WORKING WITH PLACED GRAPHICS

Although Illustrator can open and edit Photoshop documentsas well as accept raster (and vector) objects copied from Photoshop or InDesign and pasted into Illustratorto work with a raster image as a single, flat object in an Illustrator document, you must place the file.

Placing Graphics

On the File menu is the Place command, which opens a dialog very similar to the one displayed with the File, Open command (see Figure 20.1). Instead of opening a file, however, the Place dialog inserts the external file on the current document's artboard. Placed files, even other Illustrator documents, are not directly editable when inserted via the Place command. In other words, constituent objects in the placed graphic cannot be manipulated independently of the whole.

Figure 20.1. The Place dialog.

In the Place dialog are three options:

• Link: Link to the original file (checked) or embed (unchecked) the graphic in the Illustrator document (see the "Linking and Embedding Placed Images" section, later in this chapter).

• Template: Check to insert the image and automatically set the image's layer to Template mode (see the section on the Layers palette in Chapter 15, "Understanding Illustrator Palettes and Menus").

• Replace: Active only if another image is selected in the document prior to using the Place command. Check to replace the selected image with the one currently chosen in the Place dialog.

Illustrator can place the following file formats into an active document; in the case of textual documents (text, Rich Text Format, and Microsoft Word), the text of the file is placed as editable type within a selected text object or as a new type area if no object is selected:

• Adobe Illustrator documents and templates (*.ai, *.ait, *.pdf)

• Adobe PDF files (*.pdf)

• AutoCAD Drawing and Interchange files (*.dwg and *.dxf)

• BMP (*.bmp, *.rle, *.dib)

• Computer Graphics Metafile (*.cgm)

• CorelDRAW versions 510 files (*.cdr)

• Encapsulated PostScript (*.eps, *.epsf, *.ps)

• Enhanced Metafile (*.emf)

• FreeHand versions 4, 5, 7, 8, and 9 files (*.fh*)

• GIF89A (*.gif)

• JPEG (*.jpg, *.jpe, *.jpeg)

• JPEG2000 (*.jpf, *.jpx, *.jp2, *.j2k, *.j2c, *.jpc)

• Macintosh PICT (*.pic, *.pct)

• Microsoft Word (*.doc)

• PCX (*.pcx)

• Photo CD (*.pcd)

• Photoshop (*.psd, *.pdd)

• Pixar (*.pxr)

• PNG (*.png)

• Rich Text Format (*.rtf)

• SVG (*.svg)

• SVG Compressed (*.svgz)

• Targa (*.tga, *.vda, *.icb, *.vst)

• Text (*.txt)

• TIFF (*.tif, *.tiff)

• Windows Metafile (*.wmf)

When placing some of these formats, an additional options dialog appears (see Figure 20.2). In some caseswith PDF and Illustrator files, for examplethe dialog asks where to crop the artwork or, if the original is a multipage document, which page to place. In such cases, only one page may be placed at a time, although the same file may be placed multiple times, with each instance displaying a different page.

Figure 20.2. When placing a PDF or Illustrator file, the Place PDF dialog appears, with Crop To box and page navigation features.

In addition to the Place command, supported graphic and text file formats may be placed as linked assets into the Illustrator document by dragging and dropping one or multiple files from

• Adobe Bridge

• The Desktop

• An Explorer (Windows) or Finder (Macintosh) window

• iPhoto (Macintosh)

Using Photoshop Layer Comps

In Photoshop CS and CS2, layers are augmented by the addition of the Layer Comps feature. Layer comps are snapshots of the state of layers in a documentwhich image, vector, type, and adjustment layers are turned on or off, as well as certain layer transformations (see the section on layer comps in Chapter 6, "Working with Layers in Photoshop"). Saved in Photoshop documents, layer comps may be taken advantage of when such Photoshop documents are placed into Illustrator (or InDesign).

When placing a Photoshop document that includes layer comps, the Photoshop Import Options dialog appears after you finish with the Place dialog (see Figure 20.3).

Figure 20.3. The Photoshop Import Options dialog displaying a document with layer comps.

At the top of the Photoshop Import Options dialog is a pop-up menu of layer comps saved in the Photoshop document. Below that is a preview of the selected layer comp (the Show Preview option is unchecked by default), as well as any comments written into the layer comp in Photoshop. The When Updating Link pop-up menu includes two options: Keep Layer Visibility Overrides, which tells Illustrator to preserve the layer comp as chosen regardless of any layer and layer comp changes made in the original document in Photoshop, and Use Photoshop's Layer Visibility, which ignores the chosen layer comp settings and updates the asset in the Illustrator document if changes are made in Photoshop.

