antart

I can't reproduce the problem in VLC 1.1.13 on my Dell G2410t, DVI, monitor brightness 75%, contrast 50%, Fedora 16.

jkc120

Sorry! I was reading "ROM" as in a read only memory. Like you had two nexuses and one was newer and had a different/newer eeprom or something (indicating a fixed firmware for the video -> screen) or something.

So this ROM just makes it easier to boost brightness/constrast like you can do with screen adjuster? I don't think that's a full fix then...just fixes some cases of the black levels and not the color banding.

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jkc120

Yes, if we could adjust the gamma and other things to that degree on our phones, I am quite sure we could make most of the video artifacts disappear. Since we can't, though, we're at the mercy of what Samsung has hard-coded into their hardware and what google provides an interface to change.

jkc120

Must be in a completely dark room. I mean pitch black. Otherwise much of the problems aren't really very visible. I can see the blue crap on the vampire diaries test clip even in a bright room on full brightness, though.

jkc120

You won't be able to. The videos are optimized for LCD and color levels 16-235 not 0-255. I couldn't see the problem on my LCD laptop either. It's a combination of things:

- SAMOLED technology and its ability to display deep blacks
- videos being encoded with optimized color levels for LCD (see above)
- Samsung's gamma is off

All of those combine to contribute to this problem...

antart

It's likely to be a technology limitation which cannot be fixed, only hidden by reducing contrast. The contrast of the video on the UK GNex is much lower, some areas are very dark where my AU phone shows skin, some hair isn't shown at all on the UK phone. It's not a fix, not even a workaround. My Galaxy Tab 7.7 (non-pentile) shows the details without ugly blue and red marks, and so does the desktop monitor.

jkc120

Both of those devices are LCD or TFT no? This is a samoled thing, but more profound on the note and nexus.

antart

It does boost brightness (tweaked auto is much brighter than non-tweaked auto, tweaked 100% is much brighter than non-tweaked 100%, tweaked 20% is much brighter than non-tweaked 20%, etc.)

If I set both phones to a similar brightness, the contrast of the home screen, browser etc. is approximately the same on both phones, but the contrast of the videos is very different.

I can temporarily go back to the stock ROM on my phone, just out of curiosity, the result doesn't really matter. I knew I was going to buy a pentile phone, just like I knew it wasn't going to have an SD card. It's a PITA, but I wouldn't exchange this phone for any other, released or announced.

antart

Galaxy Tab 7.7 is samoled, but not pentile, true RGB. Sammy calls it Super AMOLED Plus. It would be more honest to call pentile "super amoled minus".

jkc120

I am guessing this is because the ROM allows it to boost the brightness/contrast at a lower level so that HW decoding also benefits from the changes.

With screen adjuster or similar, I believe the only time it affects the video is when using SW decoding.

Have you actually done that to compare? I (and I'm sure others!) would appreciate it if you could try it on the stock ROM or a ROM that does not do these brightness/contrast tweaks so we can determine if the hardware varies or has been improved. If you wouldn't mind doing that, I for one would really appreciate it!

I don't think it has anything to do with the pentile screen, but rather the samoled and samsung's default gamma and the videos being encoded without a 0-255 color space in mind. But if your hardware side by side on the same ROM shows a big difference, we might have our first evidence that it's a hardware problem!

My rant about the ROM was when I was thinking it was a physical hardware ROM that you had noticed was different between the two phones, not a custom software OS ROM

jkc120

The galaxy nexus and galaxy.note both use a newer/different manufacturing process compared to samoled+ so it's not really an apples to apples comparison.

dhworph

How can it be a hardware issue, if software adjustments can change the artifacts appearance? Say if a video player can adjust the contrast, gamma, brightness, and saturation and make it look just like it does on a laptop, then how can it be a hardware issue?

I think the only hardware issue, is that for this specific type of technology to display those "popping" colors, in general, it has to be calibrated this way. i.e. if the contrast & brightness were reduced, and the saturation & gamma adjusted a bit, then while video would look better (or at least more like it would on regular LCD screens), other 'regular' apps like the launcher etc, would look dull and muddy.

jkc120

It could be software to some extent, but adjusting those things is just masking the problem. As you said, calibrating the screen as it is now is how they make it so vibrant and colors pop so much, etc.

