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galaxy s II display contrast

Hello.
Anyone else noticed that the display is lower quality than sgs ?
I mean in terms of gamma.
I am a photographer and I was amazed how good the contrast and brightness f the first galaxy was, however this one seems to have way too big contrast, making everythig that is dark much darker, giving a fake and strange appearence.
Also the auto brightness in general is lower than sgs.
Does somebody know if it can be tweaked through a kernel recompile, like sharpness and color in voodoo ?

Go to options-->display-->uncheck automatical screen power adjustme(don't know the exact english term, got it in dutch). I bet it is this again...
Let me know... you're not the first one.

No, it's not that but thanks
It's the actual gamma of the driver I think
However I did notice there is now a "background effects" that can adjust saturation and hue so there is access to the drivers. Maybe a bunch of new effects added there like "classic gamma, normal saturation..."

I came from the captivate, and ran just about every rom that was out there. One of the ubiquitous mods was the color fix. I noticed when I first booted the SGS2 up, the color was off (in relation to my expectations) sure enough in display settings there was an option to change it. Without looking I believe it's called "cinema", which perfectly returned that color richness I loved.
Sent from my GT-I9100 using XDA Premium App

there is something wrong with auto brightness , it doesnt work very well , but its not true that SGS 2 has a lower quality display than sgs , Super AMOLED Plus displays are an upgrade to Super AMOLED. They use a real-stripe subpixel matrix and not pentile - and so has 50% more sub-pixels. The PPI is a bit larger but Samsung will soon make them at much higher resolutions. Super AMOLED Plus displays are also thinner, brighter and use 18% less energy than the older Super AMOLED displays.

