the same as they do if they were outside the set. However, if you change the set's blending mode, a curious thing happens: Photoshop first composites the layers in the set together as though they were a single layer (following the blending modes you've specified for each layer), and then it composites that "single layer" together with the rest of your image using the layer set's blending mode. In this case, layers may appear very different whether they're inside or outside that set.

Similarly, when you change the opacity of the set, Photoshop first composites the layers in the set together (using their individual Opacity settings) and then applies this global Opacity setting to the result.

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Finding Opacity. When you have transparency showing (e.g., on layers that have transparency when no background is showing), the Info palette can give you an opacity ("Op") reading. However, while Photoshop would display this automatically in earlier versions, now you have to do a little extra work: you must click on one of the little black eyedroppers in the Info palette and select Opacity (see Figure 2-22).

Figure 2-22 The Info palette

Switch Units. While we typically work in pixel measurements, we do on occasion need to see "real world" physical measurements such as inches or centimeters. Instead of traversing the menus to open the Units dialog box (on the Preferences submenu under the File menu), we find it's usually faster to select from the Info palette's popout menus. Just click on the XY cursor icon (see Figure 2-23). Another option: double-clicking in one of the rulers opens the Units Preferences dialog box. Note that you can also do this by Control-clicking (on the Mac) or Right-button-clicking (in Windows) on one of the rulers. (Press Command-R if the rulers aren't visible.)

Figure 2-23 Changing units

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Switching Color Bars. Instead of clicking on the foreground color swatch in the Tool palette, you might consider typing values into the Color palette. Are the fields labeled "RGB" when you want to type in "CMYK" or something else? Just choose a different mode from the popout menu on the palette. If you like choosing colors visually rather than numerically, you can use the color bar at the bottom of the palette (no, the Color Bar is not just another place to meet people). While the spectrum of colors that appear here usually covers the RGB gamut, you can switch to a different spectrum by Shift-clicking on the area. Click once, and you switch to CMYK; again, and you get a gradient in grayscale; a third time, and you see a gradient from your foreground color to your background color. Shift-clicking again takes you back to RGB.

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Editing the Color Swatches. You've probably ignored all those swatches on the Swatches palette because they never seem to include colors that have anything to do with your images. Don't ignore... explore! You can add, delete, and edit those little color swatches on the Swatches palette. Table 2-2 shows you how. If you're looking for Web-safe colors, or other useful colors, check out the popout menu at the top of the palette.

You can't actually edit a color that's already there. Instead, you can click on the swatch (to make it the current foreground color), edit the foreground color, then Shift-click back on the swatch (which replaces it with the current foreground color).

Table 2-2 Editing the Swatches palette

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Turn Each Way. To flag one or more selected images for rotation, click on the Rotate button in the lower-right corner of the File Browser window. Each click rotates the image 90 degrees clockwise. If you want to rotate counter-clockwise, Option-click the button. You can also rotate an image by Control-clicking (Mac) or right-button-clicking (Windows) on an it and selecting Rotate from the context-sensitive menu.

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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 (see Figure 2-25).

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.

Figure 2-25 View By Rank

Renaming a Folder. 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 (see Figure 2-26). Careful with this one; you can't undo it after clicking OK.

Figure 2-26 Batch Rename

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.

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Copying Images. You can move files from one folder into another by dragging the file's thumbnail into any other folder in the navigation area of the File Browser. Add the Option key and the file is copied instead of moved.

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Exporting the Cache. 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 (see Figure 2-27). 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.

Figure 2-27 The File Browser popout menu

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).

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Purge the Cache. Photoshop builds a cache for every folder you open in the File Browser. If you're looking at images all day, the cache will grow to take up an enormous amount of hard drive space. That's why it's a good idea to empty the cache folder every month or so by selecting Purge Cache from the File Browser's popout menu. Of course, this will delete all the ranking and rotation settings, too, which could be disastrous, depending on your workflow.

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Opening the Composite. 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).

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Expanded File Browser. To maximize the thumbnail view on the right side of the File Browser and hide the navigation view, click on the Expanded View button at the bottom of the File Browser window—that's the little button with the double-headed arrow. Or, note that you can also just expand the File Browser window to any size you want and then move the borders between each section of the window by dragging them. For example, if you want more space to display the additional file information, you can just click-and-drag the border area between it and the thumbnail preview.

