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  Anti-Aliasing filter (Message 1 to 7 of 7)  
From: Ken
Subject: Anti-Aliasing filter
Date: 2 Nov 1998 18:24:22
Message: <363E3EE7.CDD858E6@pacbell.net>
Need a post processing anti-aliasing filter ?
This is one I developed myself and it works pretty good.
I call it JagRedux. Try it. If you like it use it. If
not delete away.

In PSP there is the user definable filters section. Add the following
in to the matrix.


 0    0   -1    0    0
 0    0    3    0    0
-1    3    7    3   -1
 0    0    3    0    0
 0    0   -1    0    0

division 15
bias      1


Ken Tyler


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From: Nieminen Mika
Subject: Re: Anti-Aliasing filter
Date: 3 Nov 1998 04:11:21
Message: <363ec8b9.0@news.povray.org>
Ken <tyl### [at] pacbellnet> wrote:
: Need a post processing anti-aliasing filter ?
: This is one I developed myself and it works pretty good.
: I call it JagRedux. Try it. If you like it use it. If
: not delete away.

  Is this antialiasing or blurring? They are NOT the same thing.

-- 
                                                           - Warp. -


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From: Ken
Subject: Re: Anti-Aliasing filter
Date: 3 Nov 1998 05:57:50
Message: <363EE170.8C3610BF@pacbell.net>
Nieminen Mika wrote:

>   Is this antialiasing or blurring? They are NOT the same thing.
>
> --
>                                                            - Warp. -

  I prefer to think this is antialiasing not blurring or softening.
Check it out for yourself. I tried to keep the effect on the low
side and multiple passes may be required to achieve the desired
response.

If  YOU don't like it DON'T use it.
It's THAT simple.

Ken Tyler


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From: Nieminen Mika
Subject: Re: Anti-Aliasing filter
Date: 3 Nov 1998 11:14:21
Message: <363f2bdd.0@news.povray.org>
Ken <tyl### [at] pacbellnet> wrote:
: If  YOU don't like it DON'T use it.
: It's THAT simple.

  I didn't mean I don't like it. I just want to use the correct terms to
avoid misconceptions.
  You can't calculate antialiasing to a final image. You can only calculate
antialiasing when calculating the image itself. Antialiasing _adds_ infor-
mation to the image. It sees what is "between" the pixels.
  If you just soften the image after it's ready, you are not calculating
antialiasing because you don't know what is "between" the pixels. You have
only the pixels of the image and nothing more. You can average them to
achieve a similar effect to antialiasing, but that's blurring, not
antialiasing.
  I think using the right terms is good, so we can know what people is
talking about.

-- 
                                                           - Warp. -


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From: Margus Ramst
Subject: Re: Anti-Aliasing filter
Date: 3 Nov 1998 11:44:16
Message: <363F3307.B6B9F9A6@peak.edu.ee>
Well, I tried it out. It's not quite what I'd call antialiasing, since it works
uniformly all over the image. One can only get so far with a simple filter
matrix... Still, it does look much better than soften or blur.
One thing, though: it seems to bringhten the contours of objects (kinda like a
slight halo around them). Have you noticed?

Margus

Ken wrote:
> 
> Need a post processing anti-aliasing filter ?
> This is one I developed myself and it works pretty good.
> I call it JagRedux. Try it. If you like it use it. If
> not delete away.
> 
> In PSP there is the user definable filters section. Add the following
> in to the matrix.
> 
>  0    0   -1    0    0
>  0    0    3    0    0
> -1    3    7    3   -1
>  0    0    3    0    0
>  0    0   -1    0    0
> 
> division 15
> bias      1
> 
> Ken Tyler


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From: Ken
Subject: Re: Anti-Aliasing filter
Date: 3 Nov 1998 15:12:55
Message: <363F638D.218FE3C3@pacbell.net>
Margus Ramst wrote:

> Well, I tried it out. It's not quite what I'd call antialiasing, since it works
> uniformly all over the image. One can only get so far with a simple filter
> matrix... Still, it does look much better than soften or blur.
> One thing, though: it seems to bringhten the contours of objects (kinda like a
> slight halo around them). Have you noticed?
>
> Margus

It does seem to work better on very busy scenes as opposed to simple
objects. The halo effect is not something I have noticed.

Ken Tyler


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From: Ron Parker
Subject: Re: Anti-Aliasing filter
Date: 3 Nov 1998 16:23:56
Message: <363f746c.0@news.povray.org>
On Tue, 03 Nov 1998 12:11:57 -0800, Ken <tyl### [at] pacbellnet> wrote:
>
>It does seem to work better on very busy scenes as opposed to simple
>objects. The halo effect is not something I have noticed.
>
>Ken Tyler


The halo effect is because the -1s in the matrix are similar to a
sharpen filter.  The simplest sharpen filter is something like

 0 -1  0
-1  n -1
 0 -1  0

which will change the intensity of a pixel in a way that is roughly
proportional to the gradient at that point.


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