You can use the following methods to track down the reason for image distortion in exported PDF files.
- Not enough Virtual Memory has been applied for exporting layouts to PDF: In the PDF Preferences pane is a field for Virtual Memory allocation. This virtual memory space is used to page PostScript information to disk before it is passed off to the PDF processor (chosen by selecting either Direct to PDF or Create PostScript File for Later Distilling in the PDF Preferences pane). If this value is set too low for the size or complexity of the job you are exporting, QuarkXPress has to execute more frequent data exchanges to the virtual memory space and can theoretically run out of memory while attempting to process the job. This can cause Image information to be incompletely written within an exported PDF. The best practice for QuarkXPress is to set this value at the maximum allowed value of 1024.
- Images embedded within other images: While commonly encountered in certain PDF workflows, it is not a good practice to do what is called 'multiple embedding' of images. For example, if you place an EPS file into another Photoshop EPS, Import that second EPS into a QuarkXPress layout, export that layout to PDF, and then reimport the PDF into another QuarkXPress page and output that to a PDF, the embedded EPS images may not be properly output when exporting the layout to PDF. A good rule of thumb to follow is to use no more than one level of embedded images when constructing pages that are to be exported to PDF.
- Transparency layering relationships: If you have several objects to which you have applied transparency, including objects to which you have applied a drop shadow, the layering of these objects can affect how QuarkXPress flattens the transparent and drop shadow regions. This will in turn affect output of your images when exporting as PDF. To see if this is the issue with your layout, re-layer the objects to which you've applied transparency. It is likely that certain layering combinations will resolve the any image distortion issues. For in-depth information on working with Transparency and Drop Shadows in QuarkXPress, please see the QuarkXPress 8 White Paper 'Best Practices: Transparency.'
- Imported Photoshop PSD files imported into a QuarkXPress layout that is then exported to PDF can export with distorted pixel data. This often will display in the PDF as horizontal lines in the resulting PDF. To address this behavior, save the PSD file from Photoshop using a different image format, such as TIFF or EPS.
- DCS 2.0-formatted EPS files: DCS (Desktop Color Separation) files contain a low resolution composite file that references either external separation files (DCS 1.0) or internal separation files (DCS 2.0). When you export a DCS file to PDF, only the composite file is referenced for output, and the exported image will display in the PDF and print in low resolution. You should generally not use DCS files if you have a PDF workflow.
- Image or box damage: Any kind of corruption in an image or the box into which it is imported can cause image distortion. To test for this, create a new project and draw a box. Import the suspect image into it and export the layout as PDF. If you suspect the box itself is the culprit, delete the box, draw a new box, and import the image. If you suspect the project itself is causing the problem, it is possible that simply doing a Save As will correct any layout- or project-level problems.
More Information: Choosing a different output method can often resolve your PDF output problem. For example, if you normally use the Direct to PDF method of outputting PDF files, change your PDF Preferences to Create PostScript File for Later Distilling. For more information on the different methods to create a PDF, see Solution AE0255, 'How to Create PDF Files from QuarkXPress.'
Background: There are several reasons image information could become garbled in an exported PDF. These range from virtual memory usage issues to image file format type. Any combination of the variables listed below can contribute to failure of image output:
- Not enough Virtual Memory has been applied for exporting layouts to PDF.
- Images have been embedded within other images.
- Transparency layering relationship need to be changed in the layout.
- Some Photoshop PSD files can become distorted when using the Direct to PDF method.
- DCS 2.0-formatted EPS files have been imported into the layout you want to export as PDF.
- Image or box damage may be affecting the loading of image pixel data into the PDF.