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Close the Browser. You can leave the File Browser open all the time as a free-floating window, but we don't recommend it. When open, the File Browser is constantly working in the background and it will slow you down. Instead, it's best to put it into the Options Bar's palette well and just open it when you need it. To do this, select Dock to Palette Well from the File Browser's popout menu.

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Return of Preferences. If you make a change in one of the many Preferences dialog boxes and then—after pressing OK—you decide to change to some other preference, you can return to the same dialog box by pressing Command-Option-K.

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Navigating Through Preferences. The Preferences dialog box contains eight different "screens" or "tabs," each of which offers a different set of options (see Figure 2-28). Sure, you can select each screen from the popup menu at the top of the dialog box, or by clicking the Next and Prev buttons. But the fastest way to jump to a particular screen is by pressing Command-1 (for the first screen), Command-2 (for the second screen), and so on up to Command-8.

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Propagating your Preferences. Any time you make a change to one of the Preferences dialog boxes, Photoshop remembers your alteration, and when you quit, saves it in the "Adobe Photoshop 7.0 Prefs" file. (In Mac OS 9.x, this is in the System Folder>Preferences>Adobe Photoshop 7 folder. In Mac OS X, it's in User>YourName>Library>Preferences> Adobe Photoshop 7 Settings. On Windows systems, it's in the Windows> Application Data>Adobe>Photoshop>7.0>Adobe Photoshop 7.0 Settings directory.) If anything happens to that file, all your changes are gone. Because of this, we recommend keeping a backup of that file, or even the whole settings directory (people often back up their images without realizing they should back up this sort of data file, too).

Certain kinds of crashes (mostly caused by software other than Photoshop) can corrupt Photoshop's Preferences file. If Photoshop starts acting strange on us, our first step is always to replace the Preferences file with a clean copy (if no copy of the Preferences file is available, then Photoshop will build a new one for you).

Note that if you administer a number of different computers that are running Photoshop, you may want to standardize the preferences on all machines. The answer: copy the Photoshop Prefs file to each computer. Finally, note that Photoshop doesn't save changes to the preferences until you Quit. If Photoshop crashes, the changes don't get saved.

Figure 2-28 General Preferences dialog box

Export Clipboard. When the Export Clipboard checkbox is on, Photoshop converts whatever is on the clipboard into a PICT or WMF format when you leave Photoshop. This is helpful—indeed, necessary—if you want to paste a selection into some other program. But if you've got a megabyte or two or 10 megabytes on the clipboard, that conversion is going to take some time. In situations when you're running low on RAM, it may even crash your machine, though this is now rare. We recommend leaving Export Clipboard off until you really need it.

Dynamic Color Sliders. This one is pretty subtle. When Dynamic Color Sliders in the Picker is turned on, the bars for the sliders on the Picker palette change color as you drag. The target color changes as you drag, whether it's turned on or not—it just affects the sliders themselves. We tend to leave this one turned on.

Save Palette Locations. This does what it says—it remembers which palettes were open, which were closed, and where they were located on the screen the last time you quit. But if you change your monitor resolution, the palettes return to their default locations. We leave this turned on.

Use System Shortcut Keys. In Mac OS X, Apple appropriated two keyboard shortcuts that were crucial for Photoshop users: Command-H and Command-M. Photoshop users know these as "Hide Selection" and "Curves dialog box." The Mac OS X folks use these shortcuts for "Hide Application" and "Minimize Application." Fortunately, the folks at Adobe give us an option. By default, the old Photoshop keystrokes win. However, if you turn on the Use System Shortcut Keys option, Photoshop defers to the OS X features.

But wait, there's more: If you hold down the Control key, you get the opposite result. That is, when Use System Shortcut Keys is turned off, you can press Command-Control-H to get Hide Application, and so on.

Image Previews. When you save a document in Photoshop, the program can save little thumbnails of your image as file icons. These thumbnails can be helpful, or they can simply be a drag to your productivity. We always set Image Previews to Ask When Saving, so we get a choice for each file (see "Preview Options" in Chapter 15, Storing Images).