The options, which affect only how the Photoshop document is handled inside Illustrator and not the original asset in any way, include

• Convert Photoshop Layers to Objects: If available, convert layers in the Photoshop image to Illustrator-editable objects, layers, and sub-layers in the Illustrator document. This option also attempts to make text in the Photoshop document editable within Illustrator as text.

• Flatten Photoshop Layers to a Single Image: If available, does not add Photoshop layers or objects to the Layers palette, but instead it creates a single, solid image like other raster image formats placed into Illustrator.

• Import Hidden Layers: Available if Convert Photoshop Layers to Objects is chosen. Import layers even if they were deactivated or hidden in Photoshop.

• Import Image Maps: Available if Convert Photoshop Layers to Objects is chosen. If the Photoshop document contains image maps created in Photoshop or ImageReady, they are preserved.

• Import Slices: Available if Convert Photoshop Layers to Objects is chosen. If the Photoshop document contains slices created in Photoshop or ImageReady, they are preserved and may be manipulated with Illustrator's Slice tool and Slice commands.

Try this exercise:

1.	Begin a new Illustrator document.
2.	Choose File, Place.
3.	In the Place dialog, navigate to the Photoshop sample files. On Windows that would be C:\Program Files\Adobe\Adobe Photoshop CS2\Samples. On the Mac that location would be Applications/Adobe Photoshop CS2/Samples.
4.	Place the Layer Comps.psd sample file and check the Link option.
5.	In the Photoshop Import Options dialog, turn on Preview and select the 6 Purple Votives layer comp.
6.	Set the When Updating Link pop-up menu to Keep Layer Visibility Overrides and click OK.

The only way to change the active layer comp for a placed Photoshop document is to relink it:

1.	Select the Layer Comps.psd file with the Selection tool.
2.	With a linked image selected, the Control palette updates to reflect information relevant to that type of object. On the far left of the Control palette is a rather wide button with an arrow on it. Click this button to access a menu of linked file options.
3.	Choose Relink, which opens the Place dialog again. Reduce the number of external assets to manage by creating multiple, related images in Photoshop as a single document with layer comps. Then place multiple instances of the same file into Illustrator, choosing different layer comps each time.
4.	Choose the same file (Layer Comps.psd) and click the Place button.
5.	In the Photoshop Import Options dialog select a different layer comp and click OK.

The commands on the Control palette's (unofficially named) Linked File menu are also available on the Links palette menu, and some also appear as buttons on the Links palette (see "Linking and Embedding Placed Images," later in this chapter).

Linking and Embedding Placed Images

Placed images may be either linked or embedded, with advantages and drawbacks to both.

Linking merely stores a reference to the placed graphic in the Illustrator document, not the placed graphic itself. Changes made to the original graphic file outside of Illustrator prompt Illustrator to ask whether you want to update the placed reference. In this way, a common image asset like a logo or photograph used in multiple projects may be changed across all documents simultaneously. Another pro is that the asset's file size is not added to the Illustrator document.

One drawback to linking is that, when transporting the Illustrator document, all image assets must be transported as well (or the document cannot print with high quality) and editing is severely restricted. Additionally, many effects and filters (Drop Shadow, for example) may be applied only to embedded images; applying them to linked images has no visible effect.

Linked placed graphics appear on the artboard with an X through them (see Figure 20.4).

Figure 20.4. This placed graphic is linked, as denoted by the X across the picture.

Embedding stores the placed copy of the original image directly within the Illustrator document and disassociates it with the external file. Embedding has two major advantages: A greater range of filters and effects are available for application to the embedded graphic, and additional assets need not be located and transported when moving the Illustrator document. If an asset is embedded in the Illustrator document, changes to the original file do not affect the placed copy, and Illustrator is totally unaware of changes made to the original. Additionally, the entire original asset is embedded in the Illustrator document, increasing the latter's file size on disk accordingly.

The Links palette (choose Window, Links to display the palette) tracks and manages linked and embedded assets (see Figure 20.5). Each linked asset has an entry on the Links palette, and various icons appear beside the entry's name to communicate important information:

• Embedded Artwork: Indicates that the asset is embedded in the document.

• Modified Artwork: Indicates that the linked asset has been updated outside of Illustrator.

• Missing Artwork: Indicates that the linked asset has been moved or deleted, or that the Illustrator document is no longer in the same location relative to the location of the asset. Printing with missing artwork results in low resolution output of the asset.

• Transparency Interaction: Indicates that the linked asset has or is touching another object that has some form of transparency active.

Figure 20.5. The Links palette.

Embed images in one of three ways: by clicking the Embed button that appears on the Control palette when the image is selected, by unchecking the Link box in the Place dialog, or by selecting a linked asset entry on the Links palette and then Embed Image from the Links palette menu.

