# Talk:Moiré pattern

WikiProject Physics (Rated C-class, Mid-importance)

## Bogus "Etymology" Section

The Etymology section (added on March 12, 2014) seems to be a prank. It links to an article about a supposed Swiss photographer named Ernst Moire who could not himself be photographed. I'm pretty sure that moire patterns are named after moire fabric, of which there is an etymology at http://en.wikipedia.org/wiki/Moire_(fabric), but I don't have a source for that. I'm just going to go ahead and delete the bogus Etymology section and if someone has a better source for how moire patterns came to be called that in contexts other than fabric, they can add one back in. — Preceding unsigned comment added by 64.223.163.225 (talk) 02:17, 19 March 2014 (UTC)

Ernst Moiré was in fact a real person, and while he has been difficult to track historically - possibly due to the covering up of his legacy, as it was mostly linked with failure (especially in photographic printing processes) and not success, the patterning/effect is likely named after him. Cabinet Magazine has published an investigative article, and more can be found in the short background written by the researcher: The Moiré Effect by Lytle Shaw. I suggest that this a the true etymological connection, not at all bogus. Minaberowka (talk) 19:13, 27 December 2016 (UTC)

I think the conflation of moire with mura is bogus. The citation only deals with the Japanese translation of "mura"; it doesn't connect the two words. No claims are made for an etymological link between the two. The implication is that since the sounds are similar and since both words have something to do with visual artifacts, there is some etymological connection. Here's a quick citation showing that at least in the VR community aliasing (which is the heart of moire) is quite distinct from mura: https://www.roadtovr.com/whats-the-difference-between-screen-door-effect-sde-mura-aliasing-vr-headset/ — Preceding unsigned comment added by 2620:0:1002:1000:4A0F:CFFF:FE67:124 (talk) 00:17, 10 January 2020 (UTC)

## Old stuff not previously in a section

I deleted the following text because the explanation seemed questionable:

 "[moiré patterns sometimes occur when scanning halftones],
when the image interferes with itself on either side
of the scanner's glass surface."


I wonder whether this explanation is a fact, or only a theory. Another possible explanation is aliasing from undersampling the halftone pattern. Jorge Stolfi 20:52, 24 Mar 2004 (UTC)

From personal knowledge, scanners themselves are scanning according to a pixelated grid. The moire pattern in this case is the interference between the halftone and the scanner's raster.

The two above concepts are both correct. Scanners scan in lines. The spacing of those lines combined with halftone patterns creates moire patterns.

Should this article include some description (and example?) of the use of moiré patterns in 1960's pop art? [[User:GK|gK ¿?]] 06:33, 18 Nov 2004 (UTC)

common in lamps of the 60s and 70s had concentric spirals of differing pitch. One spiral is rotated and moire patterns emerge. Beer companies also made really interesting lamps that used moire patterns to simulate water flowing.

Moire was merged into this article. JRM 15:07, 2004 Dec 3 (UTC)

## Moire in art reproduction

Moire patterns can ocur when items at a regular frequency are not at proper angles to generatee a pleasing pattern. Yes, scanning screened images is a prime example of how moires occur in the reproduction industry. --Dkroll2 17:29, Dec 27, 2004 (UTC)

In everyday life.... I first observed moire patterns in fences. When you drive parallel to a chain link fence that has another parrellel chain link fence behind it, you can see large diamond shapes moving across the fence. They are moire patterns. They are diamond shapes because the chain links are diamond shaped. Circular grating creates circular moire patterns.

Helicopter blades moving at high speads create a virtual moire pattern. It is an illusion that makes the blades appear to spin in the reverse direction. The illusion is a moire pattern created by the speed of the blades in relation to the sampling speed of the human eye.

• I have to comment on this. You see the effect only in a video or film rendition of the helicopter, not in "real life". The effect is due to video and film "dividing" time into discrete fragments, or frames. The human eye doesn't do this. However, due to our persistence of vision, we see the effect when viewing the record. Just my two cents... --Janke | Talk 16:01, 7 August 2005 (UTC)
Not true. Look at a spinning tyre. It does appear to spin backwards. This is, however, not Moire interference but the stroboscopic effect
Only on film or video, or if the tyre is illuminated with a strobe lamp or other pulsed light source. With incandescent illumination and direct vision, the tyre does not appear to rotate backwards. I agree with you though that this is the stroboscopic effect, not a moiré pattern. --Srleffler 18:27, 15 March 2007 (UTC)
Just for the record, there is no such thing as "sampling speed of the human eye". The eye does not sample. Unless there were some new discoveries in that field, in which case I welcome links.