Ask Before Saving Layered TIFF Files. Most people don't realize that TIFF files can include Photoshop layers. We discuss this in detail in Chapter 15, Storing Images, but we should point out one thing here: When the Ask Before Saving Layered TIFF Files option is turned on in Preferences (it is by default), Photoshop will always alert you when you try to save a file that was a flat (non-layered) TIFF but now has layers. For example, if you open a TIFF image and add some type, the text shows up on a type layer. Now if you press Command-S to save the file, Photoshop displays the TIFF Options dialog box, in which you can either flatten the layers or keep them.

If you find yourself staring at this dialog box too much, and you keep thinking to yourself, "If I wanted to flatten the image, I would have done it myself," then go ahead and turn this option of in the Preferences dialog box. Then Photoshop won't bother you anymore. Personally, we like this option and we leave it turned on.

Always Maximize Compatibility for Photoshop (PSD) Files. We used to think that the Always Maximize Compatibility for Photoshop (PSD) Files feature (previously known as "Maximize Backwards Compatibility in Photoshop Format," "Include Composited Image with Layered Files," or "2.5 Format Compatibility") was completely brain-dead. Now we think it's only "mostly useless." Basically, when this checkbox is turned on, Photoshop saves a flattened version of your layered image along with the layered version. The result: if you give the file to someone who is using Photoshop 2.5 (we don't know anyone who does), they can open it. Of course, if they do anything to the file and resave it, then all your layers are deleted. Not very helpful.

The main problem is that this feature (which is on by default) makes your image sizes larger on disk (sometimes several times larger) than they would otherwise be.

We've always said: turn this off and leave it off. However, there are two very good exceptions. First, leave it turned on if you're using some other program that claims to open native Photoshop files, like Macromedia FreeHand, but which requires this flattened version to work. A second reason to leave it on is that future versions of Photoshop may interpret blending modes slightly differently than they do today. Adobe won't say what might change (or even if there will be changes), but if they do change something, and that change affects the look of your file, then you would at least be able to recover the flattened version if there is one. That said, we would still rather leave this option turned off, and just keep an archived, flattened version of color-critical images. We discuss this in more detail in Chapter 15, Storing Images.

Diffusion Dither. If, for some bizarre reason, your monitor is set to 8-bit color (we hardly ever work with Photoshop in less than "Thousands" of colors), Photoshop has to do even more work at displaying its plethora of colors on your screen. This is usually done with dithering of some sort. You can choose the method: when Use Diffusion Dither is turned on in the Display & Cursors Preferences dialog box, Photoshop generates colors using a "random" pixel placement. Otherwise, it uses a standard pattern. Neither of these methods is all that attractive, though Diffusion Dither often produces a nicer look when zoomed in closer than 1:1.

Brush Size. When you painted or edited pixels in pre-3.0 versions of Photoshop, the program would display the cursor only as a Brush icon (or Clone Stamp icon, or whatever you were using). Because it was often difficult to tell which pixel the tool would affect, Photoshop implemented the handy crosshairs feature—when Caps Lock is down, the cursor switches to a crosshair icon displaying precisely which pixel Photoshop is "looking at." But most brushes affect more than one pixel at a time, so now when you set Painting Cursors to Brush Size (in the Display & Cursors Preferences dialog box), Photoshop shows you exactly how large the brush is while you're painting or editing (see Figure 2-29). After working with this for a while, you'll wonder how you could ever go back. You can still get the crosshairs with the Caps Lock key.

Figure 2-29 Brush Size

Gamut Warning. Bruce thinks the Gamut Warning is basically useless—he'd rather just see what's happening to the out-of-gamut colors when they're converted—but for the record, when you turn on Gamut Warning from the View menu (or press Command-Shift-Y), Photoshop displays all the out-of-gamut pixels in the color you choose here. (For more on Photoshop's out-of-gamut display features, see "Gamut Alarm" in Chapter 7, Color Correction.) If you do want to use this feature (David likes it), we recommend you choose a really ugly color (in the Transparency & Gamut Preferences dialog box) that doesn't appear anywhere in your image, such as a bright lime green. This way, when you switch on Gamut Warning, the out-of-gamut areas are quite obvious.

