bw-imp — convert a black and white bw image file to imPRESS bitmap


bw-imp [-D ] [-s squaresize] [-w width] [-n height] [-t thresh] [-X page_xoff] [-Y page_yoff] [file]


bw-imp converts an 8-bit monochrome bw(5) format file (read from the standard input if not specified) to Imagen imPRESS language codes for plotting a gray-scale image on a 300dpi Imagen laser printer.

The gray level is plotted on the Imagen as a small pattern of dots, by default using "ordered dither", magnifying each input pixel into multiple output pixels. The -D option causes the gray levels to instead be plotted using halftones, as in newspaper/magazine reproductions of photographs. The -t option turns off the dithering, and uses the supplied integer value as a threshold value. Input pixels with magnitude >= thresh are output as white, otherwise they are output as black. Each input pixel produces exactly one output pixel. If the input file is already bi-level, such as might be produced by the halftone(1) program, then this is the option to be used.

Printing is done in portrait mode. The largest image which can generally be printed on an 8.5 by 11 inch piece of paper is 2240 by 3200 pixels, and the default page offsets are calculated for this size. For smaller images, such as 512 squared, -X750 and -Y1200 produce the image roughly centered on the page.


bw-imp will take several CPU-minutes (on a VAX 780) to convert a single file.


The following invocations are fairly typical:

pix-bw  -ntsc  image.pix  |  bw-imp  |   qpr  -qi300  &

rle-pix  image.rle  |  pix-bw  -ntsc  |  bw-imp  |  qpr  -qi300  &

The X and Y options in the bw-imp command below are to approximately center a 1024x1024 or 512x512 figure on a 8.5 by 11 inch sheet of paper. As of release 4.0 the default margins on an output page resulting from a bw-imp usage are smaller. This allows a larger image to be printed on one page.

rle-pix  image.rle  |  pix-bw  -ntsc  |  bw-imp -X 200 -Y 800  |  ipr -L impress -q i300

To threshold and invert the black/white sense of a pix file, use:

bwmod  -m  -8  -a  255  image.pix  |  pix-bw  |  bw-imp  -t1  | ttcp  -t  -p35  printhost

To use the halftone package:

pix-bw  -ntsc  image.pix  |  halftone  |  bw-imp  |   qpr  -qi300 &


rle-pix(1), pix-bw(1), bw(5), pix(5)


Error messages are intended to be self-explanatory.




This software is Copyright (c) 1989-2016 by the United States Government as represented by U.S. Army Research Laboratory.


Reports of bugs or problems should be submitted via electronic mail to <>.