[REF] Secrets of the S-AMOLED+ revealed - black crush / battery compromise

While we really like the AMOLED+ display for its deep blacks, it also has major flaws:
- Severe black crush (loss of shadow details in dark scenes) when power saving is disengaged (which is the only way to obtain decent brightness)
- Greenish white, which becomes bluish after a few weeks of operation
- Oversaturated greens
- Loss of brightness after a few weeks of use
- Yellowish areas on the screen produced by the deterioration of AMOLED cells through heat, particularly prominent for gamers and overclockers
I wanted to run a few measurements to better understand what could be done at the software level to alleviate those issues. I am listing my findings below, following which I make a few recommendations to Samung, developers and users of the SGSII.
Findings
1. The maximum light outout with "Auto Adjust Screen Power" is limited
Note that the "Auto Adjust Screen Power" option is different to the automatic "auto-brightness" option. All measurements were made with auto-brightness deactivated and maximum brightness.
After measurements the results are as follows:
- Film Mode: 147cd/m²
- Standard Mode:149cd/m²
- Dynamic Mode: 147cd/m²
The lower value in film mode is due to the limitation of green and blue in film mode, which typically produce more luminance.
The lower value in dynamic mode is due to the picture becoming bright too fast above 50% brightness, there is actually white crush happening, as the Power Saving mode is trying to cap power consumption. This is similar to what is observed on a plasma, where Power Consumption is throttled
2. Disengaring the "Auto Adjust Screen Power" option (this is different to the Auto-Brightness option) significantly increases the brightness output
Not many people suspect the impact that "Auto Adjust Screen Power" option has. Engaging that option provides for much higher bighthness (at the expense of battery life):
- Film Mode: 276 cd/m²
- Standard Mode:285 cd/m²
- Dynamic Mode: 283 cd/m²
This is of course is at the expense of battery life but is still useful when trying to read in the sun. Unfortunately, as we will see later, this has a negative impact on shadow details and is not recommended for film viewing.
3. Light output diminishes though intensive use
The measurements after 3 weeks of use consistently show a deterioration of the maximum brightness over time.
Power Saving Engaged:
- Film Mode: 145 cd/m² (-1.4%)
- Standard Mode:147 cd/m² (-1.4%)
- Dynamic Mode: 145 cd/m² (-1.4%)
Power Saving Disabled:
- Film Mode: 270 cd/m² (-2.2%)
- Standard Mode:278 cd/m² (-2.5%)
- Dynamic Mode: 276 cd/m² (-2.5%)
I will continue to monitor this and post updated results in a few weeks.
4. The white balance exhibits a green push, which progressively becomes more bluish over time
I remember finding the whites greenish when I first got the phone. After 3 weeks, I wasn't bothered that much, they looked more neutral to me. I decided to test again after 3 weeks of use. The results confirmed by observations:
- Color temperature shifted after 3 weeks of use, with the proportion of blue increasing at the expense of green
- The color space after 3 weeks displays less saturated green
White balance at unboxing (green push)
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"lightbox_previous": "Previous",
"lightbox_error": "The requested content cannot be loaded. Please try again later.",
"lightbox_start_slideshow": "Start slideshow",
"lightbox_stop_slideshow": "Stop slideshow",
"lightbox_full_screen": "Full screen",
"lightbox_thumbnails": "Thumbnails",
"lightbox_download": "Download",
"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}
White balance 3 weeks later (blue push)
3. Standard and Dynamic mode have the same color space. Film mode exhibits less green oversaturation
Dynamic/Standard Color Space:
Film Color Space:
4. Film Mode with engaged Power Saving has the best gamma
The dynamic mode has got a skewed gama with a white crush
Film Mode offers better gamma
Disengaging power saving creates black crush
When power saving mode is disabled, the loss of shadow details in dark video sequences becomes even more prominent:
As an example, I am including the gamma curve for the least faulty Film Mode with Power Saving disengaged. The much increased light output we saw earlier is at the expense of shadow details:
Recommendations to Samsung
The display clearly has a lot of potential:
-True blacks
- Large color space
- Very good maximum light output
- Standard Mode gamma is pretty linear
[/LIST]
Unfortunately, these qualities are poorly exploited:
- Gamma is overall too high at lower stimulas. Black crush is happening in any mode, thought at various degree
- White balance is biased toward green and blue, which leads to very high color temperatue. Whites are greenish on first year, evolving toward bluish with increased use.
- The color space could be toned down further. Even in film mode, the greens are too saturated
What Samsung could easily do:
- Further reduce light output in film mode by removing blue and green - this would allow for a color temperature of 65K
- Correct the gamma issues: a simple gamma control under the screen settings allowing to shift gamma incrementally across the whole bightness spectrum would allow very decent results indeed
- Although this has less of a priority in my book, allow a color space with further reduced green saturation.
Recommendations to Android Developers
Develop an app allowing to control:
- Bightness
- Contrast
- Gamma
- If possible for each individual color channel
Such an app would be beneficial to all smartphones on the market!
Recommendations to users
- Use the film mode when watching videos in order to avoid black crush, oversaturation and high color temperature. It is still far from the film standard, but will yield the best viewing experience
- Do not disable power saving mode or you will experience significant black crush. Only do so when viewing in bright environments where contrast is more important than accurate gamma.
Closing thoughts
It is obvious when looking at the numbers, that Samsung have struggled to throttle power consumption on the Galaxy devices while still maintaining brightness comparable to the iPhone 4:
When users reclaim more brightness by deactivating power saving, they indeed get nice peak brightness, but this is at the expense of the darker areas, which lose shadow details in order to limit power consumption.
Many users would be happy with an inbetween solution, with brighness around 180cd/m² but more accurate gamma

thanks for the post, but what secrets were revealed? Quite possible I am too tired (2 in the morning my time), but I only see thorough measurements here
How do you explain color space change and brightness decrease in the weeks you had the phone? Is this how quick the OLED light output degrades?