Transparency. Transparency is not a color, it's a state of mind. Therefore, when you see it on a layer, what should it look like? Typically, Photoshop displays transparency as a grid of white and gray boxes in a checkerboard pattern. The Preferences dialog box lets you change the colors of the checkerboard and set the size of the squares, though we've never found a reason to do so (see Figure 2-30).

Figure 2-30 Transparency Preferences

Legacy Photoshop Serial Number. Photoshop 7 has an all-new serial number scheme—old serial numbers won't work. This could create problems if you want to use third-party plug-ins whose copy-protection serializes them to your old Photoshop serial number, so Photoshop lets you enter your old serial number in the Plug-ins & Scratch Disk tab of the Preferences dialog box. Your old plug-ins can then find the serial number they're expecting, and run happily in the new version. (Of course, they still won't work if you're running in Mac OS X and the plug-ins aren't designed for that operating system.)

Image Cache. Adobe has been getting yelled at for years about Photoshop's handling of large images. Finally, in version 4, Photoshop introduced a nominal concession towards large-image handling with the Image Cache feature. It wasn't a great step forward, but it was a step nonetheless (Photoshop 7 hasn't progressed any farther down the road). When Image Cache is on (as it is by default), Photoshop saves several downsampled, low-resolution versions of your image. That way, if you work on your image in a zoomed-out view, Photoshop can update your screen preview more quickly by displaying the cached image instead of downsampling the full-resolution one.

If you're low on RAM, you should probably turn off image caching (set the number of caches to 1 in the Image Cache Preferences dialog box; see Figure 2-31), because these downsampled versions of your image take up extra RAM (or space on your scratch disk, if you don't have enough RAM available). If you've got plenty of RAM and you spend a lot of time working at zoom percentages less than 100 percent, an Image Cache setting of 4 or higher could help speed you up. Each cache level caches one increment of zoom, so a setting of 4 caches the 66.7-, 50-, 33.3- and 25-percent views, while a setting of 6 adds the 16.7-percent and 12.5-percent views. The highest setting, 8 levels, caches all views down to 6.25 percent. This is really only useful on very large images, but the incremental difference in RAM footprint between 6 levels and 8 levels is so small that even if you'd benefit from a setting of 8 only occasionally, you'd probably be best off just setting the Image Cache to 8 and leaving it there.

Figure 2-31 Image Cache Preferences

Note that we strongly urge you to keep the "Use cache for histograms" checkbox in this Preferences dialog box turned off. While turning it on will speed up your histograms at views other than 100 percent, it renders these histograms useless (see "Turn Off Use Image Cache For Histograms" in Chapter 6, Tonal Correction).

When Things Go Worng

It's 11 PM on the night before your big presentation. You've been working on this image for thirteen hours, and you're beginning to experience a bad case of "pixel vision." After making a selection, you run a filter, look carefully, and decide that you don't like the effect. But before you can reach Undo, you accidentally click on the document window, deselect-ing the area.

That's not so bad, is it? Not until you realize that undoing will only undo the deselection, not the filter... and that you haven't saved for half an hour. The mistake remains, and there's no way to get rid of it without losing the last 30 minutes of brain-draining work. Or is there? In this section of the chapter, we take a look at the various ways you can save yourself when something goes terribly wrong.

Undo. The first defense against any offensive mistake is, of course, Undo. You can find this on the Edit menu, but we suggest keeping one hand conveniently on the Command and Z keys, ready and waiting for the blunder that is sure to come sooner or later. Note that Photoshop is smart enough not to consider some things "undoable." Taking a snapshot, for instance, doesn't count; so you can take a snapshot and then undo whatever you did just before the snapshot. Similarly, you can open the Histogram, hide edges, change foreground or background colors, zoom, scroll, or even duplicate the file, and Photoshop still lets you go back and undo the previous action.

Revert to Saved. You'd think this command is pretty easy to interpret. If you've really messed up something in your image, the best option is often simply to revert the entire file to the last saved version by selecting Revert from the File menu. In most applications, it's the same as closing the file without saving changes, then reopening it, but in Photoshop, Revert doesn't go back to the file that's saved on disk unless you actually selected Save from within Photoshop after opening the file. If you open an image in Photoshop, do a bunch of stuff, then choose Revert, what you get is the file as it first appeared in Photoshop. What's the difference?

