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Re: Sometimes noise and resources about colours

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On Sun, 25 Nov 2012 22:43:20 +0100, Cecil Westerhof wrote:

> I am dabbling with postscript. I like it, but it take a lot of time. ;-)
> 
> The last 6 graphics at:
>     https://www.facebook.com/media/set/?
set=a.351549161549364.70328.100000828491269
> 
> (the first 6 in the list) I made with postscript. But I see some noise
> in some of them. How can I circumvent this. At the moment I use ps2pdf
> to make an pdf and then convert (from Image Magick) to make a png. I saw
> that it is in principal possible to make a png with ghostscript. Would
> that give better results.

I assume the "noise" you refer to are the "blobs" around the text glyphs. 
That looks to me like the effects of halftoning, because the output 
doesn't have enough colours to accurately portray the colours you've used 
in the Postscript.

Using ImageMagick, you almost certainly already are using Ghostscript, 
but you will have more direct control by calling Ghostscript directly, 
and you can leave out the ps2pdf step.

You can do something like:
gs -sDEVICE=png16m -r300 -o <output>.png <input>.ps

You can also replace "png16m" with png16, png256, png48, pngalpha, pnggray 
or pngmono, for different colour fidelities (lower fidelity == smaller 
file size). The  "-r" (resolution) option is something you probably want 
to read up on.

Most of the commonly used Ghostscript options are documented here:
http://www.ghostscript.com/doc/9.06/Use.htm

Chris

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Sometimes noise and resources about colours Cecil Westerhof <Cecil@decebal.nl> - 2012-11-25 22:43 +0100
  Re: Sometimes noise and resources about colours Chris <cjl@spamcop.net> - 2012-11-25 22:03 +0000
    Re: Sometimes noise and resources about colours Cecil Westerhof <Cecil@decebal.nl> - 2012-11-25 23:54 +0100
      Re: Sometimes noise and resources about colours Chris <cjl@spamcop.net> - 2012-11-26 09:50 +0000
        Re: Sometimes noise and resources about colours Cecil Westerhof <Cecil@decebal.nl> - 2012-11-26 21:43 +0100
          Re: Sometimes noise and resources about colours Chris <cjl@spamcop.net> - 2012-11-26 21:00 +0000
            Re: Sometimes noise and resources about colours Cecil Westerhof <Cecil@decebal.nl> - 2012-11-26 23:19 +0100
              Re: Sometimes noise and resources about colours Chris <cjl@spamcop.net> - 2012-11-26 22:36 +0000
                Re: Sometimes noise and resources about colours Cecil Westerhof <Cecil@decebal.nl> - 2012-11-27 00:41 +0100
          Re: Sometimes noise and resources about colours Cecil Westerhof <Cecil@decebal.nl> - 2012-11-26 22:15 +0100

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