At the bottom of the Links palette are four buttons that become active depending on the highlighted asset in the Links palette:

• Relink: Open a dialog to link to a missing asset from a new location to replace an asset with another; to relink to the same image, change its optionsfor example, to choose a different layer comp for display in placed Photoshop PSD files that include layer comps.

• Go To Link: Navigate the document window to display the linked asset.

• Update Link: If a linked asset has been modified outside of Illustrator, this re-reads the original file, updating the reference on the artboard.

• Edit Original: Open the linked asset in its source applicationfor example, a linked PSD document opens in Photoshop. Upon saving the asset in the source application, Illustrator instantly updates it on the artboard without the need to click the Update Link button.

Working with Live Trace

New in Illustrator CS2 is Live Trace, an automated utility to vectorize or trace raster images into vector objects (see Figure 20.6).

Figure 20.6. Raster image before tracing (left) and the same image after Live Trace with different tracing presets. From left to right: Grayscale, Color 6, and Photo High Fidelity.

When a raster image is selected in the Illustrator document, the Control palette displays the Live Trace button. Clicking the Live Trace button instantly traces the image with the last used or default Live Trace options. The down-pointing black arrow beside the Live Trace button is the Tracing Presets and Options menu. On the menu are all the default and user-created tracing presets, as well as the last item, Tracing Options.

In the Tracing Options dialog, default and user-created presets appear in a menu at the top. Often, a preset provides exactly the right settings for a particular tracing. When it doesn't, the options in the Adjustments and Trace Settings sections provide precise tracing control (see Figure 20.7).

Figure 20.7. The Tracing Options dialog.

The Adjustments section contains various options that are enabled or disabled by the choice of Mode:

• Mode: Select the color mode of the desired tracing, either color, grayscale, or black and white.

• Threshold: (Black and White mode) Set the limit among the possible 256 levels of gray (including black at 0 and white at 255) to convert from black to white. Any pixel lighter than the threshold value is converted to white; all others are black.

• Palette: (Color or Grayscale mode) Determine the colors used for fills and/or stroke when tracing. To create a tracing in a particular color libraryfor example, in spot colorsopen the needed library from the Window, Swatch Libraries command before using Live Trace. After it is opened, the library appears in the list of palettes.

• Max Colors: Determine the maximum number of colors allowed in the resulting trace. More colors equals richer detail but more paths.

• Output to Swatches: Choose whether to create swatches from the colors Live Trace picks from the traced image and uses to paint the tracing paths.

• Blur: Blur the traced image prior to tracing to limit the effects of pixelation and raster image artifactsfor example, dirt, scratches, or noise in color areas.

• Resample: Resample or change the resolution of the raster image prior to tracing.

Also dependent on the Mode, the Trace Settings options control to the fidelity of the tracing result:

• Fills: Determine whether Live Trace should fill traced paths or leave them unfilled.

• Strokes: Determine whether Live Trace should draw strokes or leave paths unstroked.

• Max Stroke Weight: (Available only if Strokes is checked.) Define in pixels the maximum weight or thickness of strokes in traced paths.

• Min Stroke Length: (Available only if Strokes is checked.) Define the minimum length of a traced stroke. The higher the number, the fewer paths resulting from the trace but the lower detail.

• Path Fitting: Determine how close to the pixels in the raster image vector paths should be drawn. The lower the number, the more closely paths follow the pixel shapes in the image.

• Minimum Area: Determine the minimum area in pixels to be traced. For example: an area 1- by 1-pixel is ignored and not traced if the value of Minimum Area is higher than 1.

• Corner Angle: Determine the angle that corners in the raster image must be before requiring a corner anchor point instead of a smooth anchor point.

The View section controls whether and how the raster image and vector tracing results are displayed in the Live Trace object.

Also in the Tracing Options dialog, on the right side, are counts of the number of paths, anchors, colors, and areas of the tracing result; the pixels per inch of the raster image; and the Save Preset button, which creates new presets for the Preset menu from the current settings.

Try this:

1.	Place a raster graphic.
2.	From the Control palette, click on the Tracing Presets and Options menu (the black arrow beside the Live Trace button).
3.	Choose the Color 6 preset. Within seconds (if that long) the raster image is traced into six colors of vector objects, making it look much like a screen print on a t-shirt or soda can.
4.	From the Tracing Presets and Options menu select Photo High Fidelity. The image retraces with more realistic options.

As the name implies, Live Trace is a live effect. Tracing settings can be tweaked at any time. Unless and until the Live Trace object is expanded, the tracing is always tied to the raster image and the level of detail, colors, and fidelity may be altered in real time.

Although Live Trace is a marvelous tool capable of stellar results, it isn't perfect. For example, when tracing an image with a white or even transparent background, Live Trace draws the background as white-filled paths. If the desired result is to have the traced object placed atop other objects that show through the negative space, those extraneous background paths must be deleted.

