Plasma vs OLED - motion resolution

VierraFan

Active Member
Didn't noticed that (yet), but I noticed vertical bands when switching it on, lasting only for a fraction of a second. However, as long as these things don't appear during normal use (or watching the TV), I don't care about that - they are caused by activating/deactivating the driving electronics (remember white dot in the middle of the old CRT screens when switching them off ?)
 

Xenocyde

Active Member
Sometimes on my amoled screen as it switches to a black screen i can see white sparkles. Which makes me think that perhaps that the voltage is not ideal. Anyone else noticed this on their amoled display i wonder ? - or is it maybe just my screen ?

Haven't noticed this on my Galaxy S. I had it for about 1.5 years now and I have to say I can sense some kind of decrease in brightness.

Also I can sense some small weird orange-yellow spots when looking on white or near-white colors. The spots are not really on the display, as they are moving across the screen when I move my eyes, so it has to be some kind of strange effect caused by my retina... can't really explain what this is as I have never experienced anything similar with any other type of display.
 

stucarblne

Well-known Member
Xenocyde said:
Haven't noticed this on my Galaxy S. I had it for about 1.5 years now and I have to say I can sense some kind of decrease in brightness.

Also I can sense some small weird orange-yellow spots when looking on white or near-white colors. The spots are not really on the display, as they are moving across the screen when I move my eyes, so it has to be some kind of strange effect caused by my retina... can't really explain what this is as I have never experienced anything similar with any other type of display.

Maybe it's just mine then. I seem to not have a lot of luck with regard to voltage on any of my display technologies. My plasma developed red tinted black before i reset it and re adjusted. This phone has white sparkles as it is switching to deeper black to off lol - there is maybe about 20 odd sparkles it's not riddled but still there. Not fussed in particular about the phone though thankfully but the strange voltage is there regardless lol. Weird about these colors you are seeing, maybe it is the display. And that drop in brightness/contrast that you are experiencing is probably going to be the norm time scale wise when the large OLED panels come into big scale production if used heavily. Until they can find refined methods of extending panel life like plasma managed eventually. Especially with the color blue
 

Xenocyde

Active Member
Reading the Official LG EM960V 55" OLED display thread, it seems that they managed to improve lifetime for blue as they are using some special color filters. One reviewer from flatpanelsHD informed me that previous OLED display (19" and 31") had problems with image retention / burn-in. Hopefully, they got rid of this as well with the latest generation.
 

VierraFan

Active Member
They avoided using blue (and red and green) OLED completely. Each pixel consists of 4 white OLED subpixels. Three of them have color filter above (red, green and blue - just like LCD panels), fourth is transparent
 
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ArmitageShanks

Well-known Member
Sparkles might also be the result of a damaged/overheated/overclocked GPU. How hot does your phone get?

My biggest worry for current OLED tech is IR and screen burn. Try this in a dark room: display a bright pattern (e.g. the application icons on a black background) for a few seconds, and then display a medium/dark grey image (I normally just pull down the status bar). On my phone I can sometimes see dark shadows and outlines from the previous image. My SGS screen appears to be considerably more IR-prone than my plasma.
 

Scooby2000

Distinguished Member
They avoided using blue (and red and green) OLED completely. Each pixel consists of 4 white OLED subpixels. Three of them have color filter above (red, green and blue - just like LCD panels), fourth is transparent

Indeed they have though Samsung haven't, so wonder if they figured it out.
 

stucarblne

Well-known Member
VierraFan said:
They avoided using blue (and red and green) OLED completely. Each pixel consists of 4 white OLED subpixels. Three of them have color filter above (red, green and blue - just like LCD panels), fourth is transparent

Thanks.

Seems i will need to read up more on the tech. Wonder how long these new panels will last before a dip is obvious with brightness ?
 

Trollslayer

Distinguished Member
Good, this avoids one potential problem.
 

Scooby2000

Distinguished Member
Sparkles might also be the result of a damaged/overheated/overclocked GPU. How hot does your phone get?

My biggest worry for current OLED tech is IR and screen burn. Try this in a dark room: display a bright pattern (e.g. the application icons on a black background) for a few seconds, and then display a medium/dark grey image (I normally just pull down the status bar). On my phone I can sometimes see dark shadows and outlines from the previous image. My SGS screen appears to be considerably more IR-prone than my plasma.

How close are you looking? my S and now S2 are clear of IR.
 

Insanity202

Distinguished Member
Scooby2000 said:
How close are you looking? my S and now S2 are clear of IR.

Mine has it. Top of the screen where the battery icon, alarm etc are.
 

Scooby2000

Distinguished Member
Mine has it. Top of the screen where the battery icon, alarm etc are.

Never thought to look there as it rarely changes. I did notice my S1s screen was far from black in a dark room if UT had been on a while, S2s a bit better.
 

