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Re: Sometimes noise and resources about colours

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Op zondag 25 nov 2012 23:03 CET schreef Chris:

>> 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.

Yes.


> 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.

But I am only using two colours.


> 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

The first try does not look promising. With the -r300 I get a to big
picture. When I leave it out the size is correct. But I still have the
noise. Also the kerning is wrong. The letters are to close together
now.

The command I am using is:
    gs -sDEVICE=png16m -o keepYourHead2.png keepYourHead.ps

The 2 is to keep the file from the other generate to compare them.

The generated files are posted at:
    http://decebal.nl/postscript/keepYourHead.png
    http://decebal.nl/postscript/keepYourHead2.png


> 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

I'll look into them.


By the way, I even see noise in the pdf, but less and only under the
text:
    http://decebal.nl/postscript/keepYourHead.pdf

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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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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