kreoXDA said:
thanks for the post, but what secrets were revealed? Quite possible I am too tired (2 in the morning my time), but I only see thorough measurements here
How do you explain color space change and brightness decrease in the weeks you had the phone? Is this how quick the OLED light output degrades?
Click to expand...
Click to collapse
You ask what secrets were revealed, but then you ask about one of the interesting findings. OLED displays in general are known to degrade over time, as OLED are especially vulnerable to heat.
The degradation you observe is typically more important in the first few weeks of operation, so there is no need to panic. I will continue to monitor this over time and post updated findings.
Why is green most affected? Green is responsible for most of the light output in any display, because it has a high luminance. This is why Samsung's AMOLED exhibits a green push in the white balance, which no other type screen exhibits. Green oversaturation is very hard to compensate with red, and it would likely reduce battery life. You could see green as an economical way of producing more light output at the lowest power consumtion possible.
Balanced greyscale is only achievable if one is prepared to live with a lower maximum brightness on AMOLED's...or insane battery consumption.
I guess, this is the undisclosed truth that Samsung of course will not publicly admit to, but this is what the measurements reveal when you are used to calibrating displays. Basically, Samsung have had to make compromises in terms of white balance and black crush in order to squeeze some extra brightness out of the battery!

I really have no clue what you just wrote in your OP but you seem to know a lot about displays and color. What I do know about the SGS2 is that is shows color banding in gradients maybe you could explain why that happens, is it a characteristic of the display or a software problem?
eg see these threads:
http://forum.xda-developers.com/showthread.php?t=1102766
http://forum.xda-developers.com/showthread.php?t=1075364
http://forum.xda-developers.com/showthread.php?t=1121840

godutch said:
I really have no clue what you just wrote in your OP but you seem to know a lot about displays and color. What I do know about the SGS2 is that is shows color banding in gradients maybe you could explain why that happens, is it a characteristic of the display or a software problem?
eg see these threads:
http://forum.xda-developers.com/showthread.php?t=1102766
http://forum.xda-developers.com/showthread.php?t=1075364
http://forum.xda-developers.com/showthread.php?t=1121840
Click to expand...
Click to collapse
This probably needs to be solved at the driver level, just like the color gamma and white balance issues. This is related and is something that Chainfire could have a look at. That's his domain of expertise after all...
I only calibrate displays. I am totally unskilled as a developer.

Cool so the display is capable of 24 bits color at least?

maybe u can forward this to supercurio. He has some interest as well as experience developing voodoo color for the last gen samsung phones.

MiG123 said:
maybe u can forward this to supercurio. He has some interest as well as experience developing voodoo color for the last gen samsung phones.
Click to expand...
Click to collapse
Great idea. I posted to Chainfire already, but Supercurio may actually be an even more natural choice.

This has me worried "Greenish white, which becomes bluish after a few weeks of operation"
Is there a bedding in period for oled when they are new, like a plasma tv , that they say to keep the brightness low and avoid frozen images and logos for the first 100hrs until the phosphor settles down.
Hopefully the degradation of the colours will slow down.
EDIT : Also any owners of previous generation oled mobiles, how much degradation of the colours and brightness do they show after a few months/years.
EDIT 2 : It looks like the "Samsung W2400 Special Edition" from 2007 is one of the first oled cell phones , I wonder how it`s display is holding up.

puremind said:
Great idea. I posted to Chainfire already, but Supercurio may actually be an even more natural choice.
Click to expand...
Click to collapse
This is indeed a Supercurio thing

What worries me the most is the left side yellow tint ... and samsung says noting.
I went for S2 because of the SAMOLED+ screen and now I get yellow tint for 600€

Thanks for taking the time to do the testing. I'm used to a calibrated environment (I'm a photographer) and I have to say that I really don't like looking at non-calibrated displays of any kind (usually over saturated, too bright and very obvious colour shifts). If anyone can come up with a way of making proper adjustments to the S2, I would be soooo happy

Nice info. Another dirty secret I'm on the fence about is how power hungry white screens actually ate on amoled screens. Look at the test results I did and how power usage spikes to -900 mA just loading a white web page.
http://forum.xda-developers.com/showthread.php?t=998544

