what is"moire" and how do you get rid of it.

what is"moire"The following image is nothing more than concentric circles. But depending on your display, you will begin to see some other patterns appearing near the center.

A "moire pattern" is the unique pattern that is created when you merge two screenlike objects together.

In this case, one screenlike pattern is the concentric circle design and the other screenlike pattern is the layout of the pixels on your display. Where those two screenlike patterns begin to 'interfere' with one another, a moire pattern emerges.

In video displays, moire patterns are cause when certain video images interfere with the tiny pattern of pixels on your display.

Moire distortion is also an immediate and unavoidable artifact created when 'keystone' correction is added.

http://www.coolopticalillusions.com/eye-tricks/optic-pictures/moire_circle.gif

Having just run through a calibration disc the other day, moire is a pattern of colors produced artificially on the display by fine lines on the image. The point of the segment was if you see colors in the midst of the lines, you should look for a better signal path. Example given was composite signal will produce it but S-Video or better (component or HDMI) will not.

Try this link for more confusion.
http://en.wikipedia.org/wiki/Moir%C3%A9_pattern


TerryB

Having just run through a calibration disc the other day, moire is a pattern of colors produced artificially on the display by fine lines on the image. The point of the segment was if you see colors in the midst of the lines, you should look for a better signal path. Example given was composite signal will produce it but S-Video or better (component or HDMI) will not.

Try this link for more confusion.
http://en.wikipedia.org/wiki/Moir%C3%A9_pattern


TerryB
The effect you are describing is called "false color," not moire. It is sometimes incorrectly referred to as moire. Moire can happen even on black-and-white TVs.

The wikipedia link is surprisingly accurate (for wikipedia...) I'm not sure why you find it confusing. The post above is a good demonstration, although I think the interference of circular patterns has an additional mechanism working in it.

http://www.keohi.com/keohihdtv/learnabout/definitions/moire.html

http://www.keohi.com/keohihdtv/learnabout/definitions/moire.html
thanks. that means we have to tell the onair people to quit wearing striped ties and such.

thanks. that means we have to tell the onair people to quit wearing striped ties and such.
If you're talking about "false color," they've known not to where such clothes since the '50s. Johnny Carson and Lindsey Nelson were famous for their "rainbow" jackets. The problem is, most people working in TV these days don't know this (or who Johnny and Lindsey are.)

The good news is that HDTV doesn't have false color unless you are watching a downconverted NTSC output. Moire (as properly referenced) could still exist, especially in computer graphics operations where the images aren't properly filtered during processing.

Here's the classic test pattern.

Composite:

http://www.w6rz.net/mctfoff.png

After a 3D comb filter:

http://www.w6rz.net/mctfon.png

Ron

That comb filter isn't that good. It just took away the luma information where the false color was. Unless it is an artifact of capture and posting, it seems more like a 2-D filter (but why split hairs...)

But note that there is still some moire (at least on my display) even after filtering.

The top picture looks like 2D decoded composite and the lower picture is indeed 3D decoded but shows high frequency loss on diagonals. A 2D decoder will fail on high frequency diagonal luma picture components. It can not tell the difference between subcarrier which is 180 degrees out of phase from one line to the next and fine luminance detail that lies near 45 degrees which will also be 180 degrees out of phase from one line to the next. A 3D decoder should be able to perfectly decode parts of the picture that are the same from frame to frame (monochrome frames) because the luminance information will be the same from frame to frame but the chroma will be 180 degrees out of phase.

The top picture looks like 2D decoded composite and the lower picture is indeed 3D decoded but shows high frequency loss on diagonals. A 2D decoder will fail on high frequency diagonal luma picture components. It can not tell the difference between subcarrier which is 180 degrees out of phase from one line to the next and fine luminance detail that lies near 45 degrees which will also be 180 degrees out of phase from one line to the next. A 3D decoder should be able to perfectly decode parts of the picture that are the same from frame to frame (monochrome frames) because the luminance information will be the same from frame to frame but the chroma will be 180 degrees out of phase.
the question that i have is why does it only happen when they wear ties with patterns and checkerboard and the tv seems like it can't decode properly.

the question that i have is why does it only happen when they wear ties with patterns and checkerboard and the tv seems like it can't decode properly.

You can take two window screens and with a slight rotation of one generate the pattern. A rectangular grid on top of another can generate. In a video raster there is a grid of emitters, the reflected light from the clothing pattern is another grid.

Even though people have known that it can happen, tv personalities still go on the air with clothes that can do it. Weather casters have learned not to wear green clothes though.

the question that i have is why does it only happen when they wear ties with patterns and checkerboard and the tv seems like it can't decode properly.
In a "composite" color system, color information is added to the picture using a subcarrier that is within the bandwidth of the video signal. When repetitive black-and-white patterns in the picture coincidentally occur at a frequency that matches the color subcarrier, the color decoder in the TV will be confused and think that it is part of the color subcarrier signal. It will usually result in a splotch of rainbow colors that really aren't there. That is why it is called "false color."

You can take two window screens and with a slight rotation of one generate the pattern. A rectangular grid on top of another can generate. In a video raster there is a grid of emitters, the reflected light from the clothing pattern is another grid.

You have correctly described moire, but you've confused me with the "grid of emitters." The sampling "grid" in the TV camera and checkerboard pattern in the clothing combine to cause moire. The color decoder in the TV set is the device that creates the false color, regardless of how the light is emitted from the display.

You have correctly described moire, but you've confused me with the "grid of emitters." The sampling "grid" in the TV camera and checkerboard pattern in the clothing combine to cause moire. The color decoder in the TV set is the device that creates the false color, regardless of how the light is emitted from the display.
i guess what you're telling me is that it isn't the tv's fault then.

i guess what you're telling me is that it isn't the tv's fault then.
No, the false color "rainbows" are the TV's fault (if they're getting a composite signal.) If the TV is getting a digital signal, the rainbows got "recorded in" somewhere upstream.

Moire can be created at lots of places in the process.

You have correctly described moire, but you've confused me with the "grid of emitters." The sampling "grid" in the TV camera and checkerboard pattern in the clothing combine to cause moire.


i had a grid of sensors or emitters as supplying one grid. then i edited and it didn't get put back in reply.

Agreed, that covers both ends of the process.

No, the false color "rainbows" are the TV's fault (if they're getting a composite signal.) If the TV is getting a digital signal, the rainbows got "recorded in" somewhere upstream.

Moire can be created at lots of places in the process.
i'm kind of stumped then. i was on an hd feed with a lg3510 with a dvi output. what gives?

i was on an hd feed with a lg3510What do you mean "HD feed"?? What are the resolutions and what gear are you referring to?