AuthorTopic: Pixel Illusion  (Read 1055 times)

Offline AlexHW

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Pixel Illusion

on: February 21, 2018, 11:43:39 pm
I found something interesting.. This is what a patterned black and white image does when it changes scale. It reveals an underlying oscillation/duality present within the pixels that give the illusion of moving towards and away while the pixels expand along one dimension.

Please share your interpretation in this thread of why this phenomenon happens, as well as any related pixel illusions you may find.

Here is the pixel illusion:


I believe the black and white pattern causes a vibration/wave effect to occur when the dimensions are stressed- which produces the illusion of an extra dimension.

Offline AlexHW

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Re: Pixel Illusion

Reply #1 on: February 22, 2018, 12:01:50 am
Here is what it looks like if I add a rotation:


The result are various sub-rotation illusions emerging.

« Last Edit: February 22, 2018, 03:21:13 am by AlexHW »

Offline Indigo

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Re: Pixel Illusion

Reply #2 on: February 22, 2018, 01:41:17 am
You can try to find philosophical meaning in this if you want I guess, but what you're witnessing are simply Moiré patterns (interference patterns).  This happens when one pattern partially obscures a similar pattern - in this case the available pixels of the screen are obscuring the pixels of your pattern as you do various transforms.

here's a numberphile video about Moiré patterns
« Last Edit: February 22, 2018, 02:35:54 am by Indigo »

Offline AlexHW

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Re: Pixel Illusion

Reply #3 on: February 22, 2018, 02:17:15 am
Edit:
I removed all my theory related stuff as it seems not appropriate for the intentions of this thread.

I think it would be more interesting to focus on finding illusions in pixel art, as my examples help serve to do.
« Last Edit: February 22, 2018, 03:24:10 am by AlexHW »

Offline yrizoud

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Re: Pixel Illusion

Reply #4 on: February 22, 2018, 11:03:19 am
I think the first image's "zoom in/out" is caused by the Wagon-wheel effect

Offline AlexHW

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Re: Pixel Illusion

Reply #5 on: February 22, 2018, 04:08:37 pm
Nice find, yrizoud! I can see the similarities with that too. I wonder what else there is.

Offline ptoing

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Re: Pixel Illusion

Reply #6 on: February 23, 2018, 07:30:00 pm
Yeah, this has all to do with how things get scaled, like whether or not there is filtering and such.

In the original Doom engine, if you made a room that is really high and put a small repeating texture on it (like a switch) and went really far away you would at once point see the whole massive wall look like a giant switch at the right distance. Same effect.
There are no ugly colours, only ugly combinations of colours.

Offline 0xDB

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Re: Pixel Illusion

Reply #7 on: February 24, 2018, 08:43:06 am
see also: https://en.wikipedia.org/wiki/Aliasing (what we see here is called "Spatial Aliasing"). Just wanted to add this as I often see "Aliasing" being used synonymous with "Jaggies" which are just a specific instance of aliasing (an umbrella term for all kinds of sampling errors in signal processing).

Offline AlexHW

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Re: Pixel Illusion

Reply #8 on: February 24, 2018, 04:25:42 pm
Cool, here's a quote from that page
Quote
Like the video camera, most sampling schemes are periodic; that is, they have a characteristic sampling frequency in time or in space. Digital cameras provide a certain number of samples (pixels) per degree or per radian, or samples per mm in the focal plane of the camera. Audio signals are sampled (digitized) with an analog-to-digital converter, which produces a constant number of samples per second. Some of the most dramatic and subtle examples of aliasing occur when the signal being sampled also has periodic content.
I'm wondering if there are any examples of aliasing when there are no periodic characteristics. I'd be really interested in seeing that.

edit:
If a cross-section of multi-dimensional space produces aliasing. It seems as if the aliasing is one uniform dimension of space that we refer to as noise.
« Last Edit: February 24, 2018, 06:20:41 pm by AlexHW »