Motion blur, judder, etc.

DevilsFan · 07-09-2009, 05:49 PM

This is probably a FAQ but I am really confused about the difference between motion blur and judder. Or is there a difference? I've heard that plasmas do not have a problem with motion blur but like LCDs they may have a problem with judder. If I understand judder correctly, it has to do with the difference between frame rate and display refresh rate. Is this a problem inherent in displaying film on digital displays?

So what is motion blur if it is not related to judder? What causes it and why are LCDs more susceptible to motion blur than plasmas? Also, do 120Hz and 240Hz displays help address the problems with judder, motion blur, or both?

Really confused.

jam269 · 07-09-2009, 06:08 PM

Check this out:

http://reviews.cnet.com/4520-6449_7-6792632-1.html

Specifically, paragraph entired "Motion blur is a fuzzy concept."

DevilsFan · 07-09-2009, 06:14 PM

Quote:

Originally Posted by jam269

Check this out:

http://reviews.cnet.com/4520-6449_7-6792632-1.html

Specifically, paragraph entired "Motion blur is a fuzzy concept."

He says motion blur and judder are not the same (which is what I thought) but he doesn't elaborate on what motion blur is, how it is different than judder, or what causes it.

DevilsFan · 07-09-2009, 06:18 PM

OK, so I am sitting in front of a LCD monitor attached to my computer. If I click on the title bar of a window and drag it rapidly across the screen, the contents of that window appear blurred. I assume this is motion blur, correct? It certainly has nothing to do with frame rates or 24p so it's not judder. Is this condition a result of the pixel response time in an LCD?

jam269 · 07-09-2009, 06:27 PM

Judder:
In Short: Judder is the result of Film, that is shot in 24 fps (frames per second), but is displayed in a frame rate that is not even multiples of 24 (like 30 or 60).

In Not so short: http://www.hometheaterhifi.com/volum...e-10-2000.html (See the section entitled "Re-Interleaving 24fps Film")

Motion Blur:
In Short: TV can't keep up with the fast moving images. The motion is blurred.

In Not so short: http://en.wikipedia.org/wiki/Motion_blur

DevilsFan · 07-10-2009, 11:06 AM

Quote:

Originally Posted by jam269

Judder:
In Short: Judder is the result of Film, that is shot in 24 fps (frames per second), but is displayed in a frame rate that is not even multiples of 24 (like 30 or 60).

In Not so short: http://www.hometheaterhifi.com/volum...e-10-2000.html (See the section entitled "Re-Interleaving 24fps Film")

Motion Blur:
In Short: TV can't keep up with the fast moving images. The motion is blurred.

In Not so short: http://en.wikipedia.org/wiki/Motion_blur

Knowing a little bit about photography, I understand about blur due to slow shutter speeds. But this can't be the problem with LCDs, because plasmas would have the same problem if the issue was the source video. Motion blur in LCDs must be related to some other problem that is not inherent in plasmas. What is it?

Loves2Watch · 07-10-2009, 11:19 AM

Quote:

Originally Posted by DevilsFan

Knowing a little bit about photography, I understand about blur due to slow shutter speeds. But this can't be the problem with LCDs, because plasmas would have the same problem if the issue was the source video. Motion blur in LCDs must be related to some other problem that is not inherent in plasmas. What is it?

Refresh rate the LCD crystals can't keep up with (refresh quickly enough) the fast moving images.

ckone180 · 07-10-2009, 11:36 AM

Quote:

Originally Posted by Loves2Watch

Refresh rate the LCD crystals can't keep up with (refresh quickly enough) the fast moving images.

Which would be why LCDs are marketed with 120 or 240 hz, and now some plasmas marketed with 480 hz. Kind of silly IMHO.

sartor · 07-10-2009, 11:49 AM

I occasionally have a 'Judder' problem when viewing a DVD on my Toshiba DR560 DVD Recorder. My solution? ->> Just pop the disk into my Phillips 5982 DVD player, and No Judder! The Phillips seems superior at playing a wide variety if disks(including DIVX/.AVI etc), and also seems to totally eliminate judder for me. I have a Sharp 120HZ Lcd HDTV. Both DVD players connected with HDMI cables.

**PFC5** · 07-10-2009, 12:43 PM

Quote:

Originally Posted by DevilsFan

Knowing a little bit about photography, I understand about blur due to slow shutter speeds. But this can't be the problem with LCDs, because plasmas would have the same problem if the issue was the source video. Motion blur in LCDs must be related to some other problem that is not inherent in plasmas. What is it?

This is due to the limited response time with current LCD technology requiring more time to retwist the crystals to filter the correct colors that cannot keep up with fast motion and is WHY you have the motion blur. The reason it is not an issue with plasmas (or CRTs for that matter) is because they have response times about 1000 times faster, but this is separate from refresh rates which are how many times the screen refreshes.

Quote:

Originally Posted by Loves2Watch

Refresh rate the LCD crystals can't keep up with (refresh quickly enough) the fast moving images.

