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# I know what aliasing is
in a digital signal sense, but have no idea how it applies to pictures

I know someone who would know though. I can ask if you'd like
(I helped save b3ta! kitty meow meow, Mon 15 Dec 2003, 18:45, archived)
# In 3D projects (videogames etc.)
It refers to polygons whos edges don't appear to be straight, as in the renderer draws them as jagged lines instead, also know as aliasing. The same thing applies to pictures, ie in photoshop when you draw a line with the line tool, it isn't smooth, because photoshop works on a pixel basis, so the line can only be jagged, because the pixels are essentially square. anti-aliasing (in 2 and 3D) refers to filters that make the line appear straight,often meaning it blurs it slightly so the sharp edges fade.

sorry, just spent the like the past 10 hours working with the Halflife engine, trying to make some images appear smoother when they were scaled and partly transparent
(TheTruffleShuffle, Mon 15 Dec 2003, 19:13, archived)
# not seen you in ages!
I was thinking about a more mathematical explanation, not about what it really does.

where've you been?
(I helped save b3ta! kitty meow meow, Mon 15 Dec 2003, 19:16, archived)
# I moved to England
:)

actually, I'm just over here on an exchange program.
(TheTruffleShuffle, Mon 15 Dec 2003, 19:20, archived)
# cool
I'm jealous.
(I helped save b3ta! kitty meow meow, Mon 15 Dec 2003, 19:21, archived)
# It's fantastic,
but I barely have time to lurk, let alone shop anything right now.
(TheTruffleShuffle, Mon 15 Dec 2003, 19:24, archived)
# as long as you're enjoying yourself :)
Everyone I know is over there. I wish I knew how to make freinds in real life
(I helped save b3ta! kitty meow meow, Mon 15 Dec 2003, 19:25, archived)
# Well anti-aliasing is actually a broad term for any process which removes aliasing from an image ...
Like I say below, super-sampling and bi-linear filtering are two of the most common.
In things like font rendering you can calculate for each pixel not just whether it's in or out the glyph (character), but what fraction of the pixel is in or out. For a pixel 30% in the character, you fill it 30% grey.
The human eye will actually perceive a blury line/edge as straighter and finer than an on/off pixel edge when it's diagonal.
In fact recently there's been a more interesting improvement in anti-aliasing for fonts on LCD screens. You now get anti-aliasing routines for fonts which renders little bits of red or blue along the edge of the fonts (which is better than grey because the red cell in the pixel is on the left and the blue cell is on the right*).
Try zooming in on small fonts in XP on a laptop, you might be able to see it - it looks crap close up, but really makes things look sharp when viewed normally.

* - On some LCD's it's BGR etc... but you get the point.
(I helped save b3ta! Hagbard ... it's been a long time., Mon 15 Dec 2003, 19:28, archived)
# hmmm
still doesn't tell me the structure of the filter that it goes through. I understood all that before :)
(I helped save b3ta! kitty meow meow, Mon 15 Dec 2003, 19:31, archived)
# There is no 'the' filter, it can be one of a hundred things.
Photoshop is probably doing something like bi-liinear or bi-cubic filtering whereas 3D graphics cards can also do semi-translucent edges and supersampling when rendering.
(I helped save b3ta! Hagbard ... it's been a long time., Mon 15 Dec 2003, 19:34, archived)
# this is at a much higher level than I understand
I've heard of these, but I'm used to thinking about filters differently, at a very introductory level.

(I helped save b3ta! kitty meow meow, Mon 15 Dec 2003, 19:36, archived)