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AMOLED displays cant display true black...:Screen Discussion :...

I posted this on the galaxy s forums too, but it seems a little dead there.
As seen by the NoLED app over in the (galaxy S) dev section, and in a few other places on the net, people are finding that when they display a black image on their amoled/samoled screens in a dark room there is still light emitted by the display. it is not truly black
I would like to know why!
One thing i hear is about image compression and signal noise causing the pixels to not display #000000 black and instead a variant of black/grey causing the pixel to become lit.
This problem is not an issue during the day, i can't tell the difference when my screen is displaying black or off. but what it does effect is battery life.
If the screen isn't powering down its pixels then it is not saving anywhere near as much power as it could do
Were we cheated of our true black?

My phone has the AMOLED. I did notice that I can see the backlight through a black screen, usually during boot up. It dosent really bother me. I didnt feel cheated or anything like that. The images look fine.
My phone could use better battery management, my MT3g battery spoiled me.

The odd thing is that there is no backlight on OLED displays - the light is produced by each individual pixel. It ought to produce true black as the pixels should be entirely off, producing no light at all.

The problem with your analysis is that your using a third party app to test this,
what if the code is messing with the display ????
best way to test this is to upload a black image onto your phone and keep it on for a few hours , now check if the display is consuming battery in the battery usage screen, report your findings here ?
Btw normal AMOLEDS differ from S-AMOLED , they don't have true black so they need to turn on the pixels in the display to display blacks.

They should be the same actually, same technology powering the pixels, same lack of a backlight.
I did my testing on the galaxy S with its super amoled, showing a true black bmp image and the screen is still lit.

There shouldn't be any reason to turn on pixels to display black - black is the absence of light, so creating light to display black is rather counterintuitive.
Pure blacks can't be expected from an LCD because the pixels have to block the light from the always-on backlight, but they ought to be achievable (as far as ambient lighting conditions permit) from an OLED.
I do wonder if this is something PenTile-related, but considering that's a technology designed for OLEDs, you'd hope not!

The PenTile display, iirc correctly, has a white subpixel. Maybe thats where the light is coming from?

ooo .... ooo .... ooo .... does that mean by default no more BLACK screen of death??
On a serious note, i'd find it odd that a program can screw up showing a black screen. Wasn't it usualy a case of (well in my day anyway!) poking #000000 to the "pixels" address? (or however many 0's you need for a true 16bit display)

it cant be because its a RGBW display because each led can still be turned off. there still is no backlight.
Also i doubt its RGBW, most likely RGBG

android53 said:
Also i doubt its RGBW, most likely RGBG
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Yeah, pretty sure it's RGBG. RGBW is a different PenTile layout.

omg you all need a life or a star trek convention to go to lol

AndroHero said:
omg you all need a life or a star trek convention to go to lol
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you DO know YOUR on a geeky phone forum, right?
(Sadly though, i think you are correct!)

AndroHero said:
omg you all need a life or a star trek convention to go to lol
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My life is my phone, and the next StarTrek convention isnt until August 13th in Nj, so until then well debate about screen pixels and how black is black on an AMOLED.

Are you guys using true black? In CMKY terms true black is not 100 100 100 100, or RGB terms 0 0 0. That means 100% color of each of the 3/4 colors. In the printing industry if someone chooses black like this from the color pattern it comes out as greyish black in print.
Heres a good artcle that should help you guys make a true black image in photoshop.
http://www.andrewkelsall.com/the-professional-designers-guide-to-using-black/
Hopefully after reading this you will find that the tests people are using and the color black are very volatile. First make a true black image, then test from there.

maxpower097 said:
.... In the printing industry if someone chooses black like this from the color pattern it comes out as greyish black in print.
...
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A black is easily achieved in assembler (and i'm assuming therefore in C) by simply setting the pixels on the bitmap to 00,00,00 (maybe a few more zero's for more colour range?). This is the "true" black of a device.

i used photoshop to get a high quality uncompressed RGB 0 0 0 bmp image.
the screen is still lit

android53 said:
i used photoshop to get a high quality uncompressed RGB 0 0 0 bmp image.
the screen is still lit
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I'm wondering if thats the best way to test it. If your viewing your image you created in PS it could be rendering it into colors like 1,0,0 , or 0,0,1, etc.... I would imagine you would need to write a program that actually sets each pixal at 0,0,0.

