Scott Olswold

Screen Prints From QWS3270 (a terminal emulation application) Are Hard To Read

Blog Post created by Scott Olswold on Sep 28, 2016


  • Print jobs are hard to read.
  • The text on the paper is a very light gray/grey.
  • Screen prints from terminal emulation program/application are useless.



  • QWS3270
  • Terminal Emulation software
  • "Universal" print driver
  • Pharos Uniprint
  • Pharos Blueprint
  • Secured or Direct queues



The QWS3270 application, as other terminal emulation software does, ignores the background color when printing a screen from the mainframe application. By default, the application prints in Color, so in the process of printing the job, QWS3270 queries the print driver to determine if the printer supports color. Further, QWS3270 ignores the background when printing, sending only the text information.

While GREEN TEXT ON A BLACK BACKGROUND is nice on the screen, that green color doesn't translate well to grayscale, if the printer the job is delivered to is a monochrome laser printer (remember, back in the 60s, 70s, and 80s, most of this output was to green-bar paper on tractor-feed impact printers, so anything came out black; not so on a printer that is capable of 256 shades of gray). Let's consider our green, which in the monitor's color space is defined as R=0, G=255, B=0:

First, most printers' internal software simply converts color to gray using a rough average, where the 3 components are added together and then divided by three: (R+G+B) / 3. There's also a "luminosity" method that provides more weight to "green" because that's the color channel to which we're most sensitive; that formula is  0.21 R + 0.72 G + 0.07 B). The individual colors are first converted to a percentage: 0/100/0 and then added, so (0+100+0) / 3 = 33.3% (repeating 3). This is an example of text colored at 33.3%. It is difficult to read, even on screen. Imagine, quite sadly, what WHITE TEXT ON A BLACK BACKGROUND would look like in grayscale:                                 .



Within the QWS3270 application, start the session with the mainframe host and then go to Options > Session > Printing. Within the Printing dialog box, choose the "Black and White" option and click the "OK" button to set the selection. Now when QWS3270 prints, it ignores the driver function entirely and just sends text specified as "black."


NOTE: This is not a default setting for this and future sessions. It is only going to apply for the current session. If you desire a more permanent solution, a queue specific for theQWS3270 application must be provided to the workstation utilizing a printer driver that does not include color printing support, or, alternately, has been configured so as to appear to not support color printing.