I am sure you mean response time right?

Quote:

Originally Posted by ckone180

Which would be why LCDs are marketed with 120 or 240 hz, and now some plasmas marketed with 480 hz. Kind of silly IMHO.

As explained above by me, refresh rates and response times are two different things and mostly handle different issues. Increasing the refresh rate on LCDs does help in the perseption of motion blur, but until they can increase the speed in which LCD crystals can be twisted (response time) they cannot eliminate motion blur. Plasma, like CRTs do not suffer this issue.

Higher refresh rates can help with judder though if done correctly (repeating the same full frame an even multiple of 24Fps film), or done poorly with interpolation of those frames which is when you get the "Soap Opera Effect".

Plasma mfg have been touting the subdrive refrech rate as a marketing way to combat the LCD 120Hz or now 240Hz refresh rate marketing. Neither fully resolve issues, but the recent 600Hz subpixel refresh most plasma makers are using in the 2009 models will increase the moving lines of resolution to close to the full 1080 vertical lines. Panasonic claims they are now at full 1080 lines of moving resolution. To put this in context, LCD is still limited to about 600 lines of vertical moving resolution and the limiting factor is the response rate of the LCD crystals, and no matter how high they make the refresh rate with current LCD tech they cannot achieve 1080p of moving resolution.

They need to improve the RESPONSE RATE much more for those crystals to eliminate the motion blur. They certainly have improved this but who knows if they can ever improve it enough to eliminate the motion blur completely? Some people are more sensitive to motion blur than others just like about 3% of the people saw TBE (the Rainbow Effect) with DLPs.

Hope this helps explain it.

DevilsFan · 07-10-2009, 02:21 PM

Quote:

Originally Posted by PFC5

This is due to the limited response time with current LCD technology requiring more time to retwist the crystals to filter the correct colors that cannot keep up with fast motion and is WHY you have the motion blur. The reason it is not an issue with plasmas (or CRTs for that matter) is because they have response times about 1000 times faster, but this is separate from refresh rates which are how many times the screen refreshes.

I am sure you mean response time right?

As explained above by me, refresh rates and response times are two different things and mostly handle different issues. Increasing the refresh rate on LCDs does help in the perseption of motion blur, but until they can increase the speed in which LCD crystals can be twisted (response time) they cannot eliminate motion blur. Plasma, like CRTs do not suffer this issue.

Higher refresh rates can help with judder though if done correctly (repeating the same full frame an even multiple of 24Fps film), or done poorly with interpolation of those frames which is when you get the "Soap Opera Effect".

Plasma mfg have been touting the subdrive refrech rate as a marketing way to combat the LCD 120Hz or now 240Hz refresh rate marketing. Neither fully resolve issues, but the recent 600Hz subpixel refresh most plasma makers are using in the 2009 models will increase the moving lines of resolution to close to the full 1080 vertical lines. Panasonic claims they are now at full 1080 lines of moving resolution. To put this in context, LCD is still limited to about 600 lines of vertical moving resolution and the limiting factor is the response rate of the LCD crystals, and no matter how high they make the refresh rate with current LCD tech they cannot achieve 1080p of moving resolution.

They need to improve the RESPONSE RATE much more for those crystals to eliminate the motion blur. They certainly have improved this but who knows if they can ever improve it enough to eliminate the motion blur completely? Some people are more sensitive to motion blur than others just like about 3% of the people saw TBE (the Rainbow Effect) with DLPs.

Hope this helps explain it.

Okay, this is very helpful. So in essence, judder is an artifact of refresh rate while motion blur is an artifact of pixel response time. So the 120Hz/240Hz/MotionFlow/AutoMotionPlus marketing gobbledy-gook features are doing nothing to address motion blur but are actually trying to address judder (whether they are doing so successfully is beside the point).

This is all so confusing, and I am an electrical engineer with a pretty strong tech background. It's no wonder Joe Sixpack is so confused about all this.

Loves2Watch · 07-10-2009, 02:47 PM

Quote:

Originally Posted by PFC5

This is due to the limited response time with current LCD technology requiring more time to retwist the crystals to filter the correct colors that cannot keep up with fast motion and is WHY you have the motion blur. The reason it is not an issue with plasmas (or CRTs for that matter) is because they have response times about 1000 times faster, but this is separate from refresh rates which are how many times the screen refreshes.

I am sure you mean response time right?

Actually I meant response time and refresh rate which do go hand in hand.

As explained above by me, refresh rates and response times are two different things and mostly handle different issues. Increasing the refresh rate on LCDs does help in the perseption of motion blur, but until they can increase the speed in which LCD crystals can be twisted (response time) they cannot eliminate motion blur. Plasma, like CRTs do not suffer this issue.

Higher refresh rates can help with judder though if done correctly (repeating the same full frame an even multiple of 24Fps film), or done poorly with interpolation of those frames which is when you get the "Soap Opera Effect".

