Bleed & crop marks
When artwork extends all the way to the edge of the printed page, it is common to use a “bleed”. This means extending the ink past the crop mark. By doing this you ensure that minor errors in registration or trimming don’t produce an unsightly white line along the edge of the artwork. All artwork must have 3mm bleed if you require the image to bleed off the edge of the paper.
Page-layout programs, such as Adobe InDesign can easily handle “bleeds” and can automatically place crop marks. When setting up a new document in InDesign, you can add bleed in the New Document panel.
Producing a PDF with crop marks
Your optimum submission format is PDF. The easiest way to produce this file format is by exporting from InDesign. You can also add crop marks in this process. Crop marks indicate where a page will be cut (or trimmed) after printing. They should be 3mm long, 3mm outside of the page area and coloured in the colour ‘registration’ to ensure they appear on each colour separation.
To produce a PDF simply go the the File Menu in InDesign and select EXPORT.
In the PDF present menu select Press Quality. In the left hand column, select Marks and Bleeds and tick the Crop Marks box and make sure that the “Use Document Bleed Settings’ is selected.