Stefan,
I used a DVX100A for 9 months and with the anamorphic adapter for 3 months and NEVER experimented any bad artifacts like the ones i see on Clive's grab frames, NEVER.
I have used "thick" and "mid" and "thin" for broadcast applications without any problem. no joke.
"thin" v detail setting has the best resolution and i use it for broadcast applications without any problem.
So this IS NOT normal for a good DV camcorder.


So i think that there are only 2 possibilities in this case (XL2 grabs):

1-Or the XL2 have a real big moire problem.
2-Or the upsampling algorithm (converting 720X576 to 1024X576) is very bad.

i just can't imagine that Canon would release a camera with that kind of problem so i think it has to do with the upsampling algorithm that Clive used to post those grabs.

...but if it comes from the camera, then it is not funny at all...

that's why i want to see full quality JPEGs in native 720X576 res.

Antoine
I would have to agree with you that I have never seen a patterning problem like the one that Clive has posted, however, Higher res footage ie adapter and thin settings do produce some strange flickering when shooting certain patterns, ie. bricks fences etc. I have never seen it look like it does as the grab is posted, however, like Clive said, there is a filter applied to it and that cannot truthfully portray the optical pheonomenon that is seen through an interlaced televion. I hope that this really is the case, as I doubt that canon would release a camera that looked that bad on interlaced television.

Antoine,

I don't think it's anything to do with the the upsampling algorithm. I have no problems in exporting 720 x 576 to 1024 x 576 - this is normal to get 16:9 export still from anamorphically squeezed PAL - it should not look bad.

The reason this still looks so bad is given by Clive himself - he captured it into Media 100 via composite analogue - when he should have captured it as native DV.

Best regards,
John.

Clive, why haven't you posted an image captured in native DV as requested? It certainly would help put some issues to rest.

Jay

Well I guess the moire problem is not connected nor with upsampling of the image into 1024x748 nor with any TV or PAL issue.

I bet it has something to do with deinterlacing method. As interlaced material doesn't have a moire, and "progressive" has I would turn the spot on the fact that there's something wrong in the way in which the camera does "progressive" scan.

Look at the lamp in http://www.showreel.org/XL2/morray.html
The interlaced one is smooth, but the "progressive" one is jerky. The jerkeness is very similar to the look of interlaced footage treated with deinterlacing algorithm which IS NOT the same as true progressive scan of the image.

My bet is XL2 DOES NOT utilize the true progressive scan (as in DVX100), but is rather something like "frame mode" in previous models.

Can I refer you to a frame grab I made in Progressive scan and with Cinegamma?

http://www.simplydv.com/Reviews/canon_xl2_popups/xl2_popup10.html

If there was to be a problem with moire, I would have thought it would show up on the slates on the roof.

However, I have heard from Canon that the beta version of the XL2 which people were playing with was probably only at 85% of the final picture quality that we can expect in the release models ;-)

Robin
SimplyDv.com

guys,

...captured via analog with media 100...OK, didn't know...
...and yes, i too believe that the deinterlacing method may produce such results....

"My bet is XL2 DOES NOT utilize the true progressive scan (as in DVX100), but is rather something like "frame mode" in previous models."

I think there is little doubt that the XL2 uses true progressive scan - look at the resolution of Robin's shots.

Again it has nothing to do with deinterlacing either - the break up on the lampost and sign is diagonal. It is clear to my eyes that it is simply a low quality composite analogue capture, and that is confirmed by what Clive has said.

It is exactly the sort of artifacts I see on my monitor when the picture is turned to composite rather than component or s-video.

Best regards,
John.

<<<If there was to be a problem with moire, I would have thought it would show up on the slates on the roof.

The funny thing about moire is that it only shows up a certain pattern frequency/ chip resolution frequencies..lets call it the M-factor...The way to test it with a video camera is to find a suspect pattern and zoom through a range of focal lengths....depending on the pattern, a moire pattern will appear, change, disappear, and possible reappear....the greater problem, is, as clive found...moires will occur at different times depending on the output device...the viewfinder, monitor, or computer screen...because they all have different resolutions (ie screen frequencies).

The thing to remember is that moire is a natural expectation given this type of image capture. The fact that the xl2 resolves at a slightly higher level make it more likely to "see" the offending patterns, and thus will perhaps, in some situations, create a moire pattern in situations where the lower resolution xl1s wouldn't have (and transversly, not produce moire in situations where the xl1s would have). The second thing to remember is that the problem is much worse at the output end, as monitor resolution is typically quite a bit lower than the aquisition resolution....as clive's image shows us....we see it on the monitor version(I still don't know how he created this), but not on the actual image.