RogerPodacter said:
Nice info. Another dirty secret I'm on the fence about is how power hungry white screens actually ate on amoled screens. Look at the test results I did and how power usage spikes to -900 mA just loading a white web page.
http://forum.xda-developers.com/showthread.php?t=998544
Click to expand...
Click to collapse
I am not surprised. This confirms my theory that Samsung indeed hat to fiddle a lot to contain power consumption within acceptable levels, hence the lack of reds across the greyscale, the black crush we observe without screen power auto adjust and the limited brightness output with it engaged...!
Still, I wouldn't mind having a power hungry but accurate color profile that I can engage only as needed! The screen definitely has the potential. The only question is: at what brightness level is a balanced greyscale achievable. I am betting at around 110cd/m². Considering the true blacks this is very acceptable in dark environments (similar to the best plasma screens), but will not be satisfying under day light conditions, which is most of the time...
Still, I wouldn't mind attempting such a calibration providing the right tool is developed.

Tinderbox (UK) said:
This has me worried "Greenish white, which becomes bluish after a few weeks of operation"
Is there a bedding in period for oled when they are new, like a plasma tv , that they say to keep the brightness low and avoid frozen images and logos for the first 100hrs until the phosphor settles down.
Hopefully the degradation of the colours will slow down.
EDIT : Also any owners of previous generation oled mobiles, how much degradation of the colours and brightness do they show after a few months/years.
EDIT 2 : It looks like the "Samsung W2400 Special Edition" from 2007 is one of the first oled cell phones , I wonder how it`s display is holding up.
Click to expand...
Click to collapse
I believe the degradation is visible after a month-two, we just do not want to believe our eyes.
I think when I first unboxed my phone, it looked so much brighter!
And this is how Samsung is selling us these HyperSuperAMOLED+++ "upgrades" - whenever we look at a new version it is by design looking better than our old previous generation AMOLED

Which firmware did you have in the first test and any firmware changes prior to the last test?

jvidia said:
I went for S2 because of the SAMOLED+ screen and now I get yellow tint for 600€
Click to expand...
Click to collapse
100% same here. Nah, seriously I should've gone for the S-LCD displays. S-AMOLED + is still an unfinished product, under development, unless it comes to the stage of a finished and ready for market product we should avoid it. Thanks to OP for doing some good measurements.
Regards.

kreoXDA said:
I believe the degradation is visible after a month-two, we just do not want to believe our eyes.
I think when I first unboxed my phone, it looked so much brighter!
And this is how Samsung is selling us these HyperSuperAMOLED+++ "upgrades" - whenever we look at a new version it is by design looking better than our old previous generation AMOLED
Click to expand...
Click to collapse
It's hard for me to judge if i had any screen degradations on my captivate since i had it flashed to a new rom quite often and i never had the screen on high brightness (never felt the need to do so)

kreoXDA said:
I believe the degradation is visible after a month-two, we just do not want to believe our eyes.
I think when I first unboxed my phone, it looked so much brighter!
And this is how Samsung is selling us these HyperSuperAMOLED+++ "upgrades" - whenever we look at a new version it is by design looking better than our old previous generation AMOLED
Click to expand...
Click to collapse
Note that not all of the degradation is negative. The alleviates the oversaturated greens, and a bluish greyscale is arguably better than a greenish one.
Also, the brightness is still more than enough and bighter than many laptops even after a few weeks of operation.
I will keep monitoring to see how things develop.

ithehappy said:
100% same here. Nah, seriously I should've gone for the S-LCD displays. S-AMOLED + is still an unfinished product, under development, unless it comes to the stage of a finished and ready for market product we should avoid it. Thanks to OP for doing some good measurements.
Regards.
Click to expand...
Click to collapse
Note that the limitation seems to be the battery rather than the display itself. Also the software is responsible for the presets and lack of controls. When Supercurio comes up with Voodoo for the SGSII, we should be able to rectify most of the issues.
The screen is still excellent for films watched in a dark environment if you keep screen power auto adjust activated.
Bightness can be as bright as on a retina display, yes, but at a high power consumption cost.

Low Saturation and Contrast?

