Working with Clipping Paths


Some graphics file formats ‚ including TIFF, JPEG, and Photoshop EPS, and Photoshop-native (.psd) files ‚ let you embed a clipping path in the file. A clipping path is used to mask certain parts of a picture and reveal other parts . For example, if you want to create a silhouette around a single person in a crowd of people, you could open the file in an image editing program like Photoshop, and then create and save a clipping path that isolates the shape of the person. (You could also erase everything except the person you want to silhouette; not only can this be time-consuming , but if you want to reveal other parts of the picture later, you're out of luck.)

If you want to use a clipping path to mask parts of a picture, InDesign offers three options. You can

  • Use a graphics file's built-in clipping path. (Be sure to check the Import Options in the Place dialog box when you import the image and check the Apply Photoshop Clipping Path option as described in Chapter 23.)

  • Create a free-form shape that will act as your mask in InDesign and then place a picture in the shape.

  • Create a clipping path in InDesign by choosing Object Clipping Path or pressing Option+Shift+ z +K or Ctrl+Alt+Shift+K.

Regardless of the method you use to clip an imported picture, you can modify a clipping path by moving, adding, deleting, and changing the direction of anchor points and by moving direction lines.

Cross-Reference ‚  

See Chapter 25 for more information about modifying free-form shapes . See Deke McClelland's Photoshop 7 Bible (Wiley Publishing) for more on creating clipping paths in Photoshop.

Creating clipping paths in Photoshop

Creating a clipping path in Photoshop is simple, once you get the hang of the process. A path is essentially a selection, which you can create with any of the Photoshop selection tools, including tracing your own selection to hand-draw a path. Once the selection has been made, here's how you make a path:

  1. Open the Paths pane by choosing Window Paths.

  2. Using the pane's palette menu, choose Make Work Path.

    You'll be asked to choose a Tolerance setting in pixels ‚ the smaller the number, the finer the path's shape.

  3. Click OK to accept your setting.

    A work path will now display in the Paths pane, showing in white the area contained by the path.

  4. Convert the work path into a named path by double-clicking the work path in the pane or by choosing Save Path in the palette menu.

  5. Give the path a name , then click OK.

  6. Now choose Clipping Path from the palette menu.

    You'll be asked to choose which path to use as a clipping path (you can have multiple clipping paths in a Photoshop file) and then be asked to choose a Flatness setting. Like the earlier Tolerance setting, the smaller the number of pixels, the finer the path's contours .

  7. Click OK.

That's it! The tricky part is creating the selection area to begin with.

 

Using a free-form shape to clip a picture

If you want to mask a portion of a picture that doesn't include a built-in clipping path, no problem. The easiest way is to simply edit the text-wrap boundary. To do so, set the text wrap to Wrap around Object Shape, then select the picture with the Direct Selection tool. The text-wrap boundary will appear as a blue line ‚ you can make it easier to select by setting offsets in the Text Wrap pane, which will move the boundary away from the frame edge, as Figure 25-6 shows. Now use InDesign's free-form editing tools, as covered in Chapter 27, to edit the text-wrap boundary.


Figure 25-6: To create a custom wrap, just edit the text-wrap boundary after selecting Wrap around Object as if it were any other path. The boundary is the blue path that appears outside the frame; you can more easily see and work with the wrap boundary if you enter offset amounts in the Text Wrap pane.

There are two other methods you can use as well:

  • You can use the Pen tool to create the shape, and then use the Place command (File Place, or z +D or Ctrl+D) to place a picture in the shape.

  • You can import the picture into a rectangular frame (by using the Place command with no object selected), use the Pen tool to create a free-form shape that surrounds the portion of the image you want to show, and then copy and paste the picture into the free-form shape. In this case, you must use the Paste Into command (Edit Paste Into, or Option+ z +V or Ctrl+Alt+V) to place the copied picture in the selected free-form shape. When you create the free-form shape, make sure that the default color for the Pen tool is set to None so that the shape you create is transparent. Otherwise, the colored area in the shape will obscure the picture behind it.

You're more likely to use the second method than the first because it's difficult to mask a portion of a picture without seeing it. Figure 25-5 shows a picture in a rectangular frame next to a copy of the same picture in a free-form shape.

