Illustrator Layer Highlights

Illustrator Layer Highlights

Because it's designed to create complex vector artwork, Illustrator handles layers in some unique ways. You can create template layers for tracing images, toggle a layer between Outline and Preview modes, and set layer printing.

Creating Template Layers

Sometimes you may want to use a piece of bitmapped artwork as the basis for creating a vector drawing. For example, you've captured an image with a digital camera or scanned a photograph, but you want to render the bitmap as line art. One way of utilizing the bitmapped artwork is to use the Live Trace command in Illustrator CS2. (We describe this feature in "Special Vector Tools in Illustrator" in Chapter 5, "Getting to the Point of Vector Graphics.") But the more traditional way is to place a bitmapped file onto an Illustrator template layer and manually trace the image with the Pen tool. If you're good with the Pen tool, this method may still produce the best result.

To create a template layer, choose File > Place, and choose the image file you want to trace, placing it on the currently selected layer. Then double-click the layer in the Layers palette. In the Layer Options dialog box, check Template, and then click OK (Figure 12-15, left). By default, all images on this layer are dimmed to 50% opacity (which can be adjusted), and the layer is locked. Create a new layer and use the Pen tool to trace the outlines of the image (Figure 12-15, right). Note that the Template layer shows a special layer icon in the left column of the Layers palette.

Previewing and Outlining Layers

Just as Illustrator provides two modes of viewing entire artwork files Preview and Outline you can toggle the view status of individual layers, sublayers , and objects. Check the Preview check box in the Layer Options dialog box to toggle this status.

(For more on the value of switching between these views, see "Highlights of the Illustrator Interface" in Chapter 7, "Managing and Customizing the Interface.")

Printing and Not Printing Layers

Turning on and off the printing status of layers is useful when you're creating versioned files. At the time of printing, only layers with the Print status turned on will print. You can control the printing status of Illustrator artwork on a layer-by-layer basis. To make a layer nonprinting, uncheck the Print check box in the Layer Options dialog box.

Tip: Create Animations and Sequences

Illustrator allows distributing multiple objects each onto their own layer. This may be useful for creating Flash animations, for example. Highlight a group or layer in the Layers palette. To release each object to its own layer, choose Release To Layers (Sequence) from the palette menu. To release objects to layers and create a cumulative sequence, choose Release To Layers (Build) from the palette menu.

InDesign Layer Highlights

Unlike in Photoshop and Illustrator, most layouts in InDesign contain more than one page. InDesign layouts may also include master pages, guides, and text wraps, which give working with layers a different flavor.

Layers Include All Pages

Illustrator artwork normally consists of a single page. Layers created in Illustrator manage the objects on that one page. Layers in InDesign, however, apply to all pages of the publication. You can't create different sets of layers on different pages. You must keep this in mind as you're designing your publication, and you must create a layer arrangement that will work with all your pages.

Master Pages and Layers

Master pages in InDesign are used to create pages that contain common elements headers, footers, page numbers , and so on. Changing an object on a master page automatically changes the object on all the pages that are based on that master.

Master pages share the same layers just as document pages do. Objects on a particular layer of the master page appear behind objects assigned to the same layer on a document page. Understanding this stacking order that the document page is in front of the master page is important when positioning artwork. For example, you may need to place artwork on a document page in the same spot where a page number is located on the master page (Figure 12-16). To make a master-page object appear in front of a document page object, you must put it on a layer higher in the stacking order.

Guides, Text Wrap, and Layers

InDesign provides superior controls for working with guides and text wrap when you're working in a layered document.

Guides in InDesign are treated as objects, just like other "regular" page elements. They can be selected, moved, copied , and pasted. They can also be applied to different layers within your artwork. When selected like any other page object, guides show their layer selection color .

In addition, you can show and lock guides on a layer using controls in the InDesign Layer Options dialog box (see Figure 12-3, above). For example, in a file with language versions, each on its own layer, you can use this feature to hide guides selectively by turning off the visibility for guides for the other language layers.

In some cases, you may also want to control text wrapping on a layer-by-layer basis. If you are working with different language editions of a publication, for example, you may not want a text wrap from another language layer to affect the layout in the currently visible language. In that case, in the Layer Options dialog box, choose the option Suppress Text Wrap When Layer Is Hidden.

Transparency Flattening and Layers

Creating InDesign layers can also be useful when you're working with artwork that includes type and transparency objects in close proximity. Transparent objects must be flattened for printing, but often, you won't want to flatten type objects. Placing type on a higher plane in the stacking order can prevent production problems such as having some type outlines thicken (called "spreading") when adjacent to transparency objects. We describe how to use layers to eliminate unwanted spreading in "Best Practices for Handling Transparency" in Chapter 16, "Preflight and Printing."