Pages may be prepared either for a finished medium, such as a sheet of paper, or as part of a prepress process in which the content of pages is placed on an intermediate medium, such as film or an imposed reproduction plate. When an intermediate medium is part of the process, it becomes important to distinguish it from the finished page. Additional production-related content that falls outside the boundaries of the finished page (e.g. registration marks) may be needed on the intermediate product. To handle these requirements, a PDF page can define up to five separate boxes (boundaries) to control the various aspects of the imaging process:
Defines the bounds of the physical medium on which the page is to be printed and the location of the page (the contents) on that medium. A media box’s origin (left and bottom) is usually 0, 0, but it may be offset to adjust the alignment of the contents. Negative values will move the contents to the right and up; positive values will move the contents to the left and down.
When changing the size of a media box PDFClerk Pro can optionally
scale the contents of the page to adjust to its new size, either
proportionally, or independently for each axis. When scaling
proportionally PDFClerk Pro can align the contents on the page
automatically. See the entry on the
Display Boxes Inspector for
information on editing media boxes.
Defines the region to which the contents of the page are to be clipped (cropped) when displayed or printed. Unlike the other boxes, the crop box has no defined meaning in terms intended use; it merely imposes clipping on the medium’s contents.
Defines the region to which the contents of the page should be clipped during the finishing process, such as extra bleed area to accommodate the physical limitations of cutting, folding, and trimming equipment. The page as printed may include finishing marks that fall outside the bleed box, and are cut off when trimmed.
Defines the dimensions of the finished product after trimming. It may be smaller than the media box to allow for production-related content, such as trim and registration marks, color bars, etc.
Defines the extent of a page’s meaningful content (including potential white space) as intended by the page’s creator.
In PDFClerk Pro display boxes are defined in terms of insets from
the media box, similar to margins on a sheet of paper. To learn more
about editing display boxes and the effect of specific settings see
the entry on the
Display Boxes Inspector.