PDF/A in a Nutshell
The book about the new standard PDF/A by PDF/A Competence Center
PDFs often have to be reviewed both for overall appearance as well as for correct content. PDF content may look different in different PDF programs. Exporting a PDF to an image PDF where each page is simply an image will guarantee correct and consistent rendering of the PDF in any PDF viewing program – in exactly the same way the PDF will be printed on a modern output system.
To open the Switchboard, click on the menu item "Switchboard" under the "View" menu or use the keyboard short cut "Ctrl-2" or "Cmd-2". Then click on the "Document" group icon.
Click on the "Image export" icon to go to the image export action.
1. Select the output format for the image export. Besides exporting to individual TIFF, JPEG or PNG files, pdfToolbox 4.5 now also supports export of the source PDF into the destination PDF with the same number of pages as contained in the source PDF.
2. The recommended color space for producing a content softproof PDF is RGB. This ensures correct display even in PDF programs that do not support CMYK well.
3. For most purposes, an image resolution of 150ppi is a good compromise between amount of detail and file size. The images in the exported PDF will be compressed using lossless ZIP compression. If smaller file size is important, the PDF can afterwards be recompressed using JPEG - a JPEG compression level of "maximum quality" often decreases the file size by over 50% without sacrificing too much quality.
4. Always leave "Simulate overprinting" checked as otherwise the exported PDF may not look exactly the same as it would when output on print from the source PDF.
5. Click on execute to initiate the image export.
After having clicked on the "Execute" button, choose the location and name for the exported PDF. Make sure not to overwrite your source PDF.
Depending on the number of pages in the source document, the export may take a while. Typically it should take about 1 second per page.
After completing the export, please double check the size of the exported PDF. If the file size is more than you find acceptable, use the "Recompress" action in the "Images" group of the Switchboard, and apply JPEG compression. Choose between maximum quality for least lossy compression, or high quality if small file sizes are very important. Lower quality values will begin to introduce visible artifacts.
As an example, the rendering of the sample PDF in Mac OS X Preview is shown here:
1. Original PDF file: The grayscale photo is rendered incorrectly (inverted/negative) and clearly differs from the correct rendering as it actually would be printed.
2. Exported image PDF: Because all page content now is an RGB image, more or less any PDF program will be able to display the page correctly.