--Xerces8 (talk) 10:02, 28 August 2014 (UTC)

I commented out one of the links at the bottom of the page because it is broken. The site still exists, however, so I imagine that the info is still out there, but someone needs to track it down and fix the link.

## Moirés in digital images of TV screens

Couple of points/questions:

• The arrow marks a scan line, but I belive the moire pattern from this is just another example of the next point.
• The remaining patterns, I believe, are not necessarily due to "interference" but that the resolution of the CCD is insufficiently small to satisfy the sampling theorem. It's not interference, but aliasing.

Cburnett 06:02, August 6, 2005 (UTC)

The camera used was 5 megapixels, so there are more than enough pixels for interference to occur. The uploaded image is reduced in size. The arrow actually marks where the first scan started - we see an image containing one partial, one full scan, interlaced. --Janke | Talk 06:11, 6 August 2005 (UTC)
Moire patterns are not a result of interference. Interference has no meaning in this context since it generally means noise, but noise doesn't cause moire patterns. 5 MP can still be insufficient to satisfy the sampling theorem.
In this case, the resolution of each pixel needs to be less than half the width of the black border around a pixel since it's the "highest frequency". Like I said, I believe it to be aliasing causing the moire patterns, not "interference" (please define this if you intend on using it further as well as in the article itself). Cburnett 04:53, August 10, 2005 (UTC)
Better now? I removed "interference", which I originally used as a general term, not a technical one. Please feel free to clarify the text further. --Janke | Talk 15:38, 11 August 2005 (UTC)

Another thing: In the article it says "photographs of TV". Is this really the case for analog photography? I don't think so. Maybe, if that's not the case, the word "digital" should be inserted before "photographs". --2pecialsymbol (talk) 12:26, 15 April 2015 (UTC)

"taken with a digital camera" is what it says. Samsara 00:46, 16 April 2015 (UTC)

## another example of bad resampling

versus

Observe how the stripes on the first and last flags appear slanted as a result. Btyner 16:14, 17 May 2006 (UTC)

## Another example of a Moiré pattern

--Oden 23:34, 25 July 2006 (UTC)

## Interferometric approach

I think the Interferometric Approach section is exactly wrong, but I'd welcome comment on this.

The problem is that adding the two sine waves models what would happen if you projected two sine waves onto a screen. It does not model the effect of superimposing a transparent sine-wave pattern onto another (transparent or opaque) sine-wave pattern, which is what we're talking about in the rest of this article. To model superimposition we need to multiply the sine waves and not add them.

Multiplying two sine waves close in frequency gives you the sum of two sine waves: one at the mean frequency and one at the difference frequency. It is the difference frequency that (It's exactly the same effect as heterodyne or synchronous detection in radio receivers, only in space rather than in time).

Also, you can't use the sine function directly to denote degrees of transparency, because it can take negative values. Transparency should vary from 0 to 1, which can be done by using ½(1+sin) in place of sin.

My editing skills aren't up to altering the mathematical formulae on this page but in any case I thought people should have a chance to comment first.

JoeBruno 12:05, 22 August 2006 (UTC)

Yes, you are right, and the analysis shown doesn't explain why the low-frequency envelope appears as such a prominent signal. It's easy to fix by specifying that the physical model of overlying transparent objects is multiplication of their transmittances, and that the sinues are logs of transmittances, or (negative) densities. Then, the final result, the sum is still a density, and the envelop component leads to a real intensity signal at that frequency when the log is exponentiated to get an optical intensity back. Then you avoid issues of negatives, multiplying sines, etc., and can still use an interferometric approach. Maybe I'll work on it later... Dicklyon 16:25, 22 August 2006 (UTC)

Hi -- yes the interferometric part is horribly worng. I'll try to9do some work on it.Siw1939 (talk) 00:48, 18 July 2013 (UTC)siw1939

