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Printing Shades of Grey In Postscript Mode
DocumentID: 634064
Revision Date: 29-Feb-96 3:03:32 PM

The information in this document applies to:
WordPerfect® 5.1 for DOS

Problem

Symptoms: I have a customer interested in learning whether or not we can get 256 shades of grey on a graphic image using the Apple LaserWriter printer. He's not so concerned with the display as with printing. I am a little confused on how many shades of grey we can expect to get on the printer. Solutions: Postscript is limited to 256 gray levels. The human eye cannot really perceive anything greater. The number of levels WordPerfect can output to a Postscript printer depends on the type of image:

1.      Gray scale. Postscript's halftoning feature is used for bitmaps that contain gray scale information. WP supports 1, 2, 4, or 8 bits per pixel for gray scale. One bit per pixel is essentially a black and white bit map with no real gray scaling. These images are usually generated with a scanner and imported into WP. Eight bits per pixel will give 256 shades of gray and the halftoning is done by Postscript, not WP.

2.      Black and white bit maps. This is the clop art stuff and each pixel is either on or off.

3.      Vector graphics images. This is the kind of image DrawPerfect creates. The Postscript gray shades are limited to 64 different shades.

4.      EPS (Encapsulated Postscript). These are totally dependent on how the images were created. Depending on fancy things done by the EPS file, the 256 gray shade limit can be increased, but this is usually never the case.

Answer:

Details:


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