Timeline for What causes aliasing?
Current License: CC BY-SA 3.0
17 events
| when toggle format | what | by | license | comment | |
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| Aug 24, 2015 at 21:10 | comment | added | joojaa | Please note human eyes are also discrete. The sensors in the eye are both timewise and sample positionwise discrete. Not in a predictable electronic way but discrete nonetheless. | |
| Aug 21, 2015 at 11:05 | comment | added | Luke | @Luaan Ahh, I understand now. The moire pattern is visible but the aliasing that causes it is not. Sorry. | |
| Aug 21, 2015 at 10:57 | comment | added | Luaan | @Luke You misread - I was saying Moire patterns are easily visible to the eye. But not all Moire patterns are also aliasing, though the effect is similar in some ways. | |
| Aug 21, 2015 at 10:46 | comment | added | Luke | @Luaan Are you sure moire patterning is not visible with the naked eye? I am sure I have seen it on, for example, chain link fences... I remember distinctly on one occasion because I thought to myself "that's a moire pattern" after having learned about them recently. Though, perhaps I had misidentified the phenomenon... | |
| Aug 20, 2015 at 11:37 | history | edited | jhocking | CC BY-SA 3.0 |
trivial edit to let people cancel votes
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| Aug 20, 2015 at 11:33 | vote | accept | Kruncho | ||
| Aug 20, 2015 at 8:50 | comment | added | Luaan | @Kruncho Well, it happens on that level too, since light is quantized (i.e. composed of discrete "particles") - however, at visible-light scales, this is invisible to human sight (it's improtant in certain optical devices, though). If you want a "physical" example of something similar and easily visible to the eye, have a look at the Moire effect (some Moire patterns are in fact caused by aliasing, though that's again not visible to humans in nature). Any digital signal processing is "vulnerable" to aliasing, and the universe seems to be digital - it's just that the scale is a lot different. | |
| Aug 19, 2015 at 21:47 | comment | added | pabouk - Ukraine stay strong | @MikeScott: Even with irregularly arranged pixels the aliasing will show up. :))) The important condition for aliasing to appear is that the maximum frequency of the original signal (the original image) is higher than 2*(1/T) (where T is the interval between the samples = the distance between the pixels). --- When the original image has sharp edges (like the black line on a white background) then its maximum frequency is infinite. | |
| Aug 19, 2015 at 18:36 | comment | added | jhocking | You're getting hung up on the word "square" when that's just a descriptor for "grid". | |
| Aug 19, 2015 at 18:33 | comment | added | Mike Scott | @jhocking "Square grid" won't cut it either. You'd still get aliasing (looking a bit different) if your pixels were arranged in a hexagonal grid. All that matters is that the pixels are arranged in a regular pattern and are of non-zero size, and both of those conditions are true for any conceivable display technology. | |
| Aug 19, 2015 at 18:26 | history | edited | jhocking | CC BY-SA 3.0 |
added 29 characters in body
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| Aug 19, 2015 at 18:24 | comment | added | jhocking | okay I'll reword it to "a square grid of pixels" | |
| Aug 19, 2015 at 18:05 | comment | added | Fuzzy Logic | @jhocking A pedantic correction: the squareness of the pixels is not actually relevant. Aliasing would happen just the same if each pixel were round dots of all the same size. | |
| Aug 19, 2015 at 17:57 | comment | added | Fuzzy Logic | @Kruncho Never be sorry for being wrong, unless you are teaching others your mistakes! Only be sorry when you don't try to understand or are unwilling to be corrected. Your mistake actually helped to clarify what exactly you were asking to know about: ('how' does aliasing happen in computer graphics?). Btw, while this answer is best to illustrate the what, how and why, it is a numerical issue. You could think of it as a limitation of trying to represent fractional numbers using only whole integers. There is no half pixels, etc. So you end up with blocky looking images. | |
| Aug 19, 2015 at 14:13 | vote | accept | Kruncho | ||
| Aug 20, 2015 at 6:12 | |||||
| Aug 19, 2015 at 14:13 | comment | added | Kruncho | Thank you for the answer. By physical I was thinking of the light and maybe an optical effect sorry for the mistake | |
| Aug 19, 2015 at 12:37 | history | answered | jhocking | CC BY-SA 3.0 |