Hi again -- OK, the incorrect "interferometric approach" was deleted and totally replaced, and I think all the prior objections to the older stuff have been answered. Siw1939 (talk) 18:38, 20 August 2013 (UTC)

## Animated image removal poll

Moiré patterns formed as a result of interference of parallel lines rotated by an angle of 0° to 6°

I propose we remove from the article this visually obnoxious and distracting animation. Please response here with "*Support" or "*Oppose" followed optionally by a comment. Dicklyon 16:29, 22 August 2006 (UTC)

Hearing no objection, I'll take it out for now. If you object, say so or put it back. Dicklyon 20:30, 30 August 2006 (UTC)

what if it's a static gif that when clicked loads the animated version. its quite interesting seeing it animated - ryan 72.195.135.6 08:32, 11 April 2007 (UTC)

That can't work as described, because a click on an image always takes you to the image page, with the very same image (possibly larger), with copyright and other info. Notinasnaid 09:35, 11 April 2007 (UTC)

I'm with Ryan - once on the image page, the reader can "click on this image to see animation" that is visually fascinating and instructional.Vendrov 06:02, 27 August 2007 (UTC)

## pronunciation

someone should add the pronunciation of the word ... 'cause i dont know it

Sounds like as good a reason as any; in the meantime, try a dictionary. Dicklyon 23:17, 13 October 2006 (UTC)

but the dictionary wiki suggested i try here! you can see the predicament im in. and my speach is tomorrow!!

quick web search suggests "more-ay", "more-RAY", "moa-ray", "mwa-RAY", etc. Pick one. Dicklyon 20:58, 20 October 2006 (UTC)

Clearly too late now, but I'm fairly certain that this was discovered by someone who is French, so French pronunciation should be used. The last one above is correct, though the emphasis is wrong. Moiré = mwAR-eh or mwAR-ay

## Nonlinear interaction

I restored the removal of nonlinear. Moire patterns do not result when optical patterns are added linearly, as by the projection of two patterns onto one screen. They require a nonlinearity, which is how the difference frequency components can be generated when they are not present in the originals. The typical nonlinearity is an "and" or an "or" function, depending on how the patterns are combined. For example, a stack of two transparent patterns is transparent when the first is transparent AND the second is transparent. For ink on paper, a spot gets ink if either one OR the other pattern would have ink at that spot. Linear combination, pretty much the definition, does not generate new frequencies. Dicklyon 05:59, 10 January 2007 (UTC)