The big difference is that anything you do using the Missing Profile or Profile Mismatch warnings doesn't get undone when you revert. For example, when you open an Untagged image, and use the Missing Profile warning to assign the Adobe RGB profile, if later you choose Revert you'll get an Adobe RGB image, not an Untagged one. What's worse is that when you make a conversion using the Profile Mismatch warning—actually changing the numbers in the file—choosing Revert will give you the image after the conversion, not the image that was saved on disk.

Worse still, when all you've done to the image is to change its profile or make a color conversion using the Profile Mismatch warning, the Revert command is dimmed and unavailable. We think this is a bug, and we hope it gets squashed, but keep an eye out for it—it's quite obscure. If you run into this situation, the only way to get back to the original image is to close it without saving, then re-open it (which is what we think Revert should do under all circumstances). If you do choose Revert, any changes you've made since the file was opened are lost, however, so proceed with caution. Note that the Revert feature is undoable.

The History Palette

There is a school of thought that dictates, "Don't give people what they want, give them what they need." The Photoshop engineering team appears to advocate this—they spend hours listening to and thinking about what people ask for, then they come back with a feature that goes far beyond what anyone had even thought to request. For example, people long asked Adobe for multiple Undos (the ability to sequentially undo steps that you've taken while editing a Photoshop image). The result is the History palette, which goes far beyond a simple Undo mechanism into a whole new paradigm of working in Photoshop.

The History palette, at its most basic, remembers what you've done to your file and lets you either retrace your steps or revert back to any earlier version of the image. Every time you do something to your image—paint a brush stroke, run a filter, make a selection, and so on—Photoshop saves this change as a state in the History palette (see Figure 2-32). At any time, you can revert the entire image to any previous state, or—using the History Brush tool or the Fill command, which we'll discuss in a moment—selectively paint back in time.

Figure 2-32 The History palette

There is, however, an itty-bitty problem with the History palette: it can take up a lot of RAM. Sorry, did we say "a lot"? We meant "vast, awe-inspiring, mind-boggling quantities" of memory, particularly since Photoshop 6's 100-state limit has been increased to 1000 in Photoshop 7. As we pointed out in Chapter 1, Building a Photoshop System, Photoshop can require as much as 10 to 20 times your file size in RAM—or more—to perform efficiently when it is saving history states (that's 200 to 400 MB of RAM for a 20 MB image). Performing simple tasks such as opening, rotating, sharpening, and saving may take significantly longer when the History feature is turned on.

The History palette has two sections: snapshots and states. Let's take a look at each of these and how you can use them.

Snapshots. Early versions of Photoshop let you save a single snapshot of your document, representing a moment in time for your image. The History palette lets you save any number of snapshots so that at any time you can go back to a specific state. There are two main differences between snapshots and states.

• Photoshop records almost everything you do to an image as a state. By default, snapshots are only recorded when you first open an image and when you click the New Snapshot button in the History palette.

• When the number of states recorded on the History palette exceeds the Maximum Remembered States value (set in the History Options dialog box), the oldest states start dropping off the list. Snapshots don't disappear until you close the document.

Stepping through states. As we mentioned above, Photoshop saves every brush stroke, every selection, every anything you do to your image as a state on the History palette (though the state only remains on the palette until you reach the maximum number of states or you close the document). There are three ways to move among states of your image.

• To revert your image back to a state, you can click on any state's tile in the History palette.

• You can move the active state marker to a state on the History palette.

• You can press Command-Z to step back to the last state (just as you've always been able to do). But you can also press Command-Option-Z to move backward one state at a time, and Command-Shift-Z to move forward one state at a time.

In general, when you move to an earlier state, Photoshop grays out every subsequent state on the History palette, indicating that if you do anything now these grayed-out states will be erased. This is like going back to a fork in the road and choosing the opposite path from what you took before. Photoshop offers another option: if you turn on the Allow Non-Linear History checkbox in the History Options dialog box, Photoshop doesn't gray out or remove subsequent states when you move back in time (though it still deletes old states when you hit the maximum number of states limit).

Non-Linear History is like returning to the fork in the road, taking the opposite path, but then having the option to return to any state from the first path. For example, you could run a Gaussian Blur on your image using three different amounts—returning the image to the pre-blurred state in the History palette each time—and then switch among these three states to decide which one you wanted to use.