Barry

John, Antione, and all who are concerned with the method of capture. Read Clives comments and you will find that the method of capture is irrelevant because Clive wished to show an "Impression" of what he saw in the camera, and on the video monitor. And all other faults, problem areas are to be ignored because they ARE, as Clive admits, a product of the capture. This does not present us with any greater an oportunity to assess the footage because visual "impressions" or representations are not really telling us much. However, understanding this might help us to stop chasing our own tails.

"However, understanding this might help us to stop chasing our own tails."

I think this is unfair Bill.

Firstly if there is a serious moire problem with the XL2 then the only result that matters is the full quality end one - i.e. native DV capture.

Secondly if we are talking about a problem with the viewfinder LCD and composite out to a monitor whilst shooting, then let's be clear about that.

I often shoot on the XL1s with an external monitor attatched to the composite out of the MA200, and this kind of thing is common, plus things like moire do become accentuated. It's not ideal but I have become accustomed to being pleasantly surprised when I finally capture the footage into the NLE.

Best regards,
John.

John I think you misunderstand my intentions. I agree, there is a need for
an actual, true "this is exactly what was recorded" type of thing, and not what Clive has admitted to as being an interpretation of what he witnessed. An "interpretation" that could just as well be a pen and ink sketch as far as I'm concerned. And yes, you are correct, a native DV capture would do the trick- or at least it should be enough for a fair(er) analysis. But, taking this into account I have no idea why anyone would bother with this CREATED "representation" no matter how it was captured. On another note the gull looks superb and apart from moire testing, the smoothness of the background is very telling, not to mention other factors like the detail and highlight rendering etc. Clive is in a position that demands a more accurate approach than simply trying to describe what he feels is an issue. We need head to head comparisons and other fair methods of assessment.
All the best.

This thread is starting to chase it's own tail. If we read Clive's last post, he says he is leaving the discussion.

"This thread is starting to chase it's own tail. If we read Clive's last post, he says he is leaving the discussion."

Sorry Jeff, perhaps it is over until he responds further, but I thought it was quite interesting and it seemed to me that Clive left without answering the key question.

All he has to do is provide a native DV capture of the same image - then we can properly judge if the XL2 has a more than unusual moire problem.

Best regards,
John.

yep, easy...

just post a native DV grab frame...

Hi guys.

Just thought you'd like to know that I've finished my test of the XL2 for Showreel and I've managed to figure out how to eliminate the moire patterning that was evident when shooting in 25P mode. The magazine is at the printers today and we'll be out next week. As to my knowledge we are the first magazine to complete a full test of the camera, my publisher has agreed to send to article in pdf form to international subscribers at the
same time as it's received by UK subscribers, as international subscribers usually receive it a week or so later.

If you are interested, please email denise@showreel.org."

Clive--

Why haven't you posted the native DV capture as so many of us have requested? Sure would like to see it!

Thanks.

Jay

Sorry. Been busy lately.

Will post in a minute.

Clive

Thanks for your information and feedback regarding the xl2. What was your solution in eliminating the moire patterning in the 25p mode?

Barry

What happened to this section ? no anwers....if clive left...somebody who has xl2....doesn't they observed anything about moire pattern.? Or no one is going to answer . This dv community is becoming fireworks...after releasing canon xl2.....
we fight about 8 bit .....found a solution lately but its 12 bit.
now with this image pattern issues.......no solution or hiding...may be canon guys might be observing this forum carefully.. might be coming with an answer..well....its hot in jamaica...everybody is hot for canon xl2....... well thanx buddies and folks.........

vamshi

varnshi

glad it's hot in jamaica...its nice, but not too hot here in california...

repeat after me....there is no moire problem...there is no moire problem...there never was a moire problem.....


hope this helps.

Barry

Sorry barry................i cant follow you in your band wagon....

keep cool my xl2 is coming soon.....if i observe....this pattern/that pattern ....you are going to buy my camera....?

<<...you are going to buy my camera....?>>

Varnshi

sorry...got my own on the way...no money back guarantees here at dvinfo.net.

