A combination of new and expanded Preview features let you quickly see potential print problems in an Adobe PDF file, saving time, reducing costs, and resulting in fewer late-stage errors.
45 ADOBE ACROBAT 6.0 Inspecting and Fine-Tuning the PDF Document
Previewing transparency flattening in Acrobat
The Transparency Flattener Preview palette allows you to detect objects in a PDF document that are transparent, and objects that will be affected by transparency flattening. Transparent content is highlighted in red. (For information on why transparency must be flattened, see “About transparency flattening” on page 11.) While Acrobat 6.0 Profes- sional shares flattener preview capabilities with Illustrator CS and InDesign CS, it does not include the option to create custom presets.
Use the Transparency Flattener Preview palette to determine which areas will be affected by transparency. You may also want to consult with your service provider to ensure that you’ve selected the proper flattening settings. To preview transparency flattening:
1 Choose Advanced > Transparency Flattener Preview.
The Flattener Preview palette lets you see the interactions of specified transparent areas and adjust the options for output.
2 Click Refresh to populate the text boxes with the current transparency flattening settings.
3 Select preview settings.
4 To magnify the preview, click in the preview area. To pan the preview, press the spacebar and drag.
5 Drag the Rasters/Vectors slider or enter a value to specify the degree of rasterization in complex areas of the artwork.
6 Specify a rasterization resolution for rasterizing complex areas.
7 Select additional flattening settings. (See “Transparency flattener options” on page 61)
8 Click Refresh to show the new settings.
Note: To actually flatten a PDF file for output in Acrobat, click Advanced in the Print dialog box, select Transparency
Previewing how colors will overprint
Overprint Preview mode provides an on-screen simulation that approximates how blending and overprinting will appear in color-separated output. Overprinting effects can also be simulated when you output to a composite printing device. Both of these methods are useful for proofing documents that will be color-separated. If you are previewing spot colors that have been converted to process colors, consider the following:
• Adobe applications offer many interfaces for converting spot colors to process colors, including the InDesign Ink Manager, InDesign Print dialog box, Illustrator Swatches palette, and the Acrobat Advanced Print dialog box. When converting spot colors to their process-color equivalents, it is imperative to understand the impact on overprinting behavior. In some cases, converting a spot color to a process color will cause overprinting to “disappear,” or cause the appearance of the overprint to be lost.
• PostScript and PDF overprinting rules state that individual channels in CMYK colors cannot overprint unless their value is Zero. This is known as “nonzero overprinting.” For example, if a spot color conversion resulted in CMYK equivalents of 5% Cyan, 5% Yellow, 100% Magenta, and 10% black, any overprinting objects using this color will no longer overprint after the spot color is converted to process.
• Conversely, if a spot-to-process conversion resulted in CMYK values that were 0% Cyan, 10% Yellow, 100% Magenta, and 10% black, the Cyan channel will overprint, but none of the other colorants will overprint.
• This type of nonzero overprinting conversion can result in a change in appearance of the final output. It is important to simulate all spot color to process color conversions using Acrobat 6.0 professional to accurately predict the result of the conversions.
Appearance of artwork on monitor (left) and printed artwork (right)
To preview how colors will overprint and blend:
With the PDF file open, choose Advanced > Overprint Preview to turn the overprint display on and off. When overprint previewing is on, a checkmark appears next to the Overprint Preview command.
Previewing color separations
Separation Preview lets you easily preview the process and spot color separations in an Adobe PDF document. You can turn the color plates for the current page on or off in any combination, quickly preview the effect of changing spot colors to process color equivalents, and view spot and process ink coverage percentages in a specific area by simply placing the cursor over that area. When you turn off colors in a color separations preview, the results are shown in the main window.
When viewing multiple colors, the separations are shown as their respective colors; when viewing them individually, the separations appear in grayscale. Displaying color separations does not change the file itself or the output, only the separation preview.
To preview color separations:
47 ADOBE ACROBAT 6.0 Inspecting and Fine-Tuning the PDF Document
2 Choose Advanced > Separation Preview.
3 Do any of the following:
• Move the mouse around on the page to view the ink values that Acrobat will use for the separations at any given point on the page. These ink values are based on the current working space and proof setup profiles.
• To display a separation, select the color name. Or, to display all process colors at once, select CMYK (Windows) or CMYK Plates (Mac OS).
• To omit a separation, deselect the color name.
4 To convert a spot color to process, select the color until the process color icon appears. This conversion is for previewing only; it does not affect output.
Color Separation Preview with cyan and black turned off