For completeness, I'm adding a comment here (I thought I already had) that I was the person who deleted the nonlinearity reference. I'm not yet convinced, but I will consult the reference. Thanks. Victor Engel 17:42, 10 January 2007 (UTC)
I would like to see more detail about the nonlinearity. For example, if both component images are themselves nonlinear, then of course, the combination image is likely to be nonlinear. It sounds like what's being suggested here is that if both component images are linear images and the combination is nonlinear, than moire will result. Is that about the size of it? Victor Engel 20:53, 10 January 2007 (UTC)
I'm not sure what you mean by the images themselves being nonlinear. Consider any real scene, like the original brick wall image in the article. Is it linear? Nonlinear? Does it matter? I don't think so. But if you multiply it by a grid of delta functions or sampling apertures to create samples of it, you get aliasing or moire pattern due to that nonlinear multiply operator. Viewing it through a wire mesh has the same effect, since the mesh interacts nonlinearly with the original scene, like sampling it does. But projecting the original image onto a screen, and then projecting an image of a wire mesh on the same screen will not create a moire pattern, since those images just add their intensities linearly; a nonlinear warp of that image could, however induce a moire, and it's possible that in some cases there might be enough nonlinearity in your eye to induce some weak moire; but it's still due to a nonlinear interaction of the patterns. Dicklyon 22:48, 10 January 2007 (UTC)
Interesting that you don't know what I mean by the images themselves being nonlinear since my original reason for removing "nonlinear" from the article was that it was not clear what was meant by that. It certainly didn't seem to follow from the link to the nonlinearity article. I'm still unclear whay you mean by nonlinearity as it relates to Moire. Victor Engel 04:41, 11 January 2007 (UTC)
Well, we have to go back to what it means to be linear. A function or system f(x) is linear if the response to a sum of inputs is equal to the sum of the responses to the the inputs separately. The photoreceptors in your eye are not linear, but to first order they're close enough over a range of stimuli to model them as linear in optical intensity. So if you have an optical pattern x and your eye's cones respond as f(x), and another pattern y to which you respond f(y), then if you project the sum of those patterns into your eye, you get x+y and respond as f(x+y) = f(x)+f(y). That sum of x and y that you projected into your eye is a linear combination, and your eye responds linearly, and sinusoids are the eigenfunctions of continuous-domain linear systems (see LTI system theory), so no new frequencies are generated in the process; to the extent that your eye is not really quite linear it may generate weakly some difference frequencies that you perceive as weak moire patterns. Now, take those same x and y and combine them with something other than a sum; say min(x,y) or max(x,y) or x*y. The resulting optical pattern has strong "distortion" terms, with sum and difference frequencies and such, and when you project that into your eye or a linear sensor system it will respond strongly to those frequencies that were not present in either x or y but are present in their nonlinear combination; that's how moire patterns are formed. The nonlinear articles alludes to these min, max, and times operators when it says "nonlinear systems is not subject to the principle of superposition, as linear systems are". Dicklyon 05:45, 11 January 2007 (UTC)
You call the interaction between the patterns non-linear. The description of the effect is non-linear (with its quadrates and sines), but not the interaction. You mention step funtions and sampling rates: these may be discontinuous but that does not make them non-linear in the sense that the term is commonly used nowadays in dynamics. So I say remove this adjective from the intro, and just speak of "interaction of the optical patterns". Tom Peters 23:12, 10 January 2007 (UTC)
I did not mention either step functions or sampling rates. And the point of the impulse functions or sampling apertures was not their discontinuity, but rather their effective multiplication. Consider for example a mesh of fuzzy holes, with 0 transmission in the mesh lines, 1.0 in the centers of the holes, and varying smoothly and continuously from 0 to 1 around the edge of the holes. Lay that over another pattern, or illuminate a pattern through it, and you have effectively a product, a nonlinear combination of the two patterns, which will likely give rise to a moire pattern. Try it. Then, try projecting two patterns from two overhead transparency projectors onto one screen, so the optical intensities combine linearly, and you'll see that you can't make a moire pattern that way. You can do such experiments in photoshop if you're careful and knowledgeable enough, but since by default it does operations in the nonlinearly gamma compressed space, it's not so easy to simulate linear interactions of optical patterns there. Dicklyon 05:45, 11 January 2007 (UTC)
A moiré pattern, formed by two sets of parallel lines, one set inclined at an angle of 5° to the other
Take a look at the animation above, or this still version that's easier to analyze. What do you see? Step way back until you can't see the lines at all any more. Do you see just a gray area with some bright stripes running across it? I do. What makes those stripes bright? If you look carefully, you can see that there are fewer black pixels in those bright rows, because where the lines land on top of each other you only get 1 black pixel instead of the 2 that you get in other rows. In the animation, the light stripes follow the places where the lines overlap each other and give less blackness than when they don't. This low-frequency pattern of light stripes in gray is not in the original fine stripe patterns--it is induced by the nonlinearity, which you can take to be min(x,y) if x and y are optical intensity, or max(x,y) if x and y are an amount of ink, or x*y if x and y are 0 for black and 1 for white. But there's no way that a combination like x+y would generate such a pattern, because when you'd stand back far enough to blur it out there'd be nothing left but the sum of the average gray values of x and y. Get it? Dicklyon 05:55, 11 January 2007 (UTC)

Here are some more refs: [1] [2]. They both indicate that if you combine patterns nonlinearly you get a strong moire, and they also concede that if you combine them linearly there is still a weak effect due to perceptual effects; this is still a nonlinear interaction, only it's in your eye, as I said before, and it usually won't be enough to notice.