Bought the 10...love the way it runs but I bought it to show my photography work on (would use an ipad but I really detest the ios software).
The entire screen seems to be washed out overall with weak black levels and reds in particular are low saturation.
Sharp as a tack for sure....is it just mine? I see such conflicting reports in reviews although I am seeing more now about low saturation and contrast.
Very frustrating....unless someone out there knows some way of calibrating this display which I haven't found?

you are right
i am also a photographer (Canon 5D MkII)
i have watched some photos now(got my N10 yesterday) and as you said the screen is sharp as hell
i have never seen this amount of details with my DSLR photos.
im also doing hardware calibration and i see whats wrong right away and i have also tested it...the problem is that the gamma is to low.
The N10 has a Gamma Level around 1.4 - 1.5 where it should be 2.2!
(yeah that should make some attention hehe)
thats a fact and thats why we have washed out colors and bad contrast
but the good thing is that even at that low gamma we have a decent picture quality with good black levels!
i dont think the black levels on my device is washed out
it shouldnt be this good with this crappy gamma but it is
thats amazing and that tells that this is a quality screen above normal.
with correct gamma at 2.2 this screen will rock for sure.
so lets wait for some kernel guru to make some gamma adjustments
i have said i before that im willing to pay that person that makes gamma adjustment possible for the N10s.

You are correct...gamma is definitely too low.
As far as washed out reds go, I suppose I could process specifically for display on this tablet but that's a pain in the butt.
I wish the darned ipad wasn't such a restrictive ecosystem for the software. The colors rock on the ipad unfortunately but it's just too darned restrictive.

jfenton57 said:
You are correct...gamma is definitely too low.
As far as washed out reds go, I suppose I could process specifically for display on this tablet but that's a pain in the butt.
I wish the darned ipad wasn't such a restrictive ecosystem for the software. The colors rock on the ipad unfortunately but it's just too darned restrictive.
Click to expand...
Click to collapse
im waiting for a i1 Display Pro colormeter
when i get it i will do a hardware calibration.
but i have checked some stuff already and i think that the colors is right for its low gamma.
also the brightness for the colors seems the same for Red/Green/Blue and thats a good thing
also the contrast and black level is reference.
i also think the color temp is close to 6500k
that means that the grayscale is correct.
so the only thing that messes up this display is the low gamma.
(or wrong gamma curve/line)
you have some tests here that you can do without a colormeter,if you want to check it out
http://www.lagom.nl/lcd-test/
also you can download the AVSHD 709 Patterns here.
http://www.avsforum.com/t/948496/avs-hd-709-blu-ray-mp4-calibration
just copy the mp4 files to your N10 and run them.
one note that i can see is that it seems that the gamma is higher at the lower shades
it seems to be around 1.8 there
that could explain why we dont have completely washed out blacks.
but what you want is a plain straight gamma line at 2.2
the N10 seems to have a hill shaped line starting high at lower shades and lower around maximum white.

I have tested the N10 with a Pantone "hocky puck" and can confirm the observations posted above. As compared to overly saturated profiles most normal users are used to, it's no wonder many see the N10 as flat and dull. My N7 is horrible, not only flat but had a color temp that was blueish green.
Much of my publicly displayed work for general web based consumption, has the saturation pumped up farther then I like, but my "fans" (sarc) seem to enjoy my photographs when contrast and saturation is pushed high. Ironically, my over saturated photographs look good to me on the low gamma N10, lol.
Either way, most all of us would benefit from being able to adjust our N10s. As many of you know this is best done at the kernel level and the master of sound and color Samsung kernels is SuperCurio and his project Voodoo. I have heard hearsay that he is working on kernel code and color profiles that can support adjustments for the N10, but I have yet to confirm this myself.
As usual we are given hardware that needs code improvements to be fully realized and that seems to always be done by the development community. It will taken time but I am confident we'll get there to some degree soon.