Look...if you read through the thread you'll see a pretty good consensus amongst the more experienced voices that moire is a fact of life with all video cameras, and it has always been this way ....If you should stumble upon some with your new xl2 (which you probably will if you look hard enough) then you are in good company...(go grab two pieces of window screen and overlap them...see if you can do it without some secondary pattern --moire-- being formed.) This is exactly what you are doing with a video camera when you photograph a brick wall, or a set of venetian blinds...or a window screen. Monitors, tv's etc are even more likely to introduce moire (in fact as clive's stills show...they will show moires even when there isn't one in the camera image).

IF, and this is definitely an if.....the xl2 exhibits a higher degree of moire than another camera then it is simply because the xl2 is resolving at a higher, better, level...which is what we all keep saying that we want.... DVX users have had to deal with similar issues relative to line twitter ( a form of moire) as the resolution of the camera in progressive mode is simply higher that it needs to be for SD monitors (but play it back on a HD set and you'll watch the patterning go away and swear the image is HD).

Varnshi...if you get moire in an image, there are several strategies for dealing with it...and they are detailed earlier in this thread. Its your job as a videographer to understand not only how good your medium is, but also its shortcomings and limits, and to take the appropriate steps to avoid those shortcomings.

I think I'm out of hot air for awhile.

Cheers

Barry

Doesn't sound like hot air to me -- sounds like an experienced operator who definitely knows what he's talking about. Thanks as always Barry,

<<IF, and this is definitely an if.....the xl2 exhibits a higher degree of moire than another camera then it is simply because the xl2 is resolving at a higher, better, level...which is what we all keep saying that we want.... DVX users have had to deal with similar issues relative to line twitter ( a form of moire) as the resolution of the camera in progressive mode is simply higher that it needs to be for SD monitors (but play it back on a HD set and you'll watch the patterning go away and swear the image is HD).
>>

This is an interesting point Barry. I've actually never viewed any of our work directly on an HD monitor because...well, I've never shot in HD. Are you saying that, in theory, Xl2 footage will look similar to HD on an HD monitor?

Similar, no...if you put a good HD source next to DVX footage the difference is clear. But you'd be surprised how good DVX progressive footage looks on an HD set. Especially in limited movement, relative close-up type shots...like interviews. It certainly looks as good as the compressed HD streams that typically come over satellite and cable. (lots of movement in high contrast situations will typically start to show some aliasing).

The point being that the DVX's 480p ( and now the xl2's) are somewhat overkill for SD monitors, and there can be a price for that extra resolution. This is why both of these camera's have detail settings that essentially lower the resolution when you get in trouble.

On a side note (actually, the original note)...I just did a camera test with my DVX on a home made moire chart...fun stuff...lots of rainbows...shimmering all over the place...guess we better recall all those panny's. Funny thing happened...I noticed that when I got a certain distance from the chart...I started SEEING moires with my eyes (no camera) --guess this is what the Op-artists were doing... my eyes must be defective too....oh I am tired....see y'all.

Barry

Howdy from Texas,

"When new lines meet your eye
from two screens as they ply,
that's a-moire."

Where strange colors now shine,
they weren't there the last time,
that's a-moire."

(apologies to Dino)

I think you need to apologise to us all for that one Chris! ;)

Aaron

Love it. Can I use it, chris?

I went home last night, and I was trying to explain this moire thing to my girlfriend--she was watching the olympics- 400m hurdles I think- and I looked up at the screen as it was pulsating like electro shock therapy from all the lane lines on the track surface...

I said, "its like that honey"...

she just nodded in that knowing way.......

Barry

hi barry...

nice convincing factors, may be your girlfriend listerns...but no body is ready to nod like a goat....


Well Chris...

Nice poetry.....I think you should publish in the book
After all you are head to all of us...This is kiddish man.

I went to some other sites they were real ,saying that chris is the moire pattern for canon....i never believed....well....this forum is becoming foolish.....I think better to find some other forum...where i can get professional strategies....... I am saying good bye to this forum....

well wish you a good luck ,for every one....


bye bye....


vamshi

Varnshi

your probably gone...so you won't hear this.......feel free to go after me ...but Chris doesn't deserve your comment. There isn't a better person in the web world, and as much as this site has always been a clearing house for Canon oriented information and discussion, I've probably heard chris recommend other cameras from other manufacturers a dozen times on these boards. He's publicly lusted over the 12 bit dsp in the panasonic DVX100, and has offered his web bandwidth to discussions on virtually every topic and manufacturer in this industry. Yes, he is close to canon, and that's why we get such great, detailed information on this site...rather than the rumours, speculation and crap on so many others.