Tip ‚  

The Pen tool lets you create one shape at a time. The Compound Paths command lets you combine multiple shapes to create more complex objects. For example, you could place a small circle on top of a larger circle and then use the Compound Paths command to create a doughnut-shaped object. Figure 25-9, later in this chapter, shows a picture in a compound path. (See Chapter 27 for more information about creating complex shapes with the Compound Paths command.)

Using InDesign's Clipping Path command

If you import a picture that doesn't have a clipping path, you can use the Clipping Path command (Object Clipping Path, or Option+Shift+ z +K or Ctrl+Alt+Shift+K) to generate one automatically in InDesign. The clipping paths that InDesign generates are based on a picture's value. For this reason, the Clipping Path command works very well for images that have a white background but no clipping path. It's less useful for pictures whose backgrounds have not been erased and for pictures that contain a broad range of intermingling values.

Tip ‚  

If you use the Clipping Path command to generate a clipping path for a picture that has a built-in clipping path, the one that InDesign generates replaces the built-in path.

To create a clipping path using the Clipping Path command:

  1. Select either the Selection tool or the Direct Selection tool, and then click on the picture to which you want to add a clipping path.

    If the Type tool isn't selected, you can press V to select the Selection tool or press A to select the Direct Selection tool.

  2. Choose Object Clipping Path, or press to display the Clipping Path dialog box, shown in Figure 25-7.


    Figure 25-7: The Clipping Path dialog box.

  3. To have InDesign detect the likely boundary of the image, as opposed to a white or other light background, choose Detect Edges from the Type pop-up menu.

    You can use the other options to select Alpha Channel or Photoshop Path as the clipping path, for pictures that have one or more of these ‚ InDesign can only use one as the clipping path.

  4. Enter a value in the Threshold field or drag the field's slider to specify the value below which pixels will be placed outside the clipping path shape (that is, pixels that will become transparent).

    Pixels darker than the Threshold value remain visible and thus are inside the clipping path shape. The lowest possible Threshold value (0) makes only white pixels transparent. As the value gets higher, less of the picture remains visible. The lightest areas are removed first, then midtones, and so on. (Click Preview to see the results of your changes without closing the dialog box.)

  5. The value you enter in the Tolerance field determines how closely InDesign looks at variations in adjacent pixels when building a clipping path.

    Higher values produce a simpler, smoother path than lower values. Lower values create a more complicated, more exact path with more anchor points.

  6. If you want to enlarge or reduce the size of the clipping path produced by the Threshold and Tolerance values, enter a value in the Inset Frame field.

    Negative values enlarge the path; positive values shrink it. (The Inset Frame value is also applied to the path's bounding box.)

  7. Click Invert to switch the transparent and visible areas of the clipping path produced by the Threshold and Tolerance values.

  8. If you want to include light areas in the perimeter shape InDesign generates based on the Threshold and Tolerance values, click Include Inside Edges.

    For example, if you have a picture of a doughnut and you want to make the hole transparent (as well as the area around the outside of the doughnut), click Include Inside Edges. If you don't click Include Inside Edges, InDesign builds a single shape (in the case of a doughnut, just the outside circle). The portion of the picture in the shape remains visible; the rest of the picture becomes transparent.

  9. Click Restrict to Frame if you want InDesign to generate a clipping path from just the portion of the picture visible in the picture frame, as opposed to the entire picture (such as if you cropped the picture).

  10. Click Use High Resolution Image if you want InDesign to use the high-resolution information in the original file instead of using the low-resolution proxy image.

    Even though using the high-resolution image takes longer, the resulting clipping path is more precise than it would be if you didn't check Use High Resolution Image.

  11. When you've finished specifying clipping path settings, click OK to close the dialog box and apply the settings to the selected picture.

Figure 25-8 shows a picture before and after a clipping path was applied to it using the Clipping Path command.


Figure 25-8: At left is a picture of coastal France with a picture of a glider superimposed. At right is the same set of pictures, but with a clipping path applied to the glider so the outside area is masked out, making it transparent.

You can remove a clipping path by choosing None as the Type in the Clipping Path dialog box. You can also select a different path ‚ detectable edges, alpha channel, embedded Photoshop path, or hand-edited path ‚ than was selected previously if you decide to change the current clipping path.




Adobe InDesign CS Bible
Adobe InDesign CS3 Bible
ISBN: 0470119381
EAN: 2147483647
Year: 2003
Pages: 344
Authors: Galen Gruman

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