SECTION 10.10
963
Prepress Support
include areas close to the edges of the medium that cannot be marked because
of physical limitations of the output device. Content falling outside this bound-
ary can safely be discarded without affecting the meaning of the PDF file.
•
The
crop box
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 of physical page geometry or intended
use; it merely imposes clipping on the page contents. However, in the absence
of additional information (such as imposition instructions specified in a JDF or
PJTF job ticket), the crop box determines how the page’s contents are to be po-
sitioned on the output medium. The default value is the page’s media box.
•
The
bleed box (PDF 1.3)
defines the region to which the contents of the page
should be clipped when output in a production environment. This may include
any extra bleed area needed to accommodate the physical limitations of cut-
ting, folding, and trimming equipment. The actual printed page may include
printing marks that fall outside the bleed box. The default value is the page’s
crop box.
•
The
trim box (PDF 1.3)
defines the intended dimensions of the finished page
after trimming. It may be smaller than the media box to allow for production-
related content, such as printing instructions, cut marks, or color bars. The
default value is the page’s crop box.
•
The
art box (PDF 1.3)
defines the extent of the page’s meaningful content
(including potential white space) as intended by the page’s creator. The default
value is the page’s crop box.
These boundaries are specified by the
MediaBox
,
CropBox
,
BleedBox
,
TrimBox
,
and
ArtBox
entries, respectively, in the page object dictionary (see Table 3.27 on
crop, bleed, trim, and art boxes should not ordinarily extend beyond the boun-
daries of the media box. If they do, they are effectively reduced to their intersec-
tion with the media box. Figure 10.3 illustrates the relationships among these
boundaries. (The crop box is not shown in the figure because it has no defined re-
lationship with any of the other boundaries.)