When you prepare a document for print production, a number of marks are needed to help the print service provider align separation films for producing proofs, measure film for correct calibration and ink density, trim film to size, and so on. Printer marks indicate the boundaries of document boxes supported by Adobe PDF, such as trim boxes and bleed boxes.
You can add printer marks temporarily at print time using the Marks And Bleeds panel of the Advanced Print Setup dialog box, or you can embed printer marks in the file (and optionally in a layer) using the Add Printer Marks dialog box. For information about adding printer marks to just the printed output, see Include marks and bleeds.
A PDF created from Adobe InDesign CS and later can include printer marks, either in a separate layer or on the page. You can view these marks using the Layers tab in Acrobat. If the printer marks were exported as a layer, any printer marks you create using the Acrobat Add Printer Marks feature replace the InDesign printer marks. If the printer marks are not in a layer, Acrobat printer marks overlay InDesign printer marks and might not align.
Use the Set Page Boxes dialog box (formerly called Crop Pages) to define boundaries for trim, bleed, and art when preparing your PDF for printing and other output. You can adjust the margins of document boxes supported by Adobe PDF, including the media (page size), trim, bleed, and art boxes. This capability is useful if the printer marks you add using the Add Printer Marks tool (not the Marks And Bleeds panel of the Advanced Print Setup dialog box) would be clipped because the crop box is too small to accommodate the marks. Print service providers can also use this tool to expand the page size for imposition tasks.
You can switch between boxes without losing the margins you set for each. As you adjust individual boxes, the preview in the Set Page Boxes dialog box is redrawn to reflect the new settings. For example, if you expand the crop or media box, the page content “shrinks” in the preview.
When the crop box is expanded, the media box adjusts accordingly.
Very thin lines, called hairlines, are problematic in offset printing. If left as is in PDFs, they might not appear in the final printed piece. The Fix Hairlines tool can find most hairlines and replace them with a heavier-weight line.