Achieving Reliable Print Output from Adobe ... - Adobe Partners

Chapter 2: Flattening basics
Flattening transparency accurately reproduces—by using opaque objects—the visual effect of
transparency on printed output or in exported file formats that don’t support live transparency.
The Transparency Flattener (Flattener) in Adobe publishing applications is the mechanism that
is responsible for performing the conversion. You control the way the Flattener does its work by
configuring its settings based on the output requirements of the job.
Types of transparency
Transparency in Adobe publishing applications is referred to as either live or flattened. As a general
rule, files that contain live transparency are more desirable due to their device independence
and ease with which they can be edited.
Live transparency
The transparency attributes of objects created in Adobe publishing applications stay live and
fully editable while in their native applications; and the transparency attributes remain live
in applications that support the native file formats. They are considered live because they can
interact with other objects that are placed beneath them, allowing those objects to show through
the transparency. With the exception of Photoshop, the use of live transparency in a file gives it
a very high degree of device independence because the transparent elements are maintained as
vector art rather than raster images with a fixed resolution.
The following file formats may contain live transparency:
• Adobe Illustrator 9, 10, and CS (.AI)
• Adobe InDesign 2 and CS
• Adobe Photoshop 6, 7, and CS (.PSD)
• Adobe PDF 1.4 and 1.5 (Acrobat 5 and 6)
• Version 6 TIFF (TIFF files saved from Photoshop 6 or later)
Flattened transparency
Flattened transparency is generated when you convert a file that contains live transparency into
a format that doesn’t support live transparency. Objects that have been flattened do not contain
any transparent elements—the Flattener recreates the transparency effect by using opaque
objects.
The following common file types do not support live transparency (the Flattener must flatten
transparent objects prior to printing or exporting): PostScript, EPS, DCS, PDF 1.3 (Acrobat 4)
and earlier, GIF, JPEG, BMP, and versions of TIFF that do not conform to the TIFF 6.0 specification
(for example, TIFF files created with a version of Photoshop software prior to version 6.0).
Determining if an object will be flattened
This guide focuses on objects and placed files to which you have directly applied transparency, as
well as objects and placed files that interact with them. An object that has a transparency effect
applied to it is called a source of transparency. An object or placed file that appears under a source
of transparency (regardless of the layer it’s on) interacts with transparency. Objects that are a
source of transparency or interact with transparency are processed by the transparency flattening
process, possibly resulting in changes in their composition in the output.
PDF versions and transparency
When saving a file as PDF in Adobe CS applications,
PDF 1.3 is listed as Acrobat 4; PDF 1.4 is listed as
Acrobat 5; and PDF 1.5 is listed as Acrobat 6.
Because PostScript does not support live transparency,
any PDF produced by Acrobat Distiller®—even
though it may be PDF 1.4 or 1.5—will not contain
live transparency. All transparency is flattened in the
process of PostScript generation.
Editable transparency in Illustrator files
An EPS or PDF file that was created in Adobe
Illustrator 9, 10, or CS may have been saved with
the Preserve Illustrator Editing Capabilities option
selected (in the EPS or Adobe PDF Format Options
dialog box). In the case of EPS and PDF 1.3, the file
will contain flattened transparency; however, you can
access the native Illustrator data by opening the file
in an appropriate version of Adobe Illustrator. At this
point, you can edit the live transparency and resave it
with appropriate flattener settings.
Source of transparency
An object that has a transparency effect applied to it
is called a source of transparency.
Interacts with transparency
An object or placed file that appears under a source of
transparency (regardless of the layer it’s on) interacts
with transparency.
An object is a source of transparency if any of the following applies:
• It has an opacity of less than 100% applied to it.
• It has any blending mode other than Normal applied to it.
• It has a drop shadow or feather applied to it.
• It has a inner glow or outer glow effect applied to it (Illustrator).
• It has an opacity mask applied to it (Illustrator).
• Its fill or stroke has a style, brush, pattern, or filter effect that itself has any of the previous
properties.
Achieving reliable print output from Adobe
applications when using transparency
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