Barry

Vamshi (if you are still here)

I am baffled by your attitude. Barry has provided some excellent information in this thread, which has been very educative for me and probably many others.

As for your attack on Chris and this website, I think it is completely unwarranted. Show me one instance where he has promoted Canon cameras. In fact, you will find a lot of speculative (and apparently largely unwarranted) criticism of the XL2 on this forum. None of this has been censored. Chris will always challenge factual errors, but not opinion. Would you prefer it some other way?

Good luck in finding a better forum for discussion on DV - if you find one, let me know because I haven't been able to. I do, however, suspect that you may find some better poetry sites.

Best wishes
Duncan

Alright Barry /Duncan.

Good Toast for Chris.. I think you are the good friends for him. I dont even mean to hurt anybody.. This is a forum. ..Everybody comes up with his problems... 2-3instances i observed chris.....answering roughly.. And in dealing with an image problem ..... can you guys answer for this thing...

"When new lines meet your eye
from two screens as they ply,
that's a-moire."

Where strange colors now shine,
they weren't there the last time,
that's a-moire."

its clearly an insult to clive.

I said its nice poetry. Alright, he never comeup with an answer, he took the help of you guys...to support him...this is absolute reality.

Regarding 3 instances... this issue about image problem
the others are regarding the mic problem.. he has given a rough -rough answer.....So also why he never comeup with an answer...why he is not watching this forum......

I dont mean to raise my hand on anyothers....
Weather he supports canon or not is his issue....I also supports canon...,but comparision is my juncture.

Any way guys....cool.......

Gents, if this helps at all:

Even when you are shooting film that will ultimately be transferred to video, you have to watch out for potential moire. You don't get the luxury of seeing it on the monitor and deciding what to do with it, you just have to be knowledgeable enough to say "I think we might have a problem with that pinstripe tie" or "the screen in that window may moire down the road". Recent telecine technology has eliminated a lot of this but there are still no-no's out there; as Barry pointed out, you can even get your eyes to moire under the worst of circumstances!

Obviously if one camera exhibits more problems than another, that's reason for concern. Until we actually see side-by-side examples of, say, the DVX100a and the XL2 pointed at the same environment where the problem manifests in one camera vs another (and the detail and other relevant settings are as similar as possible), then I say it's pointless to debate. With all due respect to the intrepids who are posting their initial tests, it seems to be stirring the pot more than anything else. I'm looking forward to a thorough set of tests under multiple shooting situations, from charts to real-life high-contrast scenes to lowlight scenes, with both cameras. I'd be happy to do them myself, if Canon sent me a camera.

Oooh... Nice cast there Charles, Hope you get bite!

I'm betting by this time next week Charles. I'm looking forward to a controlled studio test of Xl2 with different lenses and with the P&S...I have the XL1s for comparison as well.

Sorry to bring this up, but I just read this thread. It's very strange to me that no one here recognized this right away by looking at the two images.

It's not the lens. It's not photoshop resizing. It's not the CCD. It's not related to anything at all, except deinterlacing.

Take the better of the two images, go to photoshop, go to Filters > Video > Deinterlace (default settings). You'll get the same moire patterns as with the other image.

The problem is that the second "progressive" image got deinterlaced somehow (progressive should never be deinterlaced by definition) because of inappropriate settings within the software/camera etc.

As for this effect being visible in the viewfinder -- could be camera settings, or perhaps the camera doesn't have a progressive path to the viewfinder. The output would be progressive regardless, and should be free of any artifacts as such.

I don't personally use these cameras, so I can't comment on any specific options they may have for this. But this is a very simple problem nonetheless.

Edit:
About the viewfinder moire -- another big factor would be simple downscaling of a 960 x 480 image > viewfinder pixel count. That would just result in simple aliasing then, which in turn would create moire patterns on fine lines, grids etc. The solution then would be to get a good CRT viewfinder.

Nick

Clive says the artifacts are present on a monitor when the video is played back. This would eliminate PS and de-interlacing as as source of the artifacts.

Sorry, but it's most certainly deinterlacing. There is no doubt.

There is no other way a progressive image would lose half of it's vertical resolution in this exact manner. Look at anything diagonal in the picture. You can see very obvious staircasing and pixelation -- that's a result of very basic deinterlacing.