As far as I could tell there is no gamma correction in the kernel because the Nexus 10 uses a new display port interface thats in the Exynos 5. Most devices I've seen have at least a static gamma table in the kernel but that doesn't appear to be true for the Nexus 10.
Sent from my Nexus 10 using Tapatalk HD

12paq said:
I have heard hearsay that he is working on kernel code and color profiles that can support adjustments for the N10, but I have yet to confirm this myself.
Click to expand...
Click to collapse
give him my money!
that sounds great
post in this thread if you hear more about it!
as i said in other threads i will pay around 50$ for the person that makes gamma adjustment possible for the N10.
btw: hockey puck?
are you serious ?

Dark video looks bad

Anyone else notice this? I took some pictures comparing my iPad Mini (left) vs Nexus 7 2013 (right). The first attachment is from YouTube F4bnVZmdOKs @ 5:31 - notice the splotchiness in the darkest areas. The second is from G-R8LGy-OVs @ 3:56 - notice the halos around the stars. When I watch on my computer (HP LP2065 IPS LCD) it looks much more like the iPad's display.

Looks like video compression blockiness that you don't see on the iPad because of the horrible black levels. If you look at a black still picture do you see the splotches?

Dimethyl said:
Anyone else notice this? I took some pictures comparing my iPad Mini (left) vs Nexus 7 2013 (right). The first attachment is from YouTube F4bnVZmdOKs @ 5:31 - notice the splotchiness in the darkest areas. The second is from G-R8LGy-OVs @ 3:56 - notice the halos around the stars. When I watch on my computer (HP LP2065 IPS LCD) it looks much more like the iPad's display.
Click to expand...
Click to collapse
I agree with the above poster, the splotchiness is video compression artifacts, and if you look past them, and take a step back, you'll actually see that you're getting much more detail and a better gamma on the N7 vs. the iPad. On the iPad side, the woman is completely black, yet on the N7, you can see her face and clothing detail that are simply missing on the iPad.
I would guess that the halos around the stars are similarly missing information on the iPad. With the N7, you're getting the whole picture.

That ipad mini picture is terrible. Talk about crushing blacks. ..... Look at the detail in the nexus picture. I hope your TV is not calibrated like the mini.
Sent from my SAMSUNG-SGH-I337 using xda app-developers app

I think its due to the high DPI. Try any HD video.

Actually the iPad Mini is quite terrible with the loss of dark details.

oh god that ipad looks awful dude.
Sent from my Nexus 7 using Tapatalk 4 Beta

there's probably a video player out there that supports gamma adjustment if it's not to your liking.in a specific video. it's hard to tell from that picture how black crushing the ipad is but some would find it looks "better" when the video is of poor quality. one thing you might want to do is adjust the backlight first (no need to do it global if you've got something like mx player) as the new N7 is supposed to be very bright. in the old n7 you can get away with making mx player always use max brightness because the maximum brightness isn't very high.

Good points. I attached a comparison of the black level test from Lagom. On the Nexus 7 I can see the 1 square easily. On the iPad Mini I can see the 5 square fairly well and the 4 just barely (IRL; hard to tell from the picture). The brightness setting for this and the previous comparisons was 25% on the Nexus 7 and around 55-60% on the iPad Mini. The subjective brightness was similar.

I borrowed an iPad 3 (Retina) to do some more testing. This time to eliminate any variables with video streaming I downloaded the 720P MP4s on my computer and captured stills with VLC. I used Chrome on both Android and iOS to view the images. Same videos as before, roughly the same scenes. The first 2 attachments show the comparisons: iPad 3 on the top, and Nexus 7 2013 on the bottom.
The 3rd attachment is the black level test on the iPad 3. I can clearly see square 2 and if I stare enough I can faintly detect square 1 (IRL; hard to tell from the picture again). The 4th attachment is a comparison of a full white image to show that the brightness is matched fairly closely (easier to tell if you convert to greyscale to ignore white balance differences) - 25% on the Nexus and just a hair above 50% on the iPad.
The 5th and 6th attachments are the source images I used for testing. I converted from PNG to JPG to make the attachments fit, not that it matters much since it's from a lossy source.
I still get the feeling that something isn't right about the way the Nexus looks. I was able to simulate the effect almost identically by applying gamma correction of 1.6 in IrfanView. That would seem to indicate that the Nexus's gamma may be way off, but after I finally found a way to view Lagom's gamma test image without scaling on the Nexus it looked pretty much spot-on correct. It it possible that only the very dark areas are "shifted" in a way that wouldn't affect the gamma test image?
This leads to the last attachment - a new black level test on the Nexus. Again, the brightness was calibrated similarly to the iPad, and the camera was set on full manual mode with all the same settings, so you can directly compare it to the iPad black level test image. Notice how the squares get brighter way faster than on the iPad? It's a lot more pronounced in the darkest squares, but the difference shrinks by the time you get up to the 40 square (last one before full white).