Moreover, Live Trace is not always the last step in working with traced objects.

To answer both (and other) scenarios in which the paths resulting from a trace must be accessed directly, you must expand the Live Trace object. With a Live Trace object selected, the Control palette displays the Expand button. Clicking it converts the object into a grouped collection of paths. From there, ungroup using the Object, Ungroup command to access each of the individual paths Live Trace drew and work with them as with any other path object.

After a placed image has been converted to a Live Trace object, modify it with the Object, Live Trace submenu, which enables a return to the Tracing Options dialog, as well as the following:

• Release the Live Trace and convert the object back to a placed image.

• Expand to break the live aspect of the Live Trace and expand it into a separate raster image and the tracing result.

• Expand as Viewed, which has the same essential functionality as Expand, but does not restore any hidden aspect of the Live Trace object, such as the original image if it is not shown.

• Use various settings from the View section of Tracing Options and Convert to Live Paint, which converts the Live Trace paths to a Live Paint object (see the Live Paint section of Chapter 18, "Working with Objects in Illustrator").

Working with Clipping Masks

Illustrator does not have the capability of erasing parts of a raster image like Photoshop, nor does it need that capability. It has clipping masks. Clipping masks hide portions of images, text, paths, shapes, or groups without changing them.

To create a clipping mask, place or draw the artwork to mask. Using any of the shape or drawing tools, draw a closed path in the shape of, and on top of, the portion of the artwork to remain visible. Select both the artwork and the mask object, and choose Object, Clipping Mask, Make. The mask object disappears, clipping away all areas of the artwork falling outside it (see Figure 20.8).

Figure 20.8. Before masking (left) and after masking (right).

Try this:

1.	Choose File, Place.
2.	Select any image and check the Link option in the Place dialog.
3.	On top of the placed image, draw a closed path or shapefor example, an ellipse, using the Ellipse tool. This is the mask object.
4.	With the Selection tool, select the mask object and Shift-click to select the placed image.
5.	Choose Object, Clipping Mask, Make. Any fill or stroke the mask object had disappears, and the placed image is clipped to take its shape.

When an object or objects are contained within a clipping mask, any transformation made to the clipping mask object equally transforms the mask and the object(s) within. To transform just the contents without affecting the clipping mask, deselect the object, then select it with the Direct Selection tool.

To release a clipping mask, choose Object, Clipping Mask, Release. Both the artwork and the mask object are restored and separated, though the mask object returns as an unfilled, unstroked path.

Working with Opacity Masks

Clipping masks are all or nothingthe masked artwork either shows fully or not at all. When you want a semitransparent statea soft-edged vignette, for exampleuse opacity masks (see Figure 20.9).

Figure 20.9. Before opacity mask (left) and after (right). The mask object was a gradient-filled circle.

Create an opacity mask in the same way as a clipping mask, with existing artwork and a mask shape. The difference is in the fill. Whereas the fill is irrelevant to a clipping mask, it is the basis for

an opacity mask. Fill the mask object with shades of gray to define transparency; black is completely transparent, white completely opaque. Set the opacity percentage or blending mode for the final masked artwork on the mask object. Select both the mask and the artwork, and choose Make Opacity Mask from the Transparency palette menu. The thumbnail preview of the artwork is joined by, and linked to, an opacity thumbnail resembling the mask object (see Figure 20.10).

Figure 20.10. An opacity mask shows two thumbnails in the Transparency palette, the masked artwork and the mask object.

On the Transparency palette, the Clip option turns any areas of the artwork that appear outside the mask object to black (invisible). In other words, if a circle is used to mask a square, the corners of the

square not overlapped by the circle are rendered invisible by the Clip option. Disable the Clip option for special effects like creating a window through artwork.

The Invert Mask option flips the black and white points, making what was completely invisible opaque and vice versa.

Try this:

1.	Choose File, Place.
2.	Select any image and check the Link option in the Place dialog.
3.	On top of the placed image, draw a closed path or shapefor example, an ellipse, using the Ellipse tool. This is the mask object.
4.	Fill the circle with the black-to-white radial gradient swatch on the Swatches palette.
5.	With the Selection tool, select the mask object and Shift-click to select the placed image.
6.	On the Transparency palette menu, choose Make Opacity Mask. The image should clip to fit the circle, and it should seem to fade out from a solid center.

In addition to making opacity masks from the Transparency palette menu, you can also choose the following options:

• Release Opacity Mask: Restore the mask and masked artwork to separate, unmasked objects.

• Disable Opacity Mask: Turn off the opacity mask without releasing it.

• Unlink Opacity Mask: Keep the mask applied to the artwork, but allow independent transformation of both the mask and the masked artwork.