My little brother once did a project on moire that got written up in Scientific American's amateur scientist column, circa 1970, in which he photographed white 3D shapes through a grid of strings, and also illuminated through the strings, so the camera saw the nonlinear occlusion by strings of shadows of strings on the object, the result being moire fringes that traced out contours of the object. This is sort of like what came to be known as "structured light", a technique invented by Peter Will at IBM about the same time, iirc, to give machine vision cameras a way to see 3D structure. If we could find that old article, it might have an explanation worth quoting. Or maybe some of the old Edmund Scientific moire pattern kits have a good explanation. Dicklyon 06:11, 11 January 2007 (UTC)

Here's a PDF of a paper that analyzes the heck out of moire patterns caused by "superposition". He doesn't use the term nonlinear, but models reflectance or transmittance as numbers from 0 to 1 and "Since the superposition of black and any other shade always gives black, this suggests a multiplicative model for the superposition of monochromatic images." The multiplicative model is nonlinear, and an additive (linear) model in his Fourier approach would lead to no moire at all, so it pretty much supports the point without saying so. Another one I looked at talked about "intersection" of the patterns (I guess me means a logical AND function, again highly nonlinear). Dicklyon 06:38, 11 January 2007 (UTC)

## Merge?

Someone has created the article Line moiré, which contains material that overlaps with this article. Perhaps they should be merged. On the other hand, that new article may be original research, as the references and external links are all to unpublished or self-published work by the same editor who created the article. Any merger should be done with care.--Srleffler 20:17, 12 March 2007 (UTC)

It's self-published, so definitely WP:OR. We should merge it here only if/when it gets published. On the other hand, the same material, maybe in less detail, can be found in other sources, so maybe someone wants to write a section based on w what can be found easily in online books, etc. The other article needs to be deleted. Dicklyon 16:53, 14 March 2007 (UTC)
This article is focuses on optical speedup offered by line moiré patterns (i.e. an accelerated fast movement of moiré bands when moving one of the layers). It presents a new simplified set of equations for achieving any desired optical speedup factor with curved line moiré patterns. The article should be further extended to present also rotational movements achieved with circular patterns. Except grid and line moiré patterns, there are also well known Glass patterns comprising random lines or dots, namely random line moiré and random dot moiré patterns. All these superimposition patterns have different behaviours and often require different mathematical approaches. These varieties should be taken into consideration when deciding whether a single article for moiré in general is sufficient or dedicating separate articles for moiré (in general), line moiré, micro-shape moiré (magnification effect of microscopic shapes, sometimes called band moiré), random dot Glass patterns [example], and random line Glass patterns [example] should be considered. Gabrielyan 17:59, 15 March 2007
You say that the article presents a new set of equations. This is precisely the problem. Wikipedia, by policy does not publish anything new. New research results must appear in a reliable (not self-published) publication before they can be presented here. The only references presented at line moiré are your self-published paper on ArXive, and your own websites. This is not sufficient. The best resolution of this would be for you to remove from the article everything that is your own original research until your paper is published in a journal. If that is the entire article, we can delete the article until the research is published. If the article contains some material that has been published, the article could be cut back to that material for now.--Srleffler 18:18, 15 March 2007 (UTC)
At this moment, the article contains only the portion of our research which should be considered as introductory and publicly known material. The purpose of such article was to distinguish at this moment line moiré as an autonomous part of the general phenomenon of moiré patterns (as it should be done also for the cases of random dot patterns, random line patterns, and micro-shape band moiré patterns). I suggest adding corresponding references... Gabrielyan
I agree it's probably publicly known; I've know about it for decades, possibly from some booklets from Edmund Scientific who used to sell moire kits (maybe still do). But since you wrote it, it would be best if you would find and add the references. Referring to your own work here is some combination of WP:COI and WP:OR, so not right. Dicklyon 23:49, 15 March 2007 (UTC)
I see that someone already improved the introduction of the article and made it more clear. I will take care of the references. Gabrielyan 09:41, 16 March 2007 (UTC)
The references are added Gabrielyan 20:16, 19 March 2007 (UTC)
Thanks. Proper referencing is a lot of work, but well worth it. Wikipedia policies aside, the article is much improved by having good references to the literature. By the way, I replaced many of your calls to {{cite book}} with {{cite journal}} or {{cite paper}}. Cite book is only for books. Cite journal is for papers and articles in periodical publications such as scientific journals or magazines. Cite paper is kind of a catch-all template for papers not published in a regular periodical. It's good for unpublished work, ArXive papers, and also for theses and the like.--Srleffler 20:47, 19 March 2007 (UTC)

## Moiré Corps.

I think that this small experimental site I've put together with a friend should be added to the external links

it is meant as an exploratory realm for us (and potentially others) to explore the visual qualities moiré patterns as they relate to art and design.

