Adobe CS5 Illustrator Transparency Flattening - dummies

By Jennifer Smith, Christopher Smith, Fred Gerantabee

If your Adobe Creative Suite 5 (Adobe CS5) Illustrator artwork has many effects it may not print correctly. When you print a file that has effects, such as drop shadows, cool gradient blends, and feathering, Illustrator flattens them, by turning into pixels any transparent areas that overlap other objects and leaving what it can as vectors.

To understand flattening, the Figure below demonstrates the difference between the original artwork (on the left) and the flattened artwork (on the right). Notice that in the flattened artwork some areas turned into pixels. But at what resolution? Flattening helps you determine the quality of the flattened art.

Artwork before and after flattening is applied.
Artwork before and after flattening is applied.

If you’ve taken advantage of transparency, or effects using transparency, follow these steps to produce the highest-quality artwork in your file:

  1. Make sure that the artwork you created is in 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.

    Choosing the quality of rasterized artwork.
    Choosing the quality of rasterized artwork.
  3. Choose the resolution you want to use by selecting an option in the Resolution area.

    Select the Screen (72 ppi) option for Web graphics, Medium (150 ppi) for desktop printers and copiers, and High (300 ppi) for graphics to be printed on a press.

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

    If you select the Transparent option, you create an alpha channel that’s 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 antialiasing 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.

    • The Preserve Spot Colors check box keeps any spot colors you have defined intact. Leave this checked.

  6. Click OK.

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

  7. Choose File→Document Setup.

    From the Transparency section in the middle of the dialog box, click the Preset drop-down list and select the Low, Medium, High, or Custom option. Select the Low option for onscreen viewing, the Medium option for printers and copiers, or the High option for press quality. To control more settings, click the Custom button to the right of the drop-down list.

  8. Click OK.

If you customize settings regularly, 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 objects that require flattening and choose Object→Flatten Transparency. Choose a default setting or a custom preset (that you created) from the Preset 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 panel to create overprints (for trapping used in high-end printing), make sure to preserve the overprints.

    Overprints aren’t 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. If your transparency options are grayed out, your file has no transparency.