loki@NAZGUL.PHYSICS.MCGILL.CA (Loki Jorgenson) (05/16/91)
Has anyone any experience with the Tektronix Phaser PX? We
are observing rather ugly dithering side-effects (Moire patterns, donuts,
halftoning etc.) and wondering if it might not be possible to adjust
the angle/density values generated by the tocps facility to get better
results. We do it all the time for our B&W LaserWriter II NT. However,
I can't guess what values would be the most effective on a color
printer.
Thanks,
_ _ _ _
Loki Jorgenson / / _ _ _ _ _ \ \ node: loki@Physics.McGill.CA
Grad/Systems Manager /_/_/_/_/ \_\_\_\_\ BITNET: PY29@MCGILLA
Physics, McGill University \ \ \_\_\_/_/_/ / / fax: (514) 398-3733
Montreal Quebec CANADA \_\_ _/_/ phone: (514) 398-7027
-* Anatomically correct *-davidh8@pogo.WV.TEK.COM (David Haight) (05/17/91)
In article <9105152156.AA16481@nazgul.physics.mcgill.ca> loki@NAZGUL.PHYSICS.MCGILL.CA (Loki Jorgenson) writes: > > Has anyone any experience with the Tektronix Phaser PX? We >are observing rather ugly dithering side-effects (Moire patterns, donuts, >halftoning etc.) and wondering if it might not be possible to adjust >the angle/density values generated by the tocps facility to get better >results. We do it all the time for our B&W LaserWriter II NT. However, >I can't guess what values would be the most effective on a color >printer. > >Thanks, > > _ _ _ _ >Loki Jorgenson / / _ _ _ _ _ \ \ node: loki@Physics.McGill.CA >Grad/Systems Manager /_/_/_/_/ \_\_\_\_\ BITNET: PY29@MCGILLA >Physics, McGill University \ \ \_\_\_/_/_/ / / fax: (514) 398-3733 >Montreal Quebec CANADA \_\_ _/_/ phone: (514) 398-7027 > > -* Anatomically correct *- The following, down loaded to the printer, will solve the problem. The problem is not with the printer, but with applications that use screen angles that are not optimal for the Phaser PX. ----------------------------------------------------------------------- David Haight | davidh8@pogo.wv.tek.com | INTERNET Tektronix, GPID Div. | {backbone}!tektronix!pogo!davidh8| UUCP PO Box 1000, M/S 63-630 | (USA) (503) 685-3151 | VOICE Wilsonville, OR 97070 | (USA) (503) 685-3063 | FAX ----------------------------------------------------------------------- %! %% Patch to the setscreen operator to avoid unwanted behaviour and to %% increase speed, but at the expense of disabling patterning. Some %% applications set their own screens, but these generally look worse than %% the built-in ones in the Tektronix Phaser printers, so we want to use %% the internal ones. %% %% The patch simply executes the spot function procedure four times, once %% at each corner of the halftone cell, and throws the results of those %% executions away. Then all three arguments to setscreen are discarded. %% %% The proc would not have to be executed at all if it was not for those %% applications that set variables inside of the proc and refer to them %% outside of the proc (for determining the threshold gray level of a %% pattern). GEM applications and Broderbund TypeStyler do this. Normal %% setscreen operation could execute this proc thousands of times. %% %% This patch will only apply itself once. The patch can be circumvented %% by directly referencing the setscreen definition in systemdict, as in %% "systemdict /setscreen get exec" serverdict begin 0 exitserver /setscreen load type /operatortype eq % patch only if not patched already { /setscreen { .99999 .99999 2 index exec pop % execute proc, discard result .99999 -.99999 2 index exec pop -.99999 .99999 2 index exec pop -.99999 -.99999 2 index exec pop pop pop pop % discard setscreen arguments } bind def /setcolorscreen{12{pop}repeat}bind def (Setscreen patch downloaded) = flush } if %%EOF