Monitor - what kind of monitor? If it's a video monitor then it will most likely be interlaced, (unless it specifically supports progressive) which could easily create moire when progressive footage is played back on it. You have to use progressive video monitors to play progressive footage. If your final output is intended to be interlaced, then you should shoot in interlaced mode to begin with...

If progressive footage shows moire effects on a computer monitor, then I would say it's most likely an automatic deinterlace setting that was left on somewhere. The software we use here is different, but it allows specifying whether the source has fields or not, and the program will deinterlace the video automatically while you edit it, but keep it interlaced on export. I'm guessing basic video editing programs assume DV footage to be interlaced by default (which makes sense).

To be honest, the reason could be anything. But I can say from my very substantial experience with doing video transfers that the moire artifacts that Clive showed are definitely as a result of deinterlacing. That's the one statement behind which I stand 100%. The rest is in the details...

For further proof, please try what I suggested. Save the better progressive image provided by Clive (without artifacts) and open it with photoshop and run Filter > Video > Deinterlace. You'll see that it's totally identical to the image with moire, down to the finest details.

I knew what the problem was the second I saw the bad image, I've been deinterlacing videos for a long time. Sorry if I sound too pushy, but this is an area that I have far too much experience in. :)

Nick, I'm not really disagreeing, but Clive has quit posting again (I think he wants us all to take out a subscription) and without access to the native DV files it is impossible to tell the cause with 100% certainty. I agree with what your saying and I was headed to the same conclusion in my first post. However, his insistence on seeing it on the monitor leaves many gaps in trying to determine it's actual cause.

I got bored and tried the photoshop test, and it looks exactly like moired image when you apply the deinterlace filter. I don't know if this means anything, and I'm not trying to fuel anything, but it's just to let y'all know.

<<<-- Originally posted by Nick James : Sorry, but it's most certainly deinterlacing. There is no doubt.


Monitor - what kind of monitor? If it's a video monitor then it will most likely be interlaced, (unless it specifically supports progressive) which could easily create moire when progressive footage is played back on it. You have to use progressive video monitors to play progressive footage. If your final output is intended to be interlaced, then you should shoot in interlaced mode to begin with...

:) -->>>

Nick, I would have to dissagree with you on this one. While progressive footage will look best on progressive scan TV's, progressive footage works great on interlaced television as well. In fact, you should not be limited in any wayt that you shoot, because progressive footage has a much different asthetic than interlaced footage. IF everything that was shown on interlaced televisions was interlaced then you could say bye bye to your DVD collection, lots of nightime drama shows and sitcoms witch are shot on film or progressive HD. Progressive footage displays fine on interlaced TV's and even interlaced footage can display moire problems like that described by Clive.

The fact that the moire is visible on a monitor, but not in the image is no great mystery. I did a test with my DVX the other night, shooting a test chart designed to produce a moire, or rather lots of them. Viewing the image through the LCD produced wild, crazy moires, while viewing through an NTSC monitor produced a very strong set of patterns as well. When I imported the footage I was not surprised to see that the moires had almost disappeared..still evident but much less noticeable...but more interesting was this....the moires on the actual image were different moires than the ones appearing on both monitors during filming. This make sense because the varying resolutions of said monitors are going to interact with the source pattern each in a different manner.

The pattern of the bricks alone in clives footage (as charles alluded to in his post about shooting film) would (or at least could) cause moires on a monitor without the actual recorded image having any.

Now regarding the interlace thing...we're really talking about the same process except we're creating it in the image instead of viewing it on a monitor. We have an image that has a pattern with no noticeable moire (there is actually a very slight one, but it is almost invisible)..photoshop's deinterlace filter does little more than halve the vertical resolution by either blending alternating lines or, throwing away one set and doubling the other...so essentially it has lowered the "output" resolution overlaying the pattern...producing a moire...you can produce almost the same result by resizing the image to 50% using nearest neighbor interpolation (bicubic..which is photoshops default is designed to avoid such patterning). So in a nutshell...deinterlacing in itself has nothing to do with this except in that it is lowering the vertical resolution of the image...

(one more thing...try the deinterlace trick and then toggle between the before and after zoomed way in...you'll start to see the slight moire in the actual image that I mentioned above..and you'll notice that the deinterlaced one is opposite in value from barely perceptible one in the image.