Problem
The display on my s3 mini is not showing true black but a feint gray shade and it has few curved lines that are COMPLETELY BLACK...I'm wondering if I can make the whole display black as there is nothing wrong with the screen...I was unable to capture this on camera as it was too dark

I'm kind of late to the party but...
I saw that problem on my Samsung Galaxy Express (similar to S3) but I moved away from Samsung for a few generations. Now on my A52 I saw the same "problem".
Turns out it's the eye confort shield that turns the screen dimmer and yellowish, it was messing with the true blacks. I disabled it and couldn't see anything at all it was pitch black.
Not sure if that was the problem with my old Galaxy device... But it makes sense that when you notice it the most, is when that eye protection is active.
Hope this helps anyone

Screen colors ?

I was wondering with the screen being so brought even turned all the way down. What colors consume the most power? light or dark

For an LCD I believe it is darker colors, where on the AMOLED screens the lighter colors take up more power.
Does it really require that much more power, where it makes a difference in battery life, I don't think so.

SLCD and Savin Energy??

When i have googled i have found SLCD screens actually consume power blocking bright light...Hence bright wall papers ect are advised rather than dark wallpapers which are recommended for AMOLED.
Is That right???
And my question is i have an SLCD version so using apps like Screen Filter drains more battery??

More correctly, on LCD, the consumed power is independent of screen content. It doesn't matter whether your background is dark or light.
(Unless dynamic contrast is used, where (in case of only one (logical) backlight) the brightest area on the screen would define power consumption. But I never heard of the Nexus S doing that.)
For Screen Filter: The app itselft and applying the filter to every frame will use some power, but I don't think it will be much. But since you don't profit from it anyway, I would get rid of it.

thanks mate will practically test it without the screen filter....and let u know..

for black background SA will save power, however, for white and colorful background, SCLCD will save power.
So, it just so so, not that much different.

[Q] At night, black is not black

Got my OnePlus last night and generally I love it. But I have one showstopper that I'm hoping has a fix that I just don't know about. Is there something wrong with my phone, or is there a fix, or is the problem with me that I’ve become perverted by AMOLED?
See, I use my phone to read at night before bed. Lights totally off, and the black background is just not black, it's grey. My last two phones are a Galaxy S4 and Galaxy Nexus, both of which have AMOLED screens. From what I've read, the AMOLED has a very deep black because apparently the lighting is per-pixel, so the pixel is literally not even on when black is on the screen, right?
So when I read at night, the lit pixels are a deep amber orange, and the black pixels are...black. On the OnePlus, the deep amber orange is washed out (comparatively), and the black pixels are...grey. This is pretty much indistinguishable if there's any visible light in the room, but at night with all the lights off, it’s very obvious since I’m used to the AMOLED black. This shows up in both my ebook reader, Moon+, and in Chrome and Gallery when downloading a "pure black" photo. I even use a program, Screen Filter, to dim the screen down below the lowest brightness setting, but the black background is still too bright for me. And yes, it’s there without Screen Filter.
Again from my reading on this, I seem to find that LCD screens (which the OnePlus has) light the whole screen for their backlight, so this may be pretty much inevitable. Is this accurate?
I’d post a photo, but in the kind of low light conditions I’m talking about, no photo would show that kind of contrast. At least no photo I know how to take.
PS - This does not appear to be the "yellow screen" problem I've been reading about. The colors seem consistent from top to bottom. But I'm not very good at color distinguishing.
Any help is appreciated! Thanks!

