SAMS Teach Yourself Adobe® Photoshop® CS2 in 24 Hours [Electronic resources] نسخه متنی

Creating Paths

There are three paths you can take when creating paths (sorry, I couldn't resist):

Create a path directly from a selection you've already made.
Create a path from scratch by using the Pen tools and drawing the path by hand.
Create a path using the Shape tools.

Paths via Selections

Depending on the image at hand, simply making a selection and converting it to a path can be the easiest and quickest way to create a path.

Let's look at an example. Figure 13.1 shows the test image, a tire gauge. We'll select the object, and make what's called a

clipping path, clipping it out of the background. Without Photoshop, you would achieve the same effect with a photographic print and a pair of scissors.

Figure 13.1. The test image. The goal is a clipping path that outlines the gauge.

As you remember, selection can be accomplished by using a number of tools. For this image, I selected the background with the Magic Wand and then cleaned up the selection using the Quick Mask. Other objects might be selected more easily by using a combination of the Elliptical Marquee and the Polygonal Lasso. You might even need to combine the results of several selection tools to get it all. Just keep the Shift key pressed to merge the selections. Figure 13.2 shows the selection.

Figure 13.2. The tire gauge is now selected.

Try it Yourself

Convert a Selection to a Path

Now that you have a selection, follow these steps to convert it to a path:

Make sure that the Paths palette is visible. If not, choose WindowPaths.

Choose Make Work Path from the pop-up menu on the Paths palette (see Figure 13.3).

Figure 13.3. The pop-up menu of the Paths palette.

The only option to set in the Make Work Path dialog box is Tolerance (see Figure 13.4).

Tolerance refers to how closely Photoshop follows the outline of your selection in creating the path. The smaller the tolerance, the more exact the path is.

Figure 13.4. The Make Work Path dialog box.

It's a Long and Winding Path

Be aware that complex paths can be resource intensive. More complexity means more points, angles, curves, and so on. The result can mean slower processing of the image, bigger files, and possible problems when printing.

For this image, I first tried a Tolerance of 5 pixels. As Figure 13.5 shows, the results were unacceptable. Photoshop was too flexible and approximate in creating the path at this setting. You can see that the smoother line of the path doesn't follow the outline of the stem closely enough.

Figure 13.5. When the path doesn't match the selection to your satisfaction, the Tolerance is set too high.

When this happens, I simply reach for my favorite Photoshop command: Undo. Undo the path conversion and try a lower Tolerance setting. After some experimentation, I found that a value of 1 pixel worked quite well (see Figure 13.6).

Figure 13.6. When Tolerance is set correctly, the path matches the selection satisfactorily.

Note how the path also appears in the Paths palette in Figure 13.7. Photo shop has named it

Work Path . You can rename the path by simply double-clicking it in the Paths palette. In the Save Path dialog box that appears, simply type the new pathname and click OK, as shown in Figure 13.7.

Figure 13.7. Rename paths by using the Save Path dialog box.

Choose Clipping Path from the Paths palette pop-up menu, and specify the path you just created as the clipping path.

Although renaming the work path isn't required, it's a good idea, especially if you might need the path again. If the path is left as a work path and you start a second path, one of two things will happen. First, if the work path is still active in the Paths palette, the new path will be added to it as a subpath. Second, if the original work path is no longer active in the Paths palette, the new path will replace it. (Undo and the History palette give you opportunities to recover the original path, but it's easier to simply rename it and transform it into a regular path at the time of creation.)

Another Path to Travel

There's also another way to create a path from a selection. Make a selection and then simply click the Make Work Path button at the bottom of the Paths palette. Photoshop automatically creates the path by using the same Tolerance setting you used for your last conversion.

Paths via the Pen Tools

Sometimes, making a selection is too difficult or requires too much work on a particular image. In that case, consider using the Pen tools and drawing the path by hand.

If you've used vector-based illustration programs, such as Adobe Illustrator or Macromedia FreeHand, you already know about Bézier-based drawing tools such as Photoshop's Pen tools. If you haven't used these kinds of tools before, you should know right up front that it takes a little practice, but the payoff is worth the effort. In addition to the standard Pen tools that draw a line and add or remove points on the line, Photoshop provides two additional Pen tools. The Freeform Pen tool gives you the power to draw any kind of line you wantstraight, curved, or squigglyand turn it into a path. And, when used with the Magnetic option, the Freeform Pen tool makes drawing around a complicated object much easier.

Bézier curve is defined by three points: one on the curve and two outside the curve at the ends of handles that you can use to change the angle and direction of the curve. If this sounds like gibberish, don't worry; you'll see some examples.

Try it Yourself

Using the Pen Tool

The best way to learn how to use the Pen tool is simply to play around with it in a new Photoshop document.

First, create a new Photoshop document big enough to move around in. Photoshop's default size (7x5 inches) sounds good, and a plain white background looks good.

Select the Pen tool. (It looks like an old-fashioned fountain pen nib.) Also make sure that the Paths palette is visible.

In the Options Bar, click the Paths button. It's the middle one in the first cluster of three.

