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 |
---|---|
CropBox | Page size that is visible in a viewer (fallback for the other boxes, minimally required) |
BleedBox | Page size plus bleed (cut space) |
TrimBox | Size of trimmed (cut) page, "final" page size |
MediaBox | Size of the physical medium (print sheet) |
ArtBox | Size of the page content (artwork); might be used for imposition purposes |
In PDF/X, if ArtBox is defined at all, it must not differ from TrimBox.
In ConTeXt
End of August 2015 ConTeXt got the necessary setup keys to define these boxes (minimal example by Hans):
\showframe \setuplayout [location=middle, width=middle, height=middle, cropoffset=auto, trimoffset=1bp, bleedoffset=2bp ] \starttext \definepapersize[TestA][width=100bp,height=200bp] \definepapersize[TestB][width=150bp,height=250bp] \setuppapersize[TestA][TestB] test \stoptext
The auto
option only works with layout=middle
(message otherwise).
The offset are accumulative (so crop < trim < bleed).
The default CropBox and TrimBox handling is unchanged, so one really needs to set this when it's needed. The already present interactionscreen cropping is unchanged.
ConTeXt doesn’t set ArtBox at the moment, since nobody seems to need it.