For my final test, I took pictures of Lagom's contrast test image on the Nexus 7 2013 and iPad 3. I then applied a Gaussian blur, converted to greyscale, and determined the RGB value for the first 13 bars. The first attachment is a chart of the results. The brightnesses converge around the 10th bar (RGB = 79 in the source image), but before that the Nexus's brightness is inflated. This explains why the gamma test looked fine, because even in the 10% luminance test, the RGB value of the ideal point is 88. The 2nd and 3rd attachments are the Nexus and iPad (respectively) displaying the test image.

you should bring all this to the "yellow tint" thread. this is a nice showcase on what's wrong with Nexus screen.

I recently purchased an X-Rite i1Display Pro display calibrator. I used it to make really accurate luminance measurements* of the Nexus 7 (2013) and iPad Mini while displaying shades of gray from 0 to 255 in steps of 5. I then calculated the effective gamma** at each step to create the attached chart. It also includes the effective gamma of the reverse sRGB transformation.
My conclusion is that the Nexus is fine if sRGB is the ideal target. I'm not sure what the ideal target is though; in fact, I don't really think there is one. A display gamma calibration of 2.2 to 2.4 seems like the most common recommendation. But almost everyone ignores the fact that sRGB's effective gamma is a lot lower in darker areas. I get the feeling that most people calibrate to a fixed target. sRGB is probably more technically correct. But if fixed 2.2 to 2.4 is more common, does that make it a de facto standard? E.g. if professional movie studios edit their movies on monitors calibrated to fixed gamma, but I watch it with sRGB gamma, doesn't that mean I'm not viewing it as intended by the creator? I'm not saying this is necessarily the case. I'm really, really confused .
So anyway, I just wanted to share my results. You will have to draw your own conclusions.
* I used spotread.exe from Argyll with the -x swtich. The first number from the "Yxy" result is luminance in cd/m^2.
** Effective gamma meaning: the gamma value you'd have to use to get the same luminance value from the input value. Formula is log(luminance) / log(input), where luminance and input are percentages from 0 to 1. I adjusted the luminances to account for non-perfect black levels.

mannequin said:
you should bring all this to the "yellow tint" thread. this is a nice showcase on what's wrong with Nexus screen.
Click to expand...
Click to collapse
I would say the iPad is just warmer (red) and the N7 looks more cooler (greenish-blue) Not by much though, just a few degrees off. No one device is perfect.
With the dark areas, it seems the brightness and/or gamma is too high. I use my screen at half brightness which seems on par with other devices and haven't noticed a big difference.
Hopefully we get a screen calibrator like on the N4 and can make adjust individual adjustments.
Sent from Nexus 7 FHD from XDA Premium HD

Dimethyl said:
My conclusion is that the Nexus is fine if sRGB is the ideal target...
Click to expand...
Click to collapse
all the measurements that you did are only true to the device that you own. the screens in the wild would differ (sometimes drastically) from yours and from one another.

I totally agree with you. I also see lots of artifacts with any dark scene on my 2013 Nexus 7. It doesn't matter if I am playing a higher resolution (HD) scene or lower resolution one. I wish there was a way to fix that.

