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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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JackAsser
Registered: Jun 2002
Posts: 1990 |
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: 11146 |
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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ptoing
Registered: Sep 2005
Posts: 271 |
Heh, i totally forgot that my Yus-Bird pic is on Wikipedia, have been asked by a wiki maintainer quite some time ago if it's ok to put it there, and there can never be enough c64 gfx anywhere on the web :)
About the antialiasing, the methong Jailbird described on the hires example also works in lores but only in vertical antialiasing. And i have to say that in most cases it's is not necessary or even bad to aa 45 degree lines, same goes for are "45 degree" line of wide pixels, as one will only blur the line and not actually make it appear smoother.
Also, for a pixel artist aa should be a form of meditation, it is for me at least in most cases :D |
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jailbird
Registered: Dec 2001
Posts: 1576 |
Quoting ptoingAbout the antialiasing, the methong Jailbird described on the hires example also works in lores but only in vertical antialiasing.
Oh yes, you're right. Actually, it will work sometimes even in horizontal smoothing. Not so usual as the color-based a-a, but sometimes it's needed in low-res too - mostly when the pixeller runs out of colors ;) On the example I have included here, there's no way that the technique from hires would help. :)
Quoting ptoingAnd i have to say that in most cases it's is not necessary or even bad to aa 45 degree lines, same goes for are "45 degree" line of wide pixels, as one will only blur the line and not actually make it appear smoother.
Yeps, right. It will make the lines thick and smudgy. Which takes us back to the taste of a graphician, to differentiate good/bad smoothing and if anti-aliasing is necessary at all. A machine or an algorythm couldn't do that.
Quoting ptoingAlso, for a pixel artist aa should be a form of meditation, it is for me at least in most cases :D
For me, aa is more fun than relaxation. Not the fun like having a beer and a chat with someone I love, more like the fun when riding a roller coaster and puking out my guts. :)
But your pictures really represent a general meditated approach. Adoreable style! |
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Tch
Account closed
Registered: Sep 2004
Posts: 512 |
Thank you everybody! 8D
It seems I understood it correctly afterall.
The second example Jailbird showed (thanx for that!) is a technique I almost always use.
The other one I am not too fond of. (hedgehog) ;)
AA in UFLI is something else altogether.
I started of with doing it,but it looks -in most cases- better without.
That´s because in UFLI you are very limited with colours.
And as I´ve not yet used black for the sprites,it is only possible to AA a smal portion of the pic.
Hence it makes more sense to do none at all. ;) |
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Monte Carlos
Registered: Jun 2004
Posts: 351 |
Please don't anti-alias horizontal or vertical lines.
That's what i consider normally as too much a.a. because
it looks like an outline.
Monti
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Monte Carlos
Registered: Jun 2004
Posts: 351 |
Perhaps this is the reason, some people
dont like a.a. too much.
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Wile Coyote
Registered: Mar 2004
Posts: 646 |
Quote: "Pixeling" seems like a C64 scene term to me, just like "part" (demopart). "Parts" are called "Pages" in the Atari scene for example :)
no it's not. Pixeling means just that, Pixeling. To place a pixel down one by one.
The moment pixels are placed onto he screen using any other method, then it is no longer pixeling :) |
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