Insanity202

Distinguished Member
Scooby2000 said:
Never thought to look there as it rarely changes. I did notice my S1s screen was far from black in a dark room if UT had been on a while, S2s a bit better.

If you have the draw somthing app it shows off plenty on that.
 

stucarblne

Well-known Member
ArmitageShanks said:
Sparkles might also be the result of a damaged/overheated/overclocked GPU. How hot does your phone get?

My biggest worry for current OLED tech is IR and screen burn. Try this in a dark room: display a bright pattern (e.g. the application icons on a black background) for a few seconds, and then display a medium/dark grey image (I normally just pull down the status bar). On my phone I can sometimes see dark shadows and outlines from the previous image. My SGS screen appears to be considerably more IR-prone than my plasma.

Hi

I like the free ZD toolbox app it seems to be handy and accurate with a lot of features - easy on the RAM to which is a bonus.

Temp wise it doesn't seem to be getting above 24.5.C which seems about normal ?...

I know what you mean about the image retention i have seen it on many occasions
 

ArmitageShanks

Well-known Member
How close are you looking? my S and now S2 are clear of IR.
I usually can't see it in normal viewing conditions, but in a very dark room it can become noticeable, especially on a pure grey image (same as a plasma, come to think of it).

Mind you, these OLED screens are so bright (even at their lowest settings..which is what I keep my S on) that using it in a dark room is quite painful on the old retinas! :D It's not a retinal after-image I'm seeing here though...
 

VierraFan

Active Member
So, I tried to measure the black level

However, my instrument doesn't go below 0.01 Cd/m2, so I had to use alternative approach. I made a long exposure photo of the phone and my LCD monitor together and analyzed raw data from the camera to determine the black level (they are linear, unlike jpeg from the camera which is nonlinear and heavily processed hence not suitable for that). LCD monitor was set to lowest brightness. In that case it has white level 18 Cd/m2, contrast is 1:860 (determined with several measurements at higher brightness), so black level is 0.021 Cd/m2 (instrument shown 0.02) - similar to black level of UT30 plasma (just that white level is considerably lower because of significantly lower contrast)

First I set brightness of the phone to the maximum. In that case, black level is 0.0019 Cd/m2, while white level is 230 Cd/m2 for 100% white screen, or 290 Cd/m2 for 10% white and 90% black screen (obviously some power management used - like on plasma). Contrast ratio is 1:121.000 for pure white or 1:152.000 for 10% white screen.

By decreasing the brightness to 125 Cd/m2 (this was closest to standard 120 Cd/m2), black level slightly dropped, to 0.00166 Cd/m2. However, contrast ratio was almost halved

Quite decent for a mobile phone, although still short of marketed contrast ratio for even the cheapest LCD TV. :devil:

I attached a photo of first measurement below (it's intentionally slightly out of focus to avoid moire caused by interference between pixel structure of the screen and of the camera).

There are several things to notice. "Black" of LCD monitor has strong blue cast. Analyzing the raw revealed that its color temperature is more than 20.000 K, so I'm wandering why most reviews of LCD screens never revealed this big flaw of LCD screens - whether that data are omitted (in most reviews color temperature is shown from 20 to 100% APL) or are showing values around 9-10.000 K for 0% APL, and my monitor isn't the worst case, because it has CCFL backlight (LED televisions considerably worse) - in some reviews there is a sentence that shadows have slight blue cast and that's it ...

On the other side, "black" of OLED has red cast - color temperature is only about 1900 K. However, while blue tint of LCD is visible to eyes, this is too dark to perceive any color, at least for me. But very dark shadows (up to about 10% APL) also have red or yellow cast. Looks like this type of OLED screen has some problems with low levels of blue. Above 10% APL, color temperature of this screen is around 7500 K.

Another thing to notice is that this OLED has problems with uniformity of blacks, visible as dark dots or patches. However, I never noticed it except on totally black screen and wasn't sure that I see it even on black screen until I made this photo. On the other side, LCD panel itself has almost no uniformity problems with blacks, but however, has problems with non-uniformity of backlight, so it's certainly much worse

Black levels up to video level 19 are crushed - like on UT30 with default settings (however, there is no slider here to correct it)

Here is also a link to a page with similar measurements for some other mobile phones, two of them with OLED

Smartphone “Super” LCD-OLED Display Technology Shoot-Out

As a side note - my LCD monitor (Dell U2211H e-IPS) had maximum brightness 200 Cd/m2 when new, 1 year and 6 months ago. Now, it's only 145 Cd/m2. Contrast also dropped from 1:1200 to 1:860.
 

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ArmitageShanks

Well-known Member
Weird seeing those black spots on the OLED screen, they're too large to be individual pixels. I wonder what causes that? Are they always in the same place on the panel?
 