Dimethyl said:
I recently purchased an X-Rite i1Display Pro display calibrator. I used it to make really accurate luminance measurements* of the Nexus 7 (2013) and iPad Mini while displaying shades of gray from 0 to 255 in steps of 5. I then calculated the effective gamma** at each step to create the attached chart. It also includes the effective gamma of the reverse sRGB transformation.
My conclusion is that the Nexus is fine if sRGB is the ideal target. I'm not sure what the ideal target is though; in fact, I don't really think there is one. A display gamma calibration of 2.2 to 2.4 seems like the most common recommendation. But almost everyone ignores the fact that sRGB's effective gamma is a lot lower in darker areas. I get the feeling that most people calibrate to a fixed target. sRGB is probably more technically correct. But if fixed 2.2 to 2.4 is more common, does that make it a de facto standard? E.g. if professional movie studios edit their movies on monitors calibrated to fixed gamma, but I watch it with sRGB gamma, doesn't that mean I'm not viewing it as intended by the creator? I'm not saying this is necessarily the case. I'm really, really confused .
So anyway, I just wanted to share my results. You will have to draw your own conclusions.
* I used spotread.exe from Argyll with the -x swtich. The first number from the "Yxy" result is luminance in cd/m^2.
** Effective gamma meaning: the gamma value you'd have to use to get the same luminance value from the input value. Formula is log(luminance) / log(input), where luminance and input are percentages from 0 to 1. I adjusted the luminances to account for non-perfect black levels.
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Wow....I just look at my screen. It looks nice.
Not sure WTF all that shizz you posted is about. 250 device = 250 device. /shrug

Mine's right about fine xD .

What can this thing do..

I wonder if the shield can, through a custom kernel, adjust rgb, gamma, or color calibration. similar to a nexus 6p with a custom kernel like franco or elementalx i can adjust to a much cooler screen similar to the galaxy series.
Also I saw in the shields display settings there is a dynamic range setting which i changed to full and the screen seemed to have dramatically changed. the darks seemed much darker. i dont have an hdr tv but a sony bravia about 2 yo so i didnt think it was actually hdr but only the output from the shield.

dontbeweakvato said:
I wonder if the shield can, through a custom kernel, adjust rgb, gamma, or color calibration. similar to a nexus 6p with a custom kernel like franco or elementalx i can adjust to a much cooler screen similar to the galaxy series.
Also I saw in the shields display settings there is a dynamic range setting which i changed to full and the screen seemed to have dramatically changed. the darks seemed much darker. i dont have an hdr tv but a sony bravia about 2 yo so i didnt think it was actually hdr but only the output from the shield.
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full vs limited is in the range that the device will output colors to the screen. with limited the normal range of 0-255 values per color is limited to 16-235. (256 values per color ^3 equals 16,7million colors (3 colors: RGB)
most particularly (older) tv's won't process the full amount of 16,7m colors, in comparison to monitors which almost always do. Reason why is probably cost, to make them cheap, and to save bandwidth. So they compressed the output, losing some of the detail in between (more like MP3 in comparison to using 160kbps vs 320kbps mp3's, most people won;t notice the difference, but it is there unconsciously)
Anyway. by compressing the range, the tv then stretches these out so that those values become the new white and black. Else everything would look greyish and faded. But now you have less detail because you miss some information, because some of the gradient is missing.
Your TV is set up to the limited range, so that it stretches those to be the new black and white. But when you switch the incoming signal to the full 256 range, the tv will still stretch these as if they were the limited range, and it basically cuts off black and white information, making everything higher contrast but losing a lot of information because it's cut off. And then you'll have to set your TV to full as well, but that's not always possible. Because most tv's can't process more color information.
That's why HDR is such a big improvement, more color information, more visible dark and bright gradients and the overall brightness contrast is wider.
But I think in your case by setting it to full you will get the feeling of more contrast, but essentially you are cutting off a bunch of information. You'll probably notice in dark scenes that you can't see much, because it's clipped out.
If this makes sense to you. (I may have made some mistakes explaining this)
Regarding calibration, you should calibrate your tv in stead. There's no use in calibrating your shield. That's only necessary if you can't control your screen, which TV's can, but phones can't. So mess around with your tv color settings.