Flattening DCS workflows
Transparency flattening depends on processing objects and colors before output. However, DCS files are typically preseparated, so in many cases the inks cannot be merged and then reseparated. This means transparency may not be compatible with some DCS workflows.
One DCS workflow is much easier in Adobe InDesign CS2: working with Photoshop DCS 1.0 and 2.0 files. Adobe InDesign CS2 can merge most Photoshop DCS 1.0 and 2.0 files during export or output. As a result, you can preview transparency for a Photoshop DCS 1.0 and 2.0 file.
For more information on requirements for merging Photoshop DCS files, see “Merging rasterbased Photoshop DCS and EPS files” on page 46.
When a DCS file is directly affected by transparency in an InDesign layout and it can’t be merged, use Photoshop to convert the file to PDF or native Photoshop (PSD) format before flattening the InDesign document. (Converting to an EPS file is not recommended because the conversion won’t preserve spot colors if any were used in the DCS file.)
Flattening OPI workflows
To accurately calculate transparency flattening at imagesetter resolution, high-resolution image data must be available when flattening occurs. Flattening occurs when exporting or printing, but before PostScript code is generated. Due to this processing order, care must be taken in OPI workflows to make sure high-resolution data is available at output time.
The easiest course of action is also the most reliable:
1 The customer imports high-resolution graphics into the layout, and keeps them with the document so that the high-resolution data is present whenever flattening and output occurs.
2 In the Advanced panel of the Print dialog box, Omit for OPI: EPS option is on, so that the document can function within an OPI workflow.
The presence of high-resolution data doesn’t have to slow down screen display; the Typical
Display and Optimized Display commands under the View menu can display the images using a lower on-screen resolution or replace them on-screen with gray placeholders. The settings used by these commands are user-customizable.
If there is a possibility that the high-resolution images may be replaced with low-resolution proxies with the exact same name (as a result of automatic relinking), use the Links palette to embed the high-resolution images in the file to ensure that they will be present at output time.
If the low-resolution proxy images containing OPI comments are still present when the document is sent to the RIP, the low-resolution data will be present at the flattening stage. This will result in low-resolution output where the low-resolution images are involved. To make highresolution data available to the flattener under this scenario, the customer should replace any images that are directly involved in transparency on the layout with high-resolution versions
before critical flattening and output. The customer doesn’t have to replace all images—just the ones involved with transparency. To save time, you can use the Affected Graphics option in the
Flattener Preview palette to quickly identify the images that need to be swapped out with their high-resolution versions.
A quick way to remember how to manage transparency and OPI is to remember the phrase
“fatten before you flatten,” with “fattening” defined as ensuring that high-resolution images have replaced all low-resolution images before output.
Understanding transparency flattener presets
InDesign CS2 comes with three transparency flattener presets built in. They are optimized for low, medium, and high-resolution output. The flattener controls in Adobe InDesign CS2 are now consistent with Adobe Illustrator CS2 and Adobe Acrobat 7 Professional. Adobe InDesign CS2 defaults to Medium Resolution for fast output on the customer’s desktop printer. In a print service provider workflow, the High Resolution flattener preset is recommended (or a similar preset customized for your workflow) because the results of this preset are most likely to be press quality. Low Resolution should be used only for rough proofing or online output.
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While the High Resolution flattener preset is recommended for prepress output, there is a chance that some jobs may encounter output problems if, for example, memory limits are reached or the output resolutions don’t match your workflow. To confirm which settings produce the best results on your equipment, run some test jobs containing transparency, starting with the High
Resolution transparency flattener preset. If you encounter quality or performance issues, you may need to create a customized transparency flattener preset for your shop, as described below.
You can use the Save and Load buttons in the Transparency Flattener Presets dialog box to save your tested presets and then load them on other computers in your shop or at a customer site.
It’s important to understand that the process of flattening transparency can result in either vector objects or rasterized areas, as a consequence of balancing reproduction quality against the speed of flattening. Of course, for service provider output, quality is the highest priority.
To create or edit a flattener preset:
1 Choose Edit > Transparency Flattener Presets.
2 Do one of the following:
• Click New to create a preset.
• To base a preset on a predefined preset, select one in the list, and click New.
• Select a custom preset in the list and click Edit.
Note: You can’t edit one of the default flattener presets, but you can select one as a starting point for a new preset that can be edited to match your workflow.
3 In the Flattener Settings dialog box, type a name in the Preset text box or accept the default name.
4 Drag the Raster/Vector Balance slider only if necessary. In most service provider workflows, there is little reason to use a value lower than 100. Lowering this value enables more rasterization of objects. You might lower this value for very complex pages that cause unacceptably long output times.
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Note: The rasterization that occurs depends on the complexity of the page and the types of overlapping objects. InDesign attempts to flatten objects only when necessary. Objects and spreads that aren’t affected by transparency aren’t flattened.
5 Do the following only if necessary:
• Set a Line Art and Text Resolution for artwork that’s rasterized as a result of interaction with transparency (except for gradient objects, which are covered by the next option). This option only takes effect when Raster/Vector Balance is below
100. In most cases, the value should not be changed. If you decide to change it, a good guideline is to start with the minimum acceptable resolution for line art on your output device and work up from there until output quality is as desired.
However, if your goal is quality, start with Raster/Vector Balance set at 100, in which case Line Art and Text Resolution no longer applies.
• Set a Gradient and Mesh Resolution for gradient objects. In general, specify the same resolution used for placed images (typically 300 dpi). InDesign will not necessarily rasterize all gradient objects; it will rasterize only where necessary due to interaction with transparency. InDesign may use this setting to rasterize gradients in placed graphics if the gradients interact with transparency and are saved in a file format that provides native transparency information to InDesign (such as
Illustrator 10).
Note: Do not change this value to improve feathered edges or drop shadows.
InDesign automatically increases the resolution for Feather Width or drop shadow
Blur Width values (in the Feather and Drop Shadow dialog boxes, respectively) that drop below 0.5 points.
6 Select any of the following, and then click OK:
• Select Convert All Text to Outlines to convert all text to outlines throughout the document. Whether or not you select this option depends on how text is used in the document in relation to transparency. If significant areas of text overlap transparent areas, some text may be converted to outlines while the rest of the text is not converted. InDesign attempts to flatten only where necessary. At resolutions below 1200 dpi, the text converted to outlines may appear slightly different than the nonconverted text. This is because the conversion slightly thickens text, and is most noticeable at small type sizes. Selecting this option converts all of the text to outlines, resulting in text that appears consistent.
• Select Convert Strokes to Outlines to convert all strokes in the document to outlines, not just the ones whose objects have transparency.
• Select Clip Complex Regions to decrease the probability of stitching, or jaggies, where rasterized areas meet areas that still remain in vector form. When the
Raster/Vector Balance value is less than 100, complex areas are sometimes rasterized during the flattening process. Typically, areas of the layout are rasterized in rectangular regions that can cut through objects. This can result in stitching.
Selecting Clip Complex Regions decreases the probability of stitching by ensuring that the raster/vector boundary falls along existing objects’ edges. If stitching occurs in PDF files exported from InDesign, turn off Smooth Images in Adobe
Acrobat (in the Smoothing panel in the Preferences dialog box). If the stitching disappears after changing the preferences, it’s only a screen display artifact and typically does not appear in printed output.
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