Printing: Gamma Correction (Adjusting the brightness)

Support knowledgebase (jsmeix_print-gammakorrektur)
Applies to

SuSE Linux: Versions up to (including) 7.3

Request:


You'd like to adjust the brightness of the colours of your printer

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.


Keywords: PRINTING, PRINTER, GAMMA, GAMMA CORRECTION, BRIGHTNESS

Categories: Frequently asked Questions , Documentation , Printer

SDB-jsmeix_print-gammakorrektur, Copyright SuSE Linux AG, Nürnberg, Germany - Version: 03. Nov 1999
SuSE Linux AG - Last generated: 14. Mär 2002 by wimer (sdb_gen 1.40.0)