VierraFan

Active Member
Compared several photos and those dark spots are always at the same place. There are also some vertical bands (not as visible) - also always at the same place at the screen

It's because of nonuniformity of TFT panel driving those OLED pixels. Called "mura" in one OLED book.
Try googling "oled mura" and you will find many complains about this issue from PS VITA users that also has OLED screen
 
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Xenocyde

Active Member
VierraFan, did you test the OLED screen on a Galaxy S? I have a Galaxy S and couldn't notice any black spots in dark room. I can sense some lines on greys, but I think that's the tactile matrix since it has a crosshatched look.

I think I also caught a glimpse of IR coming from the icons in the upper taskbar, but it cleared up pretty fast, in about 5 minutes. I accessed the photo gallery, slid through my photos in landscape mode, paying attention to the right side of the screen. I managed to make out a very faint icon, but I couldn't see any lines coming from the bar itself. After sliding to a fro for about 5 minutes, the icon was almost gone. It seems that this AMOLED screen is probably better than the average plasma screen in terms of IR. I'm still curious to see how the LG 55" OLED fairs in this respect.
 

VierraFan

Active Member
No, I have only this phone

Made another test clip to check can I actually see this mura issue on levels just slightly above black (level 16) in total dark, like camera. It turned out that it's mostly below my perception level. I think I can see some of these dark spots at levels from 20 to 24 which are still very dark. Above that, screen isn't very dark anymore but this issue isn't visible. I think that it wouldn't be a problem even on a TV

However, slight vertical bands/stripes are visible between levels about 24 and about 40, reminding me to similar issues with some plasma or LCD televisions ....

However, LG 55" TV will use different kind of TFT - Metal oxide. That one is said to have considerably better uniformity and is cheaper to produce because only 2 transistors per subpixel needed, while LTPS TFT used in Galaxy (and also in Samsung 55" TV) needs 4-6 to achieve acceptable uniformity.

About the black level, I found a video on Youtube, where Samsung is advertising contrast ratio of this display as 1:150.000. It seems that my measurement was spot on.





According to link I posted in previous post, Samsung was advertising contrast ratio 1:50.000 for Galaxy S. So it seems there was an improvement with S2 screen

Not sure about IR. I think that I noticed very slight evidence of it on dark grey in total dark, but way lower than on Panasonic UT30 plasma

Have yet to check 0.01 ms response time advertised in above video. Unfortunately, it seems that it's only partially true


EDIT: Samsung today announced some technical specifications about their TV. Contrast is declared to be the same as on this phone - 1:150.000, while response time is declared to be 1 ms
 
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VierraFan

Active Member
Yes, it is Samsung Galaxy S II, as I wrote in the very first post when I started this thread (and mentioned in several other posts I think). All experiments were on the display of this phone
 

Xenocyde

Active Member
OK, I looked for the model only in the latest posts and couldn't find it.

Have you found any reviews about the newer Galaxy S3 AMOLED display? Would be interesting to test this new one.
 

VierraFan

Active Member
I didn't find reviews about it. What is known is that it has 1280x720 resolution, pentile pixel layout and the same 60 Hz refresh frequency

So back to response time OLED vs plasma stuff

When I got this phone, I wanted to know how the screen is refreshed and is its response time really almost instant as claimed, so I made several test clips.

It turned out that it is refreshed the same way as LCD, but response time is way better. I attached two photos illustrating this - one of LCD (in landscape orientation) and one of OLED (in portrait orientation)

Test clip consisted of alternated red and green frames at 30 fps. Both displays have refresh frequency 60 Hz, so each red and green frame was refreshed twice. Both screens are constantly refreshed/repainted from top to bottom, each refresh taking 1/60 s. Short exposure photo caught this process somewhere in the middle of painting the red frame over the green. Line "1" is currently addressed line, where voltages on subpixels are changed at the moment the photo was taken, according to change of color from green to red. After this, in case of LCD, liquid crystals start changing their state, so between the line "1" and "2", we see this transition. Distance between 1 and 2 minus duration of exposure (which was 1/500s) is proportional to response time. It is about 3/4 of height of the screen. Since refresh takes 1/60s, response time of the screen for this combination of colors is

(0.75 / 60 - 1 / 500) * 1000 = 10.5 ms

As we can see, for AMOLED, this transition is almost instant. Shortest exposure on my DSLR (used for this photo) is 1/4000s, and distance between line 1 and 2 is almost equal to exposure duration, so response time of the pixels is considerably shorter than 1/4000s. Value in range of 0.01 ms stated by Samsung for this display seems to be real

However, for their 55" TV, Samsung is stating 100x longer response time than for this phone - 1 ms. Also, one site measured "ghosting time" of several OLED displays and result was from 5 ms (15LG9500 - 15" OLED TV from LG, introduced about a year ago) to 17 ms (for display of this phone - Samsung Galaxy S II)

So I had to do some further tests ...
 

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