Thinkpads Forum

The first public video of the x220 is out - and it is a notebook I'd buy in a second:

http://www.mobiletechreview.com/ubbthre ... mber=40140

However I am worried about the backlight:
1. In the first minutes, the display background image is changing a lot. Because it is an animated image?
2. In Photoshop the grey rectangles are changing colors. There is a greyer horizontal 3 cm rectangle from the left to the right moving to the top.

ssd_thinkpad wrote:The first public video of the x220 is out - and it is a notebook I'd buy in a second:

http://www.mobiletechreview.com/ubbthre ... mber=40140

However I am worried about the backlight:
1. In the first minutes, the display background image is changing a lot. Because it is an animated image?
2. In Photoshop the grey rectangles are changing colors. There is a greyer horizontal 3 cm rectangle from the left to the right moving to the top.

LCD has a refresh rate of 60Hz, and the video is probably a 24-29.x fps video, and thus you see those artificial effects. Try pointing your camera, or cellphone in camera mode, to your LCD and you will see something similar.

The reviewer has to be blind or an idiot to not mention that if that was a real issue of the X220 screen.

khtse wrote:LCD has a refresh rate of 60Hz, and the video is probably a 24-29.x fps video, and thus you see those artificial effects. Try pointing your camera, or cellphone in camera mode, to your LCD and you will see something similar.

No apple notebook on youtube flickers. Nor does the ipad. And the affs mod x200s does not flicker on youtube, too. The x300 does. All the newest x20 notebooks from official lenovo youtube channel flicker. The x220 flickers maybe less than the T420. The background is definitely in motion on the review video! I now think, it is a stable picture - if that is true, the screen is far from good.

khtse wrote:The reviewer has to be blind or an idiot to not mention that if that was a real issue of the X220 screen.

Then all reviewer of the x300 were blind in the first place - no one told about flickering. In fact, a very slow led backlight panel seems to be installed there (see my signature).

I want to buy the x220, but I had a bad experience with the x301 I bought for very much money. The x220 is so [censored] un-expensive compared to the x201s, too.

ssd_thinkpad - all LCDs flicker, because of brightness control via PWM. At few hundred hertz. If the PWM frequency is proportional to camera's frame rate, you'll see flickering. Does not mean you'll see it with a naked eye.

fmilovanov wrote:If the PWM frequency is proportional to camera's frame rate, you'll see flickering.

I hope you are right. The x220 looks nice!

ssd_thinkpad wrote: No apple notebook on youtube flickers. Nor does the ipad. And the affs mod x200s does not flicker on youtube, too. The x300 does. All the newest x20 notebooks from official lenovo youtube channel flicker. The x220 flickers maybe less than the T420. The background is definitely in motion on the review video! I now think, it is a stable picture - if that is true, the screen is far from good.

Not true. Go to youtube and search "macbook flickering", you will see a lot of videos of macbook flickering. Some are defects, most are just artificial effect coming from video equipment. Also, when you have glossy screen, the flickering is harder to show on video. I have X200 with AFFS mod, and I just pointing my cellphone camera to the screen. I get the same "flickering" effect as in the X220 review videos, something that I wouldn't have noticed, and definitely still don't notice, with naked eyes.

khtse wrote:most are just artificial effect coming from video equipment.

I understand this. But why do lenovos official youtube videos show flickering notebooks (T-Series)? Because they use inferior video equipment - I do not think so. As much as I understand, the flickering can also occur because of slow backlight frequency. I also understand the camera hz / thinkpad hz problem. By the way: I have yet found a working ipad to see flicker on youtube. Is it because the iPad has a frequency that is somewhat equal to every camera that captures it?

No one ever said anything about INFERIOR camera tech. It's just the nature of how frames are displayed on screen, and how cameras capture each frame. Overlay the function y = sin x with y = sin 2/3 x and you'll see how the graph varies.

Also, I don't know if you've noticed, but most of the MacBooks (and iPads) I see in class almost always have their brightness turned to a really high setting even in the darkest of lecture halls, which would help mask the flickering effect. (I don't know why you need it that bright, but whatever.)

Also, on battery, some of the display power savings modes kick in which lower refresh rate and/or do some funny other stuff for power savings. I suppose the algorithms designed to be not-noticeable to a human eye, with no regard for cameras.

Here is my take on it...

Fluorescent lighting can cause flickering in videos because fluorescent lights actually flicker themselves. It is the difference in frequency between the ambient lighting, display lighting, and camera shutter that make flickering noticeable. Note too that AC mains frequency in Europe and other countries is generally 50 hz., but in the USA 60 hz.

So the location where the video is made (50 or 60 hz), the type of ambient lighting in use (fluorescent, incandescent, or other), the camera shutter speed, the frequency of display refresh, and the pixel response time of the display, are all factors that can affect perceived flickering on videos.

http://en.wikipedia.org/wiki/Fluorescen ... r_problems

Thanks for your input.

Colonel O'Neill wrote:Also, on battery, some of the display power savings modes kick in which lower refresh rate and/or do some funny other stuff for power savings. I suppose the algorithms designed to be not-noticeable to a human eye, with no regard for cameras.

