Printing: Gamma Correction (Adjusting the brightness)

Support knowledgebase (jsmeix_print-gammakorrektur)

SuSE Linux: Versions up to (including) 7.3

Request:

Procedure:

Since SuSE Linux 8.0 see the "Reference" manual.

Up to SuSE Linux 7.3:

1. You'll need to change the file /var/lib/apsfilter/preloads/gamma.ps
   Assuming your printer uses CMYK colors, just remove the % sign from the line you'd like to use as follows:

   %%   CYAN      MAGENTA     YELLOW      BLACK
   %{0.217 exp} {0.217 exp} {0.217 exp} {0.217 exp} setcolortransfer
   %{0.256 exp} {0.256 exp} {0.256 exp} {0.256 exp} setcolortransfer
   {0.333 exp} {0.333 exp} {0.333 exp} {0.333 exp} setcolortransfer
   %{0.450 exp} {0.450 exp} {0.450 exp} {0.450 exp} setcolortransfer
   

   The values must be between 0.001 and 0.999

   You can test it on the screen entering the command below in a terminal window provided you use the X Window System.
   (Please note that the following must be on one line.)

   gs /var/lib/apsfilter/preloads/gamma.ps
   /usr/share/ghostscript/VERSION/examples/colorcir.ps 
   

   where VERSION is your Ghostscript version (e.g. 5.10 or 5.50).
   If the colours are completely wrong you may use one of the Ghostscript devices x11cmyk, x11cmyk2, x11cmyk4 or x11cmyk8 :

   gs -sDEVICE=x11cmyk /var/lib/apsfilter/preloads/gamma.ps
   /usr/share/ghostscript/VERSION/examples/colorcir.ps
   

   To finish press [Ctrl]+[C] in the terminal window where you entered the command above.

2. Enter the file /var/lib/apsfilter/preloads/gamma.ps in the variables PRELOADS in the appropriate /etc/apsfilterrc... file as follows:

   if [ "$COLOR" = "mono" ] ; then
   #   GS_FEATURES="-dBitsPerPixel=1"
      PRELOADS=""
   else
   #   GS_FEATURES="-dBitsPerPixel=24"
      PRELOADS="/var/lib/apsfilter/preloads/gamma.ps"
   fi
   

   It shouldn't matter if you use PRELOADS="gamma.ps" or PRELOADS="/var/lib/apsfilter/preloads/gamma.ps"

   Regarding "the appropriate /etc/apsfilterrc... file" see
   Installing a printer since SuSE Linux 6.4.