The primary problem with Non-Linear History is that it may confuse you more than help you, especially when you're dealing with a number of different "forks in the road."

The History Brush. Returning to a previous state returns the entire image to that state. But Photoshop's History feature lets you selectively return portions of your image to a previous state, too, with the History Brush and the Fill command. Before painting with the History Brush, first select the source state in the History palette (click in the column to the left of the state from which you want to paint). For instance, let's say you sharpen a picture of a face with Unsharp Masking (see Chapter 9, Sharpening) and find that the lips have become oversharp. You can select the History Brush, set the source state to the presharpened state, and brush around the lips (though you'd probably want to reduce the opacity of the History Brush to 20 or 30 percent by pressing 2 or 3 first).

The History Brush tool (press Y) is very similar to the Eraser tool when the Erase to History checkbox is turned on in the Options bar, but the History Brush lets you paint with modes, such as Multiply and Screen.

Fill with History. One last nifty technique that can rescue you from a catastrophic "oops" is the Fill command on the Edit menu (press Shift-Delete). This lets you fill any selection (or the entire image, if nothing is selected) with the pixels from the current source state on the History palette. We usually use this in preference to the History Brush or Eraser tools when the area to be reverted is easily selectable. Sometimes when we paint with those tools, we overlook some pixels (it's hard to use a brush to paint every pixel in an area at 100 percent). This is never a problem when you use the Fill command. However, Fill isn't available on high-bit images.

You've always been able to press Option-Delete to fill a selection or layer with the foreground color. In version 4, Photoshop added the ability to automatically preserve transparency on the layer when you add the Shift key (slightly faster than having to turn on the Preserve Transparency checkbox in the Layers palette). Similarly, you can fill with the background color by pressing Command-Delete (add the Shift key to preserve transparency). To fill the layer or selection with the current history source state, press Command-Option-Delete. And, of course, you can add the Shift key to this to fill with Preserve Transparency turned on.

Easter Eggs

It's a tradition in Macintosh software to include Easter Eggs—those wacky little undocumented, nonutilitarian features that serve only to amuse the programmer and (they hope) the user. Note that if your friends think you have no sense of humor, you might want to skip this section; it might just annoy you.

There are (at least) three Easter Eggs in Photoshop—two hidden screens and one quote list.

Liquid Sky. A tradition even more venerable than Easter Eggs is code names. Almost all software has a code name that the developers use before the product is christened with a real shipping name. Photoshop 4 was code-named Big Electric Cat (it's an Adrian Belew reference, if you care). Photoshop 5 was code-named Strange Cargo. Photoshop 6 was called Venus in Furs. Photoshop 7 was called Liquid Sky. To see the original Liquid Sky splash screen, hold down the Command key while selecting About Photoshop from the Apple menu (Mac OS 9) or the Photoshop menu (Mac OS X). In Photoshop for Windows, press Control-Alt and select About Photoshop from the Help menu.

Quotes. If you watch either the standard About Photoshop screen or the Liquid Sky splash screen, you'll notice that the credits at the bottom of the screen start to scroll by, thanking everyone and their dog for participating in the development process. Don't get impatient—the last person on the list is someone special. (Actually, if you are the impatient type, try holding down the Option or Alt key once the credits start rolling; that speeds them up.) At any time before or during the rolling credits, try clicking once just above the first line of credits (like above the name Thomas Knoll or Mark Hamburg). If the screen disappears, you've clicked in the wrong place. If nothing happens, you've done it right. Now just wait until the scrolling credits are finished, and you'll be treated to some very funny quotations.

Merlin lives! Finally (at least, this is the last one we know about), there's a little hidden dialog box nestled away. When you hold down the Option key while selecting Palette Options from the popout menus in either the Paths, Layers, or Channels palettes, Merlin happily jumps out. If you're on a Mac, don't forget to try clicking on Merlin for that extra kick.

The World of Photoshop

If our publisher weren't screaming bloody murder to get this book to the printer, we'd still be writing tips. But instead of waiting until the next edition of the book, try finding them for yourself. The more you play with Photoshop, the more you'll be rewarded with treasures from the deep.