9/29/2009

09-29-09 - Aliasing is Pretty

I made some images of aliasing/moiray patterns : (BTW inherent to these images is the fact that they don't look at all right except at full zoom since the image structure is created by the pixel grid sampling aliasing, so click through). You may be surprised to know what these are an image of.

Photobucket

Photobucket

Photobucket

Photobucket

Photobucket

Photobucket

Photobucket

....

Answer : these are pictures of sin( x^2 + y^2 ) , that is, sin( r^2 ) a very simple radial trig function. You don't see the function at all, the images are 100% aliasing as the radial sin is scaled to very high frequency.

16 comments:

Autodidactic Asphyxiation said...

Pretty pics, and bonus: best spelling of "moire" ever!

What happens when you generate an image of a zone plate?

http://en.wikipedia.org/wiki/Zone_plate

That way, you can actually see at what frequencies/orientations the aliasing occurs.

cbloom said...

Oh the fucking Google slow to login comment ass bullshit is killing me.

cbloom said...

The fact that firefox wipes your entry boxes when the page changes is what really makes it awful. Jebus.

cbloom said...

Anyhoo - I think this is a zone plate if I'm reading that right. I'm plotting sin(r^2), the zone plate is 1+cos(r^2) , same thing.

cbloom said...

Flickr zoneplate pool has some great stuff

http://www.flickr.com/groups/zoneplates/pool/

Autodidactic Asphyxiation said...

Oh, me dumb. Yeah, of course that's what you're doing...for some reason I managed to confuse r and r^2. r dr r.

The optical properties of zone plates are cool. Actually, Fourier optics are cool, in general.

Jon Olick said...

++nice link

Thatcher Ulrich said...

Speaking of Flickr, what would happen if you dumped Photobucket and hosted your images on a less obnoxious service?

The images look cool -- but they might look even cooler with fewer Flash ads around them.

cbloom said...

Yeah, Photobucket was an experiment that is not going great. The plus is you can host large lossless photos for free.

Flickr sucks without a paid account because of the limits. Picasa is just malware. So I'm not sure what else to use.

cbloom said...

BTW I didn't even know photobucket had ads. I flashblock and adblock , I never saw them. I hate it because I have to click through a bunch of annoying page reloads and the layout sucks.

Aaron said...

Pay a little bit for an unlimited hosting plan somewhere. Every few weeks Dreamhost has some sort of deal on unlimited storage/bandwidth forever plans for less money than you 'spent' trying to find a free service that does not suck (pirate bay image hosting maybe?). They give you shell access and everything.

Aaron said...

Or you can use mine. I think I have like 3 gigs free or something, you just gotta pay for a domain name and I can pop you on my account. Er no wait, I just checked and apparently I got silently upgraded to unlimited storage and bandwidth.

Thatcher Ulrich said...

Hrm, I assumed you could upload to Picasa without installing the malware. Unlimited storage on Pflickr sounds pretty good!

Thatcher Ulrich said...

Yeah, I just checked, you can definitely upload to picasaweb.google.com without installing any client software. Dunno if they do lossless hosting.

cbloom said...

Hmmm, I guess I could use Picasa just as a file server. I like the way Photobucket gives me HTML code with a thumbnail and a link to the full size image.

Vincent Scheib said...

Mmm, I love the moire. A little moire app from years ago: http://www.scheib.net/school/238/imoire/

old rants