I am hoping someone releases a tool like the voodoo screen tuning app for the Nexus so we can fiddle with the gamma. Contrast and brightness alone do not cut it for me, videos still don't look "right". I've pretty much given up on the Nexus being able to act as a video player for me. I'm planning to get a tablet in the 7-9" range to do my video watching.

dhworph

I just think the screen looks amazing during normal everyday use (surfing the web, checking email, texting, phone calls, few apps here and there). It's a bit too bright at night (I wish I had a nighttime mode/theme - that would reduce the colors or something), and on low brightness it looks a bit grainy and grey --- the latter is typical of amoled screen technology, if I understand correctly. Also my white is a bit blue-ish at angles --- maybe mine is defective b/c I hear they are normally yellow-ish at an angle...

And if I had a video player that could adjust the gamma, saturation, brightness and contrast, it would make these highly compressed movies look great (I consider my laptop to make movies look great).

What I think would really say alot abotu this issue is to take the exact same scene - say of the iron man clip - off of the actual DVD and compress it in many different ways and compare them. If someone out there has the DVD, they could take the scene from this test clip, give me the full resolution version, and I'll compress it different ways.

Sandroidfan

Haven't followed this thread closely. But I don't have much issue with Nexus screen for videos. maybe I don't have very sensitive eye. I also have Asus Transformer with 10.1" IPS/LCD screen, which is great for videos. But since I got Nexus, my usage on it has been reduced greatly. I love deep black, high contrast, sharpness on nexus screen.

BlueBiker

Not to excuse them or anything, but rolling component changes aren't unusual in consumer devices. For example, the Dinc had its display changed partway through the model run. I think that's one reason the manufacturers sometimes prefer to keep their public specs slightly ambiguous -- to keep their options open in case they can find a better or cheaper part available later on.

I think the G2410t is a 6-bit monitor, so it may not be able to reproduce the smoother gradients that an 8-bit could.

Well that is where it came from, and yeah it's weird to consider writing to a "read-only" device. Then again, I think some non-maskable interrupts have been maskable almost since the first PCs.

Same difference. Even if it were a hardware ROM, the only characteristic that matters would be the data on it.

Well there's actually almost no difference between hardware and software these days, because so many hardware devices actually have their own embedded CPUs running firmware that the user never sees. In particular, Pentile display panels have some sophisticated (or ugly, depending on how you look at it) image processing that decides how to show original RGB images on the actual RGBG or RGBW display.

Meaning, it's entirely possible that the exact same display panel hardware could show still or video images differently depending on what firmware has been loaded onto it (either originally or through some update method).

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antart

Done. The stock ROM is displaying exactly the same artifacts on my UK GNex.

jkc120

So you have a ROM that you can flash on the GSM nexus that makes the video issues go away? Link please. I'll contact the developer and find out if what they did is applicable to the lte nexus.

antart

No. Sorry for my English.

I have an Australian GSM GNex with a stock ROM which doesn't have the video issues, and a British GSM GNex which does (with either Modaco or stock ROM).

jkc120

What is the manufacture date of the one without the screen issues. If they are shipping newer hardware without the video calibration issues, then I am wondering how they think they can not recall them.

generic username

I can't think of a time when a carrier or manufacturer recalled a phone. Unless users can demonstrate a phone presents a physical danger, I don't see a recall as a realistic possibility.

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Turdbogls

since it seems like there are more knowing people on this subject than i am, i have a question.

now that we have "color control" through custom kernals (Franco's) are there adjustments we can use to minimize this or get rid of it completely?

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jkc120

Not really, no. I was able to use the gamma offsets and multipliers to get the blockiness in blacks to be more gray than purple tinted, but that varies screen to screen.

jonygitar

I did a side by side with my dad's iphone s and this report is dead on, the apple display is bright, the nexus is yellowish

jkc120

The color control feature of some kernels/ROMs allows you to fiddle with the R/G/B gamma and multipliers, so if you have a screen that has the yellowish tinting, you can alleviate it to some extent. Each screen can vary somewhat. I know that my release-day Nexus had a very noticeable yellow tint, but the one I have now doesn't. The whites are much more white on this one (though still not as white as my wife's iPhone 4).