Plasma mfg have been touting the subdrive refrech rate as a marketing way to combat the LCD 120Hz or now 240Hz refresh rate marketing. Neither fully resolve issues, but the recent 600Hz subpixel refresh most plasma makers are using in the 2009 models will increase the moving lines of resolution to close to the full 1080 vertical lines. Panasonic claims they are now at full 1080 lines of moving resolution. To put this in context, LCD is still limited to about 600 lines of vertical moving resolution and the limiting factor is the response rate of the LCD crystals, and no matter how high they make the refresh rate with current LCD tech they cannot achieve 1080p of moving resolution.

They need to improve the RESPONSE RATE much more for those crystals to eliminate the motion blur. They certainly have improved this but who knows if they can ever improve it enough to eliminate the motion blur completely? Some people are more sensitive to motion blur than others just like about 3% of the people saw TBE (the Rainbow Effect) with DLPs.

Hope this helps explain it.

And to add to that, making faster refresh rates does not compensate for slow response time.

A few companies tried 3 LCD panels so each only had to display 1 color (hence much faster response time). It was so, so much better but for some reason the technology was abandoned.

**rbinck** · 07-10-2009, 03:41 PM

Quote:

Originally Posted by Loves2Watch

And to add to that, making faster refresh rates does not compensate for slow response time.

Not entirely true. If the faster responding pixels, which may be due to over/under voltage during the first percentage of the response time, is combined with 120hz or 240hz refresh where they force a black frame between lit frames, the pixel response blur is minimized.

**PFC5** · 07-10-2009, 06:11 PM

Quote:

Originally Posted by rbinck

Not entirely true. If the faster responding pixels, which may be due to over/under voltage during the first percentage of the response time, is combined with 120hz or 240hz refresh where they force a black frame between lit frames, the pixel response blur is minimized.

Thanks for adding that. But doesn't having a black frame reduce the brightness somewhat? It almost doesn't matter because LCDs can get so bright that you would never really NEED that much light output in a home environment.

Loves2Watch · 07-10-2009, 07:20 PM

Quote:

Originally Posted by rbinck

Not entirely true. If the faster responding pixels, which may be due to over/under voltage during the first percentage of the response time, is combined with 120hz or 240hz refresh where they force a black frame between lit frames, the pixel response blur is minimized.

Minimized but still present. It is the nature of LCD.

07-09-2009, 05:49 PM	#1
DevilsFan High Definition is the definition of life. Join Date: Apr 2009 Location: Chandler, AZ Posts: 109	Motion blur, judder, etc. This is probably a FAQ but I am really confused about the difference between motion blur and judder. Or is there a difference? I've heard that plasmas do not have a problem with motion blur but like LCDs they may have a problem with judder. If I understand judder correctly, it has to do with the difference between frame rate and display refresh rate. Is this a problem inherent in displaying film on digital displays? So what is motion blur if it is not related to judder? What causes it and why are LCDs more susceptible to motion blur than plasmas? Also, do 120Hz and 240Hz displays help address the problems with judder, motion blur, or both? Really confused.

07-10-2009, 11:49 AM	#9
sartor Okely Dokely! Join Date: Aug 2007 Location: Lansing MI Posts: 83	I occasionally have a 'Judder' problem when viewing a DVD on my Toshiba DR560 DVD Recorder. My solution? ->> Just pop the disk into my Phillips 5982 DVD player, and No Judder! The Phillips seems superior at playing a wide variety if disks(including DIVX/.AVI etc), and also seems to totally eliminate judder for me. I have a Sharp 120HZ Lcd HDTV. Both DVD players connected with HDMI cables. __________________ SHARP LC-42D85U Toshiba D-R560 DVD Recorder Sony STR-D1090 + Polk 10A Speakers

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07-09-2009, 06:08 PM	#2
jam269 Wake up and smell the HD Join Date: Jun 2009 Posts: 48	Check this out: http://reviews.cnet.com/4520-6449_7-6792632-1.html Specifically, paragraph entired "Motion blur is a fuzzy concept."

07-09-2009, 06:18 PM	#4
DevilsFan High Definition is the definition of life. Join Date: Apr 2009 Location: Chandler, AZ Posts: 109	OK, so I am sitting in front of a LCD monitor attached to my computer. If I click on the title bar of a window and drag it rapidly across the screen, the contents of that window appear blurred. I assume this is motion blur, correct? It certainly has nothing to do with frame rates or 24p so it's not judder. Is this condition a result of the pixel response time in an LCD?

07-09-2009, 06:27 PM	#5
jam269 Wake up and smell the HD Join Date: Jun 2009 Posts: 48	Judder: In Short: Judder is the result of Film, that is shot in 24 fps (frames per second), but is displayed in a frame rate that is not even multiples of 24 (like 30 or 60). In Not so short: http://www.hometheaterhifi.com/volum...e-10-2000.html (See the section entitled "Re-Interleaving 24fps Film") Motion Blur: In Short: TV can't keep up with the fast moving images. The motion is blurred. In Not so short: http://en.wikipedia.org/wiki/Motion_blur