Flattening Transparency

Flattening Transparency

You may find that all those cool effects that you put into your illustration don’t print correctly. When you print a file that has effects such as drop shadows, cool gradient blends, and feathering, Illustrator turns transparent areas that overlap other objects into pixels and leaves what it can as vectors — this process is called flattening.

So what actually is flattening? Look at Figure to see the difference between the original artwork (on the left) and the flattened artwork (on the right).

Click To expand
Figure: Artwork before and after flattening is applied.

Notice that in Figure, when the artwork was flattened, some of the areas turned into pixels. But at what resolution? This is why you want to know about flattening, so that you can determine the quality of art yourself — before getting an unpleasant surprise at the outcome.

Flattening a file

If you have taken advantage of transparency or effects using transparency (which we discuss in Chapter 26 of this minibook), follow these steps to get the highest quality artwork from your file:

  1. Make sure that you’ve created the artwork in the CMYK mode.

    You can change the document’s color mode by choosing File®Document Color Mode.

  2. Choose Effects®Document Raster Effects Settings.

    The Document Raster Effects Settings dialog box appears, as shown in Figure.

    Click To expand
    Figure: Choosing the quality of your rasterized artwork.

  3. Choose the resolution that you want to use by selecting an option in the Resolution area.

    As a default, the rasterization setting is the Low (72 ppi) option, which is fine for the screen. Select the Medium (150 ppi) option for printers and copiers, and select the High (300 ppi) option for press.

  4. Choose whether you want a white or transparent background.

    If you select the Transparent option, you create an alpha channel. The alpha channel is retained if the artwork is exported into Photoshop.

  5. You can generally leave the items in the Options section deselected:

    • The Anti-Alias check box applies anti-aliasing to reduce the appearance of jagged edges in the rasterized image. Deselect this option to maintain the crispness of fine lines and small text.

    • The Create Clipping Mask check box creates a mask that makes the background of the rasterized image appear transparent. You don’t need to create a clipping mask if you select the Transparent option for your background.

    • The Add Around Object text field adds the specified number of pixels around the rasterized image.

  6. Click OK.

    The next step is to set the transparency options in the Document Setup dialog box.

  7. Choose File®Document Setup; click the flyout menu button in the upper-right corner of the Document Setup dialog box and select Transparency.

    The Export and Clipboard Transparency Flattener Settings dialog box appears. From the Preset drop-down list, select the Low, Medium, High, or Custom option. Select the Low option for on-screen viewing, the Medium option for printers and copiers, or the High option for press. Choose the Custom option if you want to control more of the settings yourself.

    Click OK.


If you find yourself customizing the settings on a regular basis, choose Edit®Transparency Flattener Presets to create and store your own presets.

You can apply the flattening in several ways. Here are three simple methods.

  • Select the object(s) that require flattening and choose Object®Flatten Transparency. Choose one of the default settings or a custom preset that you created from the Settings drop-down list and click OK.

  • Choose File®Print and select Advanced from the list of print options on the left. Choose a preset from the Overprint and Transparency Flattener options. If you used the Attributes palettes to create overprints (for trapping used in high-end printing), make sure that you preserve the overprints.


    Overprints will not be preserved in areas that use transparency.

  • Choose File®Save As and choose Illustrator EPS. In the Transparency section of the EPS Options dialog box, choose a flattening setting from the Preset drop-down list.

Using the Flattener Preview palette

Want to preview your flattening? Use the Flattener Preview palette by choosing Window®Flattener Preview. The Flattener Preview palette does not apply the flattening, but it gives you a preview based upon your settings. Click the Refresh button and choose to show options from the flyout menu (see Figure). Test various settings without actually flattening the file. Experiment with different settings, and then save your presets by selecting Save Transparency Preset from the flyout menu. The saved settings can be accessed in the Preset drop-down list in the Options dialog boxes that appear when you save a file as an EPS or in the Document Setup dialog box.

Click To expand
Figure: The Flattener Preview palette.

Click the Refresh button after making changes to update the preview.


Zoom in on the artwork by clicking in the preview pane. Scroll the artwork in the preview pane by holding down the spacebar and dragging. Zoom out by Alt+clicking (Windows) or Option+clicking (Mac).

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