Click somewhere near the left edge of the page. This is where your path begins. (Notice that Photoshop immediately creates a path called

work path in the Paths palette. This path can be renamed later in the same way described in the previous "Try it Yourself.")

To draw a straight line, simply move your cursor and click somewhere else. (Don't hold the mouse button down!) You've just created a

corner point, which means that Photoshop connects the two points with a straight line (see Figure 13.8).

Figure 13.8. Just two simple clicks create a corner point and a straight line.

To continue the path (but now with a curved line), move your cursor to the middle bottom of the window and then click and drag left. You'll see a curve immediately appear and change as you drag it (see Figure 13.9). You've just created a

smooth point, which means that Photoshop creates a smooth curve where two curved line segments meet.

Figure 13.9. A click-and-drag action creates a smooth point and a curved line.

To make this clearer, draw another smooth curve. Move your cursor to a point that is up and to the right of the second point; click and drag to the right and a bit down. Again a smooth point and a curve are created (see Figure 13.10).

Figure 13.10. Click and drag to create another smooth point on the same path.

Notice the point you created in step 5. It creates a nice smooth curve between the point you just created and the point you created in step 4. That's what a smooth point is all about.

As you have no doubt noticed, creating smooth points also results in the appearance of two

handles for each point. These handles can be used to change the angle and direction of a curve after you've initially established it. You'll learn more about them in the "Editing Paths" section, later in this hour.

Switch to another tool or click your starting point to end the path.

Okay, those are the basic ideas: straight lines via corner points and curved lines via smooth points. But there's more that you have to know about each one to use them effectively.

Corner Points

Corner points are easy. No matter what kind of line is coming into a corner point, the result is always an angle, not a curve. If a curved line comes into a corner point, it's the smooth point at the other end of that line that affects the line's angle (see Figure 13.11).

Figure 13.11. Corner points surround smooth points.

Restraining Order

If you want to constrain corner points so that they appear only at 45- or 90-degree angles, hold down the Shift key while you click to create the point.

Smooth Points

As you saw in the first Pen tool example, the behavior of smooth points is a bit more complicated and takes some getting used to. A smooth point always tries to create as smooth a curve as it can between two meeting lines (see Figure 13.12).

Figure 13.12. Smooth points do their utmost to create curves out of any situation.

Try it Yourself

Creating a Sharp Curve

There is a less smooth kind of curve you can create when you need it. It's called a

sharp curve. It looks like a pair of arches, or the top half of a heart, or a stick seagull, and the following steps show you how to create one:

In a new Photoshop document, begin a path with an initial point.

Create a smooth point as you normally would, by dragging after you click to set the point, making one curve.

Move the pointer so that it's exactly over the smooth point you just created. Hold down Option (Mac) or Alt (Windows) while you click and drag the mouse in the direction of the intended bump in the new curve. Release the key and the mouse button. Your screen should now look something like what you see in Figure 13.13.

Figure 13.13. Creating a sharp curve. The rightmost line is what I just created by using the Option or Alt key. It becomes a handle for the first curve.

Move the cursor to where you want the line to end; then click and drag in the opposite direction that you dragged in step 3. The line will draw itself from where you ended the first arch to where you just clicked at its end point. As you drag, the line will expand upward. Figure 13.14 shows the resulting sharp curve. If you didn't get it right where you wanted, you can use the handles to reshape it.

Figure 13.14. The final sharp curve.

Previewing the Path

When you're creating all these points and lines, there's a preview feature that can be very helpful. Look at the Tool Options bar. There's an option called Rubber Band, which you can access by selecting the Pen and clicking the down-pointing arrow next to the strip of tool icons. Activating this feature enables you to preview both straight lines and curves before you click to create them. Experiment to see this feature at work. Take a look at the other options, too. Each tool and shape on the strip has different settings accessible via this arrow.

Completing the Path

To complete a path, you have two choices:

close the path by connecting the final point to the initial point, or leave the path

open.

closed path means you have created a loop, so the final path has no beginning or end. To close a path, use the following steps:

Create a path by using whatever points you need.

After the last point, move your cursor so that it appears on top of your initial point. You'll see a small circle next to the Pen pointer.

Click to create a final corner point, or click and drag to create a final curve (see Figure 13.15).

Figure 13.15. The start and stop point is the gray one.

open path means the path has a beginning and an end. Figures 13.8 through 13.14 have all been open paths. To end a path that you want to keep open, use the following steps:

Create a path by using whatever points you need.

After the last point, simply click the Pen tool icon in the toolbar. The path now has an end.

The next time you click in the image, you'll be starting a new path instead of continuing your previous path.

Paths Are Composed of Subpaths

Saying that you've created a "path" is a little misleading. The line between each pair of points on a path is a path segment or subpath. Together, they make a path. You can manipulate the points and subpaths to change the shape of the path. One point to remember is that any path you create is not really part of the image. It's not a line drawn on the page. Until you add color to it, it's merely a theoretical line. That is, you aren't changing the actual image. When you stroke a path, it becomes a visible line. If you fill a path, it becomes a shape.