I also think that "conflict of interest" guidelines don't have to be taken so literally, given the direct and obvious correlation between the content of this wikipedia page and the site I'd like to add. I'm not trying to be an arrogant a... just not used to this.

thanks, would love to see the site up and think others would appreciate it. -ryan 72.195.135.6 08:31, 11 April 2007 (UTC)

No nay-sayers, guess I'll add it up! -ryan 72.195.135.6 19:53, 16 April 2007 (UTC)

I disagree. The guidelines of WP:COI should be taken very seriously. Your job is to convince someone else to add it, since if you add it yourself it will be removed. Dicklyon 22:12, 16 April 2007 (UTC)
Why can't I convince you? do you think the stuff we've done is uninteresting/nontechnical/sophomoric/groundbreaking/all of the above?72.195.135.6 15:20, 18 April 2007 (UTC)

## 0<δp<1

The article says: The step of the first pattern is p, the step of the second is p+δp, with 0<δp<1. What is the meaning of 0<δp<1, since 1 has no dimension? Should it be 0<δp<p? (Nomeingles (talk) 03:16, 6 January 2009 (UTC))

## removal of part of the application in strain testing

I removed the following from the article, because I feel that such practical and detailed description of how it is done is not enceclopedic, in the sense that it tells nothing about moire patterns itself. It is however very good and exact, and I didn't want to remove it without keeping a back reference on the talkpage. I nowikid the subheadings in order to keep the talkpage layout. Martijn Hoekstra 22:35, 3 May 2007 (UTC)
=== Uniaxial traction ===

Let us consider an object with a length of l, and we draw a pattern with a step p; the lines of the pattern are perpendicular to the axis of traction.

When the object is under tension, its length becomes l·(1+ε), where ε is the strain (relative stretch). The step of the pattern becomes p·(1+ε), and thus δp = p·ε.

The spacing between the center of two dark zones is:

${\displaystyle 2d={\frac {p}{\varepsilon }}}$

this spacing allows the determination of the strain. However, the determination of the center of a dark zone is not accurate, because the zone is wide. We can instead count the number N of dark zones: on a length of l, there are

${\displaystyle N={\frac {l\cdot \varepsilon }{p}}}$

darke zones, i.e.

${\displaystyle \varepsilon =N\cdot {\frac {p}{l}}}$

The accuracy of the determination is the difference of strain between the apparition of two dark zones, i.e.

${\displaystyle \Delta \varepsilon ={\frac {p}{l}}}$

=== Shear strain ===

In the case of a pure shear strain, we draw a pattern which lines are perpendicular to the shear forces. The pattern on the deformed object is turned by the shear angle γ compared to the reference object (undeformed object).

For the same reason as for uniaxial traction, we can count the pale zones, as long as

• γ is very small,
• the object is rectangular, and
• the forces are parallel to the sides (the pale lines are then almost parallel to the sides of the object).

When the width of the object (dimension perpendicular to the forces) is l, then the number N of pale lines is:

${\displaystyle N=l/D=l\cdot \gamma /p}$

i.e.

${\displaystyle \gamma =N\cdot {\frac {p}{l}}}$

and the error is

${\displaystyle \Delta \gamma ={\frac {p}{l}}}$

## Descreening?

I'm amazed that not only does this article not mention descreening (a software option for optical scanners), but apparently it isn't mentioned anywhere on Wikipedia at all. Is there some technical reason for it to not be mentioned, or has the term simply never come up and it might as well be included? —Preceding unsigned comment added by 4.254.115.210 (talk) 21:24, 16 October 2007 (UTC)

## Interference

Does anyone else think that the use of the word "interference" is somewhat confusing? Perhaps as mentioned above "superposition" is a better description of the phenomenon, personally I think interference suggests that amplitudes of light waves are interfering, as in diffraction. Clearly Moiree patterns are a geometric optic phenomenon. What does anyone else think?

Yes, this has nothing to do with optical interferences. These are spatial interferences, just a contrast effect. It is not a geometric optic phenomenon neither.