I am very interested in this. How could I know that my thinkpad is doing this? And how could I prevent it?

GomJabbar, the 50 / 60 hz can have obviously something to do it. In this case, the cameras - which should have a picture rate independent of the AC hz - should capture flickering in once hz area much more than in the other. But I think, this is not the case.

And how is it that the iPad does not flicker on youtube videos? Because its screen is always rather bright - could that be a possibility?

The question is - why do you care what flickers and what does not flicker on Youtube videos?

Have you seen any of these screens in real life? Do they flicker when set to normal frequency (60Hz)? If so, then they are bad, regardless of what happens on any video.

From videos recorded with unknown equipment in unknown conditions of a screen running at an unknown frequency you cannot deduce anything.

ssd_thinkpad wrote:In this case, the cameras - which should have a picture rate independent of the AC hz - should capture flickering in once hz area much more than in the other.

Do you know where the cameras picture rate came from?
Usually, in countries with 50Hz AC they use cameras with 25 or 50fps; and in countries with 60Hz AC they use cameras with 30 or 60 or (rarely) 24fps, and this is not a coincidence.

dr_st wrote:Have you seen any of these screens in real life? Do they flicker when set to normal frequency (60Hz)? If so, then they are bad, regardless of what happens on any video.

I saw the very flickering x301 on youtube and was very worried. I was told here the screen was fine and it is just a "camera thing". So I bought the x301 screen. It was horrible. I gave it back. In the end, I learned that the led x300 backlight had a very slow frequency rate - as other very cheap background panels. You can see more about this in my signature.

penartur, that's a good explanation.

ssd_thinkpad wrote:I saw the very flickering x301 on youtube and was very worried. I was told here the screen was fine and it is just a "camera thing". So I bought the x301 screen. It was horrible. I gave it back. In the end, I learned that the led x300 backlight had a very slow frequency rate - as other very cheap background panels.

The fact that specific model flickers both on youtube and in a real life doesn't mean that from seeing some other model flickering on youtube one may conclude it will flicker in real life.
It isn't really about youtube. I think everyone seen a rotating carwheels in movies; and in some movies on some scenes it is clearly noticeable that the wheels are rotating in an opposite direction to one they should rotate in. This is just the difference between how a shooting camera shoots (N still frames per second) and how a human eye perceives (continuous image).

*looks at thread*

Yikes.

It's called temporal aliasing. In real life the displays don't flicker (at least not such that one could perceive with the naked eye).

Yup. Thanks thinkrob.

Maybe the computer was just set to powersave mode with screen refresh rate of 50Hz?

ThinkRob wrote:It's called temporal aliasing. In real life the displays don't flicker (at least not such that one could perceive with the naked eye).

I hadn't heard this term before. I searched for some more information on it and I wonder if you didn't mean temporal dithering instead. Found a couple of interesting links on temporal dithering.

http://en.wikipedia.org/wiki/Frame_Rate_Control

http://en.wikipedia.org/wiki/Flicker_%28screen%29

http://www.lagom.nl/lcd-test/black.php

http://www.tftcentral.co.uk/featurescontent.htm

http://www.pingueculae.com/index.php/computer-monitors

GomJabbar wrote:I hadn't heard this term before. I searched for some more information on it and I wonder if you didn't mean temporal dithering instead. Found a couple of interesting links on temporal dithering.

Thanks for your research. So is it possible that the x200 display is flickering?

I wonder why almost no ipad displays flickering on youtube videos, whether it's a european or an american camera. Flexview displays do not flicker, too! But actuall all lenovo displays flicker on youtube

Could be dithering; it would explain why IPS panels don't suffer from it on camera due to their slow response time.

As long as you're not going to be looking through a camera to look at your screen, flickering shouldn't be an issue.

The IPS x220 flickers on the youtube review videos, too.

@ssd_thinkpad...
maybe just get an x220/ips, if it meets your technical requirements, along with a solid return guarantee if you see flickering first-hand vs via video with unknown recording/playback variables?

fwiw, i've never seen flickering on any thinkpad lcd with any of the machines in my sig. this includes ips and non-ips, led-lit and ccfl. not saying you don't, mind you, just that this observer of many panels hasn't.

good luck in your search.

The flickering is subject. The brain can not see it (only the camera observing the display can let you see this). But the eye of some people adjusts to the flickering whether the picture is displayed or not (the flicker effect). So these people see at the display and everything looks nice, but after some time the eyes feel strange and more tired.

I most likely will buy the x220 to test it directly from US anyway and if I do not like it I will sell it within the EU.

^^^
or you could sell it here, if it doesn't please you. i bet you'd have good luck.

GomJabbar wrote: I hadn't heard this term before. I searched for some more information on it and I wonder if you didn't mean temporal dithering instead. Found a couple of interesting links on temporal dithering.

Unless I'm mistaken, "temporal aliasing" would indeed be the correct term to use to refer to the phenomenon caused by the mismatch between the LCD refresh interval and the framerate of the video(s) in question. *That* is the effect that I was referring to -- not what you see when viewing an LCD monitor in person. Sorry for the ambiguity!