You're just used to AMOLED displays, the blacks on those are much deeper because it's not actually lighting up when it's displaying black, it's displaying nothing at all. This is because there's no backlight, each pixel is made up of three LED's, so when it's displaying black none of those LED's are firing up. An LCD display is completely different, even when it isn't really displaying anything (black) it's being lit up by the backlight. There's nothing you can do about this.
Transmitted via Bacon

timmaaa said:
You're just used to AMOLED displays, the blacks on those are much deeper because it's not actually lighting up when it's displaying black, it's displaying nothing at all. This is because there's no backlight, each pixel is made up of three LED's, so when it's displaying black none of those LED's are firing up. An LCD display is completely different, even when it isn't really displaying anything (black) it's being lit up by the backlight. There's nothing you can do about this.
Transmitted via Bacon
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What he said.... the OP can adjust his screen settings accordingly to emulate a "AMOLED" experience as previous phones such as N4,N5 has done this.
http://forum.xda-developers.com/showpost.php?p=54321008&postcount=6 try those settings it might satisfy the OP when it comes to blacks being blacks and not gray

How black wallpaper can save your battery

In the smartphone market the majority of displays are either AMOLED or LCD, but many people don't know that the wallpaper color you choose, yes, wallpaper, can actually make a difference to your smartphone battery life depending on the type of screen with which your device is equipped. Pure black wallpaper, or a dark-colored background in general, can actually save you a significant amount of battery life.
Display tech explained: LCD
LCD stands for Liquid Crystal Display and it's the same kind of technology you'll find in your televisions, monitors and so on. As the name suggests, Liquid Crystal Displays are actually crystals, and as such, they don't emit light of their own but rather transmit light from a light source behind them.
This means that even if you're looking at black on your smartphone or tablet screen, it is actually black lit up from behind. Therefore, LCDs don't really display "true" black
Display tech explained: AMOLED and OLED
Next, AMOLED. AMOLED stands for Active-Matrix Organic Light-Emitting Diode and it is also used for televisions screens but more notably, for smartphones. OLED displays are similar, but do not use an Active Matrix.
Samsung displays, for example, are usually AMOLED: the Galaxy S5, Galaxy Note 3 and Galaxy Note 4 all use an AMOLED display. The LG G Flex 2 uses a Plastic OLED display and the Google Nexus 6 also uses an AMOLED screen.
As the name implies, the screen is made up of organic material that actually produces light when a current is passed through it – electroluminescence. Because AMOLED displays can be lit up pixel by pixel like on the Moto X, black is "true" black because there is no back-lighting.
This also means AMOLED displays are easier on your battery because every pixel is not always lit up.
Battery life: AMOLED vs LCD
AMOLED
You can probably see where this is going: if you have an AMOLED display then you can actually save some battery life by using black wallpapers, or generally darker wallpapers and themes.
little experiment and figured out that you can save about 6% battery life/hour at 20% brightness by using a black wallpaper on an AMOLED display, and about 8%/hour at full brightness.
These results are based on an always-on screen, but the basic theory is sound even if the figures are not exactly set in stone. Another tester using a different method came up with a general 18% saving all day.
LCD
What about LCD battery saving wallpaper, I hear you ask? Sorry, LCDs rely on back-lighting, so there's nothing you can do to save battery there.
The only thing you can do is set your device settings to Battery Saver mode and try not to turn your screen on all the time. Keep your display brightness as low as possible and your screen timeout nice and short.
The good news is you can have the brightest colored wallpaper and themes imaginable and it won't make a difference to your battery. Just think about that when you look at the gloomy screens of AMOLED owners clinging to extended battery life (just don't stray too far from a charger while you gloat).
Other battery life tips for AMOLED screens
There are other things AMOLED owners can do to maximize their battery life too, like setting as many app themes to be as dark as possible.
If you can change the appearance of a bunch of apps you use frequently (or download a different app that does the same thing but that does allow appearance customization), you can save even more battery life.
After all, we don't spend all day on our home screens but more time in apps. You can also set your text and email preferences to be black background and white text, depending on your device and chosen apps.
The easiest way to figure it out for yourself is to fully charge your device as is and wait until it's almost totally dead and look at how much of your battery was used by the display. Just go into your Settings menu and look under Device Settings for Battery.
Make a note of the percentage your display has used up, then, while recharging your phone, switch to a black wallpaper and repeat the cycle to see the difference.

Great app :good: