Xerox 721P87491 manual Image orientation mismatch B

POSTSCRIPT

Figure 2-9.Image orientation mismatch B

Printer’s paper

orientation

Slow

A

Output

without rotation

Output

Image

A

Slow

Rotated

A

Fast

Output with rotation

The scan order of an image relative to the content of the image is not important. It is important that the scan order of the image in the desired orientation is relative to the scan order of the page.

There are circumstances during which a transformation cannot be avoided by any ordering of image data (such as when the image sides are not parallel to the sides of the paper, or when the image is skewed), but for many cases, you can avoid a rotation by ensuring that the data in the image is in the correct order.

Ensuring optimum image data order is complicated by the fact that the rotations are not tied to the use of the rotate operator in a PostScript program, or to implied rotations in the image-to-user space transformation. The transformations in the figures above are automatically performed on data by DocuPrint NPS when required as part of rendering. The transformations specified in PostScript are part of a specification of the desired position of an image in terms of the default user coordinate system.

The following example shows the choice of row or column to describe an arbitrary one-dimensional slice of an image that depends on the viewpoint.

XEROX DOCUPRINT NPS GUIDE TO USING PAGE DESCRIPTION LANGUAGES 2-29