Transparency works across Adobe applications, and you need to be aware of a variety of settings and preparation steps before printing documents containing transparency.Editor's Note: You can view the first article on Acrobat layers
here. This article also uses a PDF file, which you can
download here.
Adobe applications offer the ability to modify objects in ways that can affect the underlying artwork, creating the appearance of transparency. This can be accomplished by using the Transparency palette's opacity slider in applications such as InDesign, Illustrator, or Photoshop, or by changing the blending mode in a layer or with an object selected.
Transparency works across Adobe applications, and you need to be aware of a variety of settings and preparation steps before printing documents containing transparency.
Previewing transparency
When printing, objects with transparency are broken down, so any overlapping objects are converted into either separate vector shapes or rasterized pixels (see Note, below, for more on raster images). This retains the look of the transparency. This process of converting transparent objects into vectors and pixels
is referred to as flattening. Flattening essentially eliminates the transparency while maintaining its appearance.
Before flattening occurs, you can determine how much of the transparent area remains vector, and how much becomes rasterized. Some effects, such as drop shadows, must be rasterized in order to print correctly.
Note: Rasterization is the process of changing vector objects, including fonts, into bitmap images for the purpose of displaying and printing. The amount of ppi (pixels per inch) is referred to as the resolution. The higher the resolution in a raster image, the better the quality. When flattening occurs, some objects may need to be rasterized, depending upon flattening settings.
If you received a PDF file but did not create the file, you may not know if, or where, transparency has been applied. Acrobat's transparency preview shows you where transparency is used in a document. This feature can also help you to determine the best flattener settings to use when printing the document.
Next Page: Using the transparency controls.
Now that you know how transparency works, let's take a look at the transparency controls.
1. Open the file you downloaded. If necessary, click the Next Page button to navigate to page 2. If the entire page is not visible, press Ctrl+0 (Windows) or Command+0 (Mac OS) to fit the entire page in
your window.
2. Choose Tools > Print Production > Transparency Flattening. The Flattener Preview window opens.
3. In the Preview Settings section, click the Refresh button. The Refresh button scans the content of the current PDF to identify if transparency features have been used. In this document, it recognizes transparency and outlined strokes. The Flattener Preview now shows a preview of the newsletter on the right side of the window. Keep this window open.
Setting flattener preview settings
1. In the Flattener Preview window, choose Transparent Objects from the Highlight dropdown menu. The photo image and three of the musical notes are highlighted in red, indicating that they have transparent properties.
2. In the Flattener Preview window, use the Flattener Settings to choose how much of the artwork you wish to retain as vector artwork and how much you want to rasterize. Click and drag the Raster/Vector Balance slider to the farthest position to the right. This maximizes the amount of artwork to remain as vectors.
Note: The preview disappears as you select new settings. It becomes visible again after you click the Refresh button.
The settings vary from complete rasterization, which is obtained by dragging the slider completely to the left, to maximum retention of vectors, obtained by dragging the slider completely to the right.
3. From the Line Art and Text drop-down menu, choose 300 pixels per inch.
4. Click the Refresh button and a new preview appears. Position your cursor over the image of the musical notes in the lower right corner of the window, and click to increase magnification.
Use the zoom capabilities to better identify smaller objects that are affected by transparency. If necessary, hold down the space bar, then click and drag, to scroll within the preview area.
5. To zoom out, click the Refresh button to see the entire page.
6. In the Flattener Settings portion of the window, click and drag the slider entirely to the left. This causes Acrobat to preview which objects will be rasterized if this setting is used when printing.
7. Click the Refresh button, then choose All Affected Objects from the Highlight dropdown menu. Note that a significantly larger portion of the page is now covered in red. If a lower raster setting is used, the majority of the document will be rasterized—or converted to a bitmap.
Note: Documents that contain many transparent objects may take longer to print when higher Flattener settings are used, which rasterizes fewer page elements.
8. If you want to use the selected transparency flattener settings when printing, click the Apply button. When you are finished previewing how the various transparency flattening settings affect different portions of your document, click the close button in the upper corner of the window to close the Flattener Preview window.
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