Anti-aliasing explained

[QuickSilva]

Thanks for the replies, sorry I`m a bit late to respond but reading this has helped to clear a few things up. I`m slowly getting there I think. It`s also interesting to see some artists work that still looks great yet hardly uses any AA, Kenneth Fejer springs to mind as does Konjak. I actually really like some none AA work as it retains a sharp clean look. Some people seem to use it well though and maintain that clean look. It`s a good skill to know and one well worth mastering.

Jason.

[ptoing]

Speaking of no AA stuff. Metal Slug has hardly any AA. Nor has Dodonpachi (well at least not in the sprites much). Many games have not really much AA and still look good. It's not like if you have shit art and you AA it, it will get better. If you know how to draw you should be able to make stuff good without AA.

[.TakaM]

Only real trick I have is not to AA 90degree lines, as in

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    .
       .
          .
              .   

Assuming you meant 45º lines, as in

I've always disagreed with not AAing these lines, at least under all circumstances.
As most of us will agree, AAing is mostly math, and using simple math it's easy to see that a 45º line is not actually "1 pixel thick":

If you were to move the edges of the diagonal line to fill in the gaps- it becomes much clearer

You can see that a diagonal line only occupies 60% the width of a straight line. (as in working with the physical orientation of pixels)
This is why over long stretches of a 45º line I think it's appropriate to AA, preferably 40% of the colour of the line itself.
However, it's not really necessary over short lines, or when lines are several pixels thick

[Indigo]

takaM - I couldn't agree with you more.  In fact I was going to write a quick article type thing about it.  Mathematically 45 degree lines should be AA'd.  The AA is very light, so if your color ramp doesn't support it, it's probably a closer approximation to not AA them at all.  But if your ramp does allow for it, it definitely makes sense.

[QuickSilva]

I completely agree with ptoing that AA-ing will not save poor artwork it can however lift already good artwork to a higher level if done well. It certainly has its uses.

Jason.

[Jad]

Super quickie:

If you want equal line weight on a single line, AA everything

If you're speaking of the edges of big shapes, AAing diagonal lines can be redundant.

[Gil]

All this theory... I just push pixels 'til it looks good.

[Jad]

Actually I do too.

Then I formulate my ideas about techniques into words O:! And then we discuss it when we feel like it.

Actually I had a two-year long break from pixel art and when I started again I was on a level I could not have imagined myself to be on because of:

traditional practise (me sketching things with pencil; playing with other mediums in high-school, etc)

lurking at pixelation (reading threads like this, which made me do things in a completely different way once I started pushing pixels)

So yes. Theory is fucking awesome goddamnit.

I guess that because kind of the whole purpose of this forum is discussing and discovering the theory of pixel art your post just seems .. completely off to me. >:

[Gil]

Of course it is, but only when abstracted. You need to use theory so you can guide your thoughts later, not just looking stuff up you need at that point. Art is all about studying and a lot of theory goes into that.

[Shrike]

Only real trick I have is not to AA 90degree lines, as in

 .
    .
       .
          .
              .   

Assuming you meant 45º lines, as in

I've always disagreed with not AAing these lines, at least under all circumstances.
As most of us will agree, AAing is mostly math, and using simple math it's easy to see that a 45º line is not actually "1 pixel thick":

If you were to move the edges of the diagonal line to fill in the gaps- it becomes much clearer

You can see that a diagonal line only occupies 60% the width of a straight line. (as in working with the physical orientation of pixels)
This is why over long stretches of a 45º line I think it's appropriate to AA, preferably 40% of the colour of the line itself.
However, it's not really necessary over short lines, or when lines are several pixels thick

xD
Yeah, I meant 45 degree lines, and my periods were totally inaccurate.  Sorry about that, but still I generally don't AA those, unless for a very gradual curve.  I guess I should try!  Thanks for catching me up, I'm still a newb at heart.

Also, I agree with Jad.  Like always.   
Toodles!
Shrike