Input and compilation/PDF/PDF boxes

Basics

While PostScript (and EPS, that is) knows only one kind of page size, defined by the BoundingBox (or HiResBoundingBox), the size of PDF pages can have different meanings – e.g. the visible page, the printed page, the cropped printed page. Therefore the PDF standard defines a set of "boxes":

Name	Meaning
MediaBox	Size of the physical medium (print sheet); this is the page format.
CropBox	Page size that is visible in a viewer.
BleedBox	Page size plus bleed (cut space); defines the trimmed page plus the bleed.
TrimBox	Size of trimmed (cut) page, “final” page size; the net result document format.
ArtBox	Size of the page content (artwork); might be used for imposition purposes; typically, it can be used to specify any section of the page.

In PDF/X, if ArtBox is defined at all, it must not differ from TrimBox.

In ConTeXt

\setuppapersize[A5][A5,oversized]

\setuplayout
 [location=middle,
  cropoffset=0mm,% default
  trimoffset=-7.5mm,% negative offset from MediaBox to TrimBox
  bleedoffset=3mm,% bleed size
]
\setupinteractionscreen[width=max,height=max]

\starttext
\showlayout
\stoptext

• Unfortunately, the offsets are not independent: If you define a cropoffset , you must add its value to the negative trimoffset .
• It doesn’t work without \setupinteractionscreen .
• cropoffset=auto only works with location=middle (message otherwise).
• You can’t set ArtBox, since nobody seems to need it. ( \externalfigure understands size=art if you need to place a PDF image by its ArtBox.)
• \setupbackend is not significant for the box calculations.
• \setupbleeding affects only image placement, but not the BleedBox, see the Template:manual manual.
• MediaBox (i.e. the size of the sheet) is taken from the second parameter of \setuppapersize .
• trimoffset specifies the difference between the CropBox and the TrimBox. This parameter seems to be completely ignored, if it is positive.
• bleedoffset defines the difference between the TrimBox and the BleedBox. Negative values yield a BleedBox that’s smaller than the TrimBox, which is against the specs. Values bigger than the (positive) trimoffset also make no sense.

Complete Example

This uses a print mode:

\setuppapersize[A5][A5,oversized] % oversized adds 15mm, enough for the crop marks

\setuplayout[
  location=middle,
  marking=on,
]

\startmode[print]
\setuplayout[
  cropoffset=0mm,% default
  bleedoffset=3mm,% bleed
  trimoffset=-7.5mm,% half of negative size difference of sheet and paper
]
\stopmode

\startnotmode[print]
\setuplayout[
  cropoffset=7.5mm,% shrink the visible page to the final paper size
  bleedoffset=3mm,
  trimoffset=0mm,% the TrimBox is influenced by the CropBox
]
\stopnotmode

\setupinteractionscreen[width=max,height=max]% activate!

\starttext
\showlayout
\stoptext