Right on!! Interference connotes wave amplitude and phase differences. These are well treated in all optics texts--which, incidentally, do not discuss the moire phenomenon, even in passing! Moire has nothing to do with wave optics. Moire is completely explained by a careful examination of the light paths from the source through the pattern (eg. screens) to the detectors. There is nothing mysterious about the perceived patterns. They are completely explained by the position of printers ink on the page. Ones subjective impressions from these patterns have nothing to do with physics. Moire may better belong in a discussion of optical illusions. — Preceding unsigned comment added by Orblau (talkcontribs) 04:36, 31 May 2012 (UTC)

Just want to add my (belated) comment that I think I successfully addressed and corrected all the objections to the "interference" section -- including changing the name of the section. The key issue here is what ink does to paper. This is a complex topic which I rendered very simplistically, but hopefully correctly this time. I also amplified the general talk page commentary about interference vis-a-vis Moire. Siw1939 (talk) 15:25, 29 September 2013 (UTC)

## Image files (Specifically within "ROM"s)

Is it worth mentioning that there is a Moiré effect when using an image extractor looking for the correct pattern/position of the images while aligning everything, specifically noticed in an app known as "Tile Molester"(Google it)? —Preceding unsigned comment added by Cm0n3y34 (talkcontribs) 01:57, 11 June 2009 (UTC)

## Another picture candidate

Pretty.

I thought this photo of the World Trade Center buildings would be a good moiré pattern photo to include in the article, especially as a photo of a real thing and not a diagram. This thumbnail's pattern differs from the diamond-shaped moiré in the original, too, showing some effects of downsampling. Anyway, the article is so full of photos already that I'll defer to those who have worked on the images before. Comet Tuttle (talk) 21:43, 5 January 2010 (UTC)

## interesting use of moire patterns

this is very interesting: http://www.demoscene.tv/page.php?id=172&lang=uk&vsmaction=view_prod&id_prod=13916 some reference to related research perhaps? —Preceding unsigned comment added by 213.221.224.21 (talk) 22:56, 27 February 2010 (UTC)

## Gallery

I think the article has too many images at right. A gallery should really be used instead when there are this many images. 02:03, 11 June 2011 (UTC)

## Algortihms

It would be nice to have algorithms for the actual patterns. I.e. formulas to create them independently of the underlying shapes. 04:47, 26 June 2011 (UTC)

## Etymology again

Sorry, but I just read the etymology section and it makes no sense as written, as far as I can see. I don't know the etymology of the word (that's why I was reading it) so I cannot offer to correct it, but I am a linguist and I am pretty sure that what it says doesn't make sense. --A R King (talk) 13:33, 10 April 2014 (UTC)

## Tom Scott video

Tom Scott made a video showing marine navigation beacons and talking about them, could be interesting to add a link to it. The effect is shown clearly at 00:45. --Ihaveacatonmydesk (talk) 21:32, 5 March 2018 (UTC)

edit: the military research he talks about could be useful to add too http://www.dtic.mil/dtic/tr/fulltext/u2/a168108.pdf
Adding a link to the Tom Scott video for people - https://www.youtube.com/watch?v=d99_h30swtM 176.251.175.52 (talk) 08:48, 13 June 2021 (UTC)

The moiré effect is used in shoreside beacons called "Inogon leading marks" or "Inogon lights"... The moiré effect creates arrows that point towards an imaginary line marking the hazard or line of safe passage; as navigators pass over the line, the arrows on the beacon appear to become vertical bands before changing back to arrows pointing in the reverse direction.

The photo of an Inogon light at the start of this section does indeed show a pattern pointing to the right, but there are no arrows in the ordinary sense of the word. Instead, there are several lines converging to the right but not meeting. Where traditional arrow symbols (→, ⇒, ⇨) have just two lines that converge to meet at an angle, joined there by a third line that bisects the angle (the shaft of the arrow), the Inogon light displays multiple lines that do not meet, and there is no shaft. I suggest replacing the sentence I have underlined with

The moiré effect creates a set of lines that converge to the left or the right, suggesting arrowheads (<, >) pointing towards an imaginary line marking the hazard or line of safe passage. As navigators pass over the line, the "arrowheads" on the beacon appear to become vertical bands before changing back to arrowheads, now pointing in the reverse direction.

--Thnidu (talk) 00:30, 4 November 2019 (UTC)

Perhaps they could be described as "chevrons pointing towards..." Jruderman (talk) 00:16, 3 May 2020 (UTC)

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