EarlZ

@All who think this is a file quality issue
Answer me this, when viewing this said video on another display medium like the following

Galaxy S
Galaxy S2
Galaxy Tab 7.7
Samsung Wave 1
Samsung Wave 3
Samsung 32" LED-TV
Samsung T220
Dell U2410
Apple 30" Monitor

Does not show any of the horrible quality that is on the screen shot, there are no hints of black clipping on the SuperAMOLED devices even on the list.

Playing around with VLC and adjusting the gamma/contrast/brightness to show the flaws only shows how ignorant one can really be!

@Those thinking this is purely a software issue
You might be right on those since the gamma curve on the Galaxy Note/Nexus is very incorrect as reported by Supercurio

@Those thinking this is not a hardware issue
So why did others had this resolved, especially on the Galaxy Note after a few screen replacements?

Altho this is already a non issue for me since samsung has returned my money and confirmed to me that this is an issue but everyone else is open to speculate on what they think about this issue.

jkc120

YES!!! SO freaking happy right now...

Tried out Lean Kernel 3.2.1exp1 which has the new gamma control features. I can eliminate 99% of the artifacts in videos with this feature! Woohoo!!

Leankernel: Minimalistic Kernel (3.2.1, 4/12/12) - [CDMA] Galaxy Nexus Development - RootzWiki - Page 864

jbdan

Would love to see some before and after shots please. Would really help some people who want a fix for people who are sensitive to this issue.

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jkc120

Unfortunately my wife has my nice point and shoot camera and is out of town, but I'll see if my good ole trusty dinc can take some close ups and I'll post 'em here

jkc120

Well, my old point and shoot doesn't have shutter speed control So the best I could do was trick it by using the "sunset" scene mode. I have to fiddle with color control now, as the gamma=7 made things a bit purplish.

I zoomed in and cropped the pics so you could see it more clearly what's going on.

Here's how it looks with the default gamma:





And now (notice the black is ALL black as it should be):

jkc120

Actually, I take it back. It DOES help with black areas of the video, but it's a trade off. In other places where there was no issue before, now there are some color banding effects. With gamma set to 5, the blacks have the issue. But if I go to 10 the lighter colors have issues. 7 seems to be an ok middle ground for video viewing, but it still has its own issues. So this helps quite a bit, but does not remove the video problems entirely I'm afraid.

Demache

I just want to get this straight, if the artifacts are like the ones in the screenshot I took.



I guess drop box doesn't want to cooperate so here's a URL instead. http://db.tt/5cz1Zdmx

Then they don't seem to be much different than regular compression artifacts. They are just becoming more pronounced. You can see it pretty easily along the dark side of Neo's face and neck.

Last edited by Demache; April 15th, 2012 at 12:51 PM.

jbdan

An excellent comparison wow it is clearly different and better from those 2 pics. Thanks!

TH3ORY

Hi it worked flawlessly on Galaxy Note i had no back blocky clipping issues ??

jkc120

Posted this in a thread on XDA as well, but figured I'd share here.

My friend got an AT&T SGS3 and we were comparing the screens to see if any of the issues with the Nexus screen were still present. All I have to say is the SGS3 screen is night and day better than the Nexus:

- practically ZERO banding, even at lowest possible brightness
- color remains much more true even at lowest brightness
- no tinting I could detect at all, even at lowest brightness
- played back some videos and it's flawless. No artifacts, no color banding/gradients, no splotches.

The screen is practically indistinguishable from an LCD, except it maintains the deeper blacks.

Looks like Samsung really did tweak the hd samoled process technology for the SGS3 screen. I think I'm going to pick one up, once the dev community situation shakes down and I know if I'll have good dev/ROM support.

Kind of sad looking at the Nexus display now.

dhworph

very cool find jkc! thanks for the note on leankernel..

This makes sense though... the OEM peeps have it set so that the colors dont get the issue, but blacks do... they probably picked what they thought was the less noticable setting, which was to make the colors better and the arifacts visible in blacks.

I think they made the best decision, as most people are used to crappy video, and the artifacts are much less noticable on high quality video... but I would love to be able to have freedom to set it (gamma, color balance, etc).

I wonder cranking the gamma in the opposite direction would help some of those people with color banding issues ???