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Tch
Account closed
Registered: Sep 2004
Posts: 512 |
Anti-Aliasing
I thought I understood but I am confused again.
What the hell is Anti-aliasing? |
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jailbird
Registered: Dec 2001
Posts: 1576 |
A quite rough definition would be that anti-aliasing is a tehnique to smooth up stairway-like curved edges (mostly produced by the combination high contrast and low resolution) by putting middle-value colors inbetween different x/y pixel levels. If you'd like a visual example on your PC, load up Photoshop, write something with the text tool and turn antialiasing to 'none'. You'll note the difference immediately.
Frankly, I have not seen Tch using a-a too much (UFLI in general), however, that haven't took out a single bit out the very high technical value of his amazing works. That's just an example that antialiasing is not always necessary for making extraordinary graphics.
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Bizzmo
Account closed
Registered: Mar 2005
Posts: 82 |
And I bet someone is going to try and tell me that "dithering" is just putting two different colours/shades in alternate pixels... |
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TDJ
Registered: Dec 2001
Posts: 1879 |
I'm still waiting for somebody to explain to me what 'pixelling' actually is. |
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Oswald
Registered: Apr 2002
Posts: 5022 |
http://en.wikipedia.org/wiki/Antialiasing
(and lookie what have I found http://en.wikipedia.org/wiki/Pixel_Art one of the example images is a c64 koala :D ) |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
"Pixeling" seems like a C64 scene term to me, just like "part" (demopart). "Parts" are called "Pages" in the Atari scene for example :) |
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HCL
Registered: Feb 2003
Posts: 716 |
You can think of anti-aliasing as faking a higher resolution, thus each pixel is a merge of 2x2 or 4x4 pixels. If you apply that idea on an outline, each pixel gets some amount of the forground object color, and some other amount of the background color. Merge that in your head and choose the nearest usable color :).
That's in fact exactly how a-a works in some rendering programs. Generate a picture in 640x400 and reduce it down to 320x200 by merging pixels. Not really efficient but.. |
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JackAsser
Registered: Jun 2002
Posts: 1989 |
Anti-aliasing are the methods used to reduce the artifacts that arise from aliasing. Aliasing is something that you get when you sample a signal with a too low frequency. In the case of graphics and the C64, the image is made up of too few pixels to accuratly represent a smooth curve, i.e. the sample rate is too small to represent the ideal curve you like. Hence you get aliasing artifacts, in this case stairway patterns. There are many ways to reduce this aliasing and have already been explained in the previous posts.
There are extreme cases of aliasing artefacts when it comes to sound. If you for instance sample an ideal sinus with a too low frequency you can get faked high pitched sounds that are multiples of the frequency of the original sinus.
Google for antialiasing, aliasing, nyqvist frequency and sample theory. |
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jailbird
Registered: Dec 2001
Posts: 1576 |
Antialiasing is chaos theory - and pixelling is a C64 scener's way of expressing the love towards nice tits. |
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chatGPZ
Registered: Dec 2001
Posts: 11127 |
Quote:
"Pixeling" seems like a C64 scene term to me, just like "part" (demopart). "Parts" are called "Pages" in the Atari scene for example :)
i've heard "pages" from (mostly ntsc-) c64 dudes aswell :) |
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jailbird
Registered: Dec 2001
Posts: 1576 |
From the serious side.
C64 antialiasing differs a little than a machine generated smoothing explained on the wikipedia page. A graphician relies much more on his taste rather than mathematical theories or rules ;) Especially as we have this freaky x-stretched graphics mode which requires a bit different approach than the more usual technique based on square pixels. And this technique advances with practice just as any skill. From none or bad to professional. There is no ultimate way for making good smoothing I guess, different methods exist... And yes, it should be a common, basic knowledge, but I still see aliased low-res pictures released which would benefit quite a much by defeating those chunky edges.
Two basic examples:
^Aliased two color hi-res
^Anti-aliased by putting one alternate pixel after each edge to create the illusion of an extended, smoother offset. Looks much more effective on the C64, though.
^An aliased bright/semi-bright color will look quite stagged whatever you do. The tehnique from hi-res won't help too much.
^There you go, a two-level anti-aliasing which smoothed up the edges and now the curves look more round.
And I'd especially recommend to beginner pixel lovers to learn anti-aliasing first, good ways of dithering as the second step, and coloring at the end. This is mostly a must, IMHO. |
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