Printing grayscale to a laser printer

Original Article Date: Nov 4, 2002

To plot screens to a laser printer in MicroStation V7, the printer must have PostScript capability. Read along as our resident helps you modify a pentable.
Updated 2002-11-04 to include a suggestion for dealing with opaqueness.

To plot screens to a laser printer, the printer must have PostScript capability. Make a copy of the PSCRIPTC.PLT file as a backup. Open the PSCRIPTC.PLT configuration file with an ASCII text editor and add the following pen statements to control the screening (grayscaling).

*IMPORTANT* Make sure that the "change_pen=" statement in PSCRIPTC.PLT is set to "color" or "both". Add the following PEN lines are present anywhere after the "change_pen=" statement:

PEN(n)=(a-b)/RGB=(x,y,z)

Where "n" is the pen number
"a-b" is a single element color or a range of element colors
"x,y,z" are the Red Green Blue values

To control the degree of lightness of screen (grayscale), use these values after the "RGB=" statement inside the parentheses:

For Use
10% screen - (233,233,233)
20% screen - (204,204,204)
30% screen - (178,178,178)
40% screen - (153,153,153)
50% screen - (127,127,127)
60% screen - (102,102,102)
70% screen - (77,77,77)
80% screen - (26,26,26)
BLACK - (0,0,0)

The following is an example pen statement that will set color 0 to a 30% screen:

(The color "0" you see on the monitor will be 30% grayscale on the printout.)

PEN(1)=(0)/RGB=(178,178,178)

The following example will map colors 0 through 8 to black and colors 9 through 16 to a 40% screen:

PEN(1)=(0-8)/RGB=(0,0,0)
PEN(2)=(9-16)/RGB=(153,153,153)

Note: The Pen number to the left of the equal sign, in parentheses, should not be set lower than 1. Even though some printers/plotters have a pen 0 on their palette, MicroStation will not recognize this and reject their plot configuration file.

Save this file under a new name with the PLT extension. In MicroStation under File > Print/Plot > Setup > Drivers, choose your new file name. You can continue to plot normally.

2002-11-04(Update)

Brent James offers this tidbit of information: One scale of gray that I find most useful is 0%(white) using the following statement: pen(200)=(200)/RGB=(254,254,254). When placing an opaque shape with CO=200 between text elements and an aerial photo, this setting whitewashes the background under the text thus making it more readable.

AskInga Article #22