Barry

I tend to agree with Jeff. He's being more subtle than I would. As this thread has progressed and as I've watched what Clive has posted, or more importantly hasn't posted, I've been led to think he has an agenda. I can't say what that agenda is, because I don't know. It reads to me like we're being baited, and in my mind, this whole thing is suspicious. Frankly, I don't appreciate such tactics.

Jay

Received my XL2 yesterday, had a chance to play with it tonight. I hate to be negative, because I want this camera to be awesome more than anyone else. Pulled the pieces from the box, assembled it, threw in a tape, and started recording. The only option i changed ..was the frame rate ..i set it to 24p ...recorded 3 minutes of footage around the living room. ...hooked the video cables to the tv (standard 4:3 tv) ...hit play ....and instantly noticed very significant and distracting "moire" or "artifacting". ...I'm not an expert, so I cant say whether it's moire or artifacting or both. The main objects I noticed it on were the wooden shutters in the windows, and the frames of pictures, hanging on the wall. .....I started playing around a little bit ..and just kind of looked at the camera, then i switched it back to manual mode, while still hooked up to the TV ...I left the camera on top of the tv aiming at the walls with the shuttered windows ......And I noticed "flickering" around the edges of the shutters.?? Note that the camera wasnt moving at all. .

So ...I guess I'm not sure what to do.

Also ...has anyone noticed in 16:9 mode ...when looking through the VF ....do you notice the letterboxed area on top ..kind of flickering? ...

Some positive comments:

This puppy is built pretty solidly. I mean, it feels rock solid. Very impressed with that. I owned the DVX100 ...pulled it from the box, was disappointed with the build. It felt cheap. So I sent it back the next day.

The xl2 ...just looks beautiful. To me, the looks of the camera alone are worth $2,000.

The little bit of recording I did around the house, I was very impressed with the color reproduction.

Was also very impressed with the low noise in "dark" situations.


Keep in mind, I've only recorded about 10 minutes worth of footage. I'm worried about the moire problem, but I am so impressed with the camera, overall, that I'm going to keep it, ..and hope that I can "learn" how to minimize the appearence of the moire ....assuming that the moire problem isnt a defect, but rather just the "nature of higher definition cameras" as stated on this forum.


j.

Can you upload or send a dv sample to show the moire effect???


regards
Daniel

You know, I see moire all the time when watching TV on a 32" set, especially the typical interviews with some guy who wears a fine stripped shirt, and this is usually shot using broadcast camcorders with broadcast 2/3" lenses, so I'm tempted to ask, what else is new?

Did people expect this problem (which is more IMO a weakness of our interlaced monitor systems in general than the cameras used to shoot for them) to magically disappear with the XL2?

I mean, I'm no expert, but if you shoot progressive, edit progressive and then see the footage on an interlaced monitor and it has moire visible, wouldn't it point to the monitor being the problem instead of the camcorder?

Because as far as I know, a true progressive scanned image is supposed to be like a digital photo, without interlaced lines of resolution, so this shouldn't influence the output. What might influence it (again, I would think) is the level of sharpness in the image, a sharper image being more inclined to show moire than a softer one, because the latter kinds of smooths any fine lines in the details (kind of like anti-aliasing on a computer).

So if this is correct (and please do tell if I'm wrong), the best solution would be to shoot with the XL2 with details set at "high" and then, if you see problems on an interlaced monitor, just apply some kind of anti-aliasing filter just on the scene(s) that causes problems in post-production. If you plan on transfering to film, this shouldn't be a concern at all I would assume.

Anyone how cared to notice would have seen the same thing on NBC's Olympic broadcast for a good example. Take the track sports and look at the white painted lines on the tracks....moire. Fortunatley only video geeks would be looking at the white line patterns instead of the Olympic action.

yep,

if you watch carefully a Hoolywood DVD (film to very very high quality CCDs transfert), then you'll see tons of these. It is normal when you watch high res progressive footage on an interlaced TV monitor.

A great book on Communications, "How Real is Real" has a story about perception/reality in it. Apparently, during the late fifties, while the atomic testing was going on in the desert... a story went round that the fallout was drifting onto windshields, and causing pitting. People started to look at their windshields, and sure enough, there was significant pitting going on. Enough for the government to do a study.

What they found out was that windshields ALL OVER the US were pitted. What had taken place was not an increase in pitted windshields, but an increase in LOOKING AT WINDSHIELDS. What people had been looking THROUGH all of their life, they were now looking AT.

Funny how that works.