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An introduction to the EPS (Encapsulated PostScript) file format

Adobe's EPS (Encapsulated PostScript) file format is substantially different in nature from DaVinci's other supported file formats. The PostScript data format was originally designed to store information relating to the positioning and proportioning of image data for printers, not computer displays. PostScript-enabled printers interpret EPS data directly to produce high-quality output directly from PostScript files. While visual previewing of .PS files has been implemented in a few applications, the format was not originally designed for that purpose.

However, as interfaces became more powerful and more visually oriented, a means had to be found to allow previewing of PostScript data, and Encapsulated PostScript followed. EPS files normally include a small, low-resolution TIFF image, or alternately a Windows metafile, which is used as a graphical representation of the data as it will appear on a printed page. Since metafiles are proportionately more exact than bitmaps, vector-based metafiles can generally produce a "truer" representation of the EPS data onscreen than bitmapped TIFFs, provided the application displaying the metafile properly accounts for page dimensions.

When importing EPS files, DaVinci uses a Windows metafile (.WMF) to display the PostScript data onscreen, but it does not directly interpret all the EPS data in the file. Metafile preview images in EPS files will thus not have the quality of the actual EPS data printed on a "true PostScript" printer, since "true PostScript" printers ignore the preview image completely and take their instructions only from the EPS data.

If your application converts a metafile image into a DIB, PostScript data will be lost and the resulting printout will likely appear "blocky".

If an imported EPS file doesn’t contain a preview image, DaVinci will display a black rectangle with the file name of the imported file. It will not try to generate its own preview. The printing on a PostScript printer is yet possible in full quality.

Not every PostScript-enabled printer can print every EPS file. PostScript interpreters are available for most popular printers to emulate "true PostScript", but DaVinci can not check the useability of the transferred PostScript data on any given printer, nor can it gauge its output quality.

A free software package called GhostScript has been developed by the GNU Project to transform PostScript data into relatively high-quality bitmapped images. This software is available, both compiled and with source code, for several platforms including Windows from http://www.gnu.org


Þ c't 12/93 S. 240 Thomas Merz "The Encapsulated PostScript Graphics Format"

Þ c't 07/88 S. 205 Klaus Zerbe Kartei "Postscript - die Seiten-Beschreibungssprache von Adobe"

Þ http://www.muc.de/~tm

Þ Microsoft System Journal Sept/Oct 5/1993 S. 112 Thomas W. Lipp Graphic Conversion under Windows: The Encapsulated PostScript Format