yashsingh1/xdaforums huggingface dataset:
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
Re: Screen Type: Help us find them! (Franco's kernel)

Thanks!

Right! My desktop monitor has brightness at 17/100. But I think with correct gamma, N4 auto-brightness is not too bad.

Even though what you say is true about Display Tester, fortunately, it doesn't really matter in this thread. All we need is a common tool and protocol to follow in order to sort out screens. Absolute true accuracy is not our first concern. Relative accuracy found in Display Tester is well enough.

Though, I'm trying your image right away if I find the apk... :P
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
Re: Screen Type: Help us find them! (Franco's kernel)

I have been thinking about this. What you say is true in portrait mode. But because we read the gamma values in landscape mode, the app use checkerboard which should take into account the problem with pixel alignment.
[Nexus 4 Q&A, Help & Troubleshooting] elzafir:
Re: Screen Type: Help us find them! (Franco's kernel)

Should I pay attention to grey, yellow, cyan, and magenta as well, or only to RGB when aiming for 2.2?

Sent from my Nexus 4 pimped with AOKP and Franco.kernel
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
Re: Screen Type: Help us find them! (Franco's kernel)

There is no way to control everything with our phone. Our screens is RGB, that's why we do RGB here. All the other colors are productS of RGB. But you can do grey instead of RGB. Forget about the other colors.

Please, read OP before posting. I update the FAQ everyday. Thank you
[Nexus 4 Q&A, Help & Troubleshooting] halluci293:
See this post in the franco thread for the test image and my calibrated results: http://xdaforums.com/showthread.php?p=38317892#post38317892

Using this gamma test image modded into franco's app, I tested all of the settings so far in this thread to check gamma over the full luminance range (every step from 0-255), and across different color channels. (for technical details about how the gamma calibration image works, see this: http://glennmessersmith.com/images/adjust.htm#how). Ideally, when viewing the image at 1 to 1 pixel resolution, you will not see any color bars, and the gradient from black to white should be uniformly smooth.

I don't have exact gamma numbers, but this is what I observe in terms of deviations from 2.2, and gradient smoothness (flat means that the luminance change I see in that range of the gradient seems to plateau, resulting in bands of non-uniform gradient).

K:

significant gamma deviations from 10-50% luminance, mild deviations above 90%

gradient is smooth up to 70%, flat region above 70%

O:

significant gamma deviations from 10-15%, 50-70%, mild deviations above 70%

flat bands in the gradient at 25-50%, and above 70%

V:

medium deviations from 15-25%

gradient appears smooth

C:

medium deviations from 10-60%, mild deviations above 60%

flat band above 70%

One more observation, for those of you who stick to RGB 255; If I have my RGB settings at max, the rightmost colored box on Franco's calibration test image in the app is clearly much brighter than the rest of the gradient. Do you guys notice this? When setting your colors, every single block in that image should be distinguishable, and moving left to right you should see a uniform progression in brightness.
[Nexus 4 Q&A, Help & Troubleshooting] elzafir:
Re: Screen Type: Help us find them! (Franco's kernel)

Ah thanks.

Sorry I didn't read the OP. It's because I have read it a few days ago, never thought you would update it. My bad.

I got 2.2 on RGB, 2.4 on gray with slimdj's values:

RGB: 255

Gray: 0

Mids: 119

Blacks: 119

Contrast: 0

Brightness: 0

Saturation: 7

White: 4

Tested on 50% brightness. Daily usage is with auto-brightness.

Which screen type does mine belongs to?

212K, rev_11, franco.kernel r86.

Sent from my Nexus 4 pimped with AOKP and Franco.kernel
[Nexus 4 Q&A, Help & Troubleshooting] yokuyuki:
You should try the four types first. I found slimdj's pretty close to obsanity and ceejay's.
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
Thanks. But this discussion has no meaning if we don't know what screen you have and it's the purpose of this thread. Please read the OP and follow the protocol, use Display Tester, give us your results then we can talk about the differences with your method and analysis. Because right now, you are not helping in anyway as there's no bridge from your knowledge to ours. Please give us your gamma with Display Tester for the settings provided in OP.

And again, if you didn't read my replies to your previous post. Absolute screen accuracy has no meaning to us for the goal of our quest here. Banding, no banding, correct saturation or not don't matter at all. 2.2 RGB gamma in Display Tester with the provided settings is all we need here to be able to discriminate screens type. For screens accuracy, post in our sister thread.

Please everyone, do read the OP CAREFULLY. Talks here are useless if we are not on the same page.
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
We can't tell you if you don't provide us gamma results for the settings provided in OP. We don't want new settings unless there is a significant difference. We can't do any analysis with the current information. Thanks.

I agree. SlimDJ, Obsanity and Ceejay's settings are probably just a standard variation of the same screen.
[Nexus 4 Q&A, Help & Troubleshooting] halluci293:
Sorry for derailing the thread a bit, I merely wanted to point out that just because you can match 2.2 in display tester at 50% luminance with one of the 4 configurations, that doesn't mean there are only 4 types of screens, since there could be significant variations outside of the 50% luminance range.

To contribute to the OP: using display tester, 50% brightness, gamma for KRGB | Avg (averaged values if lay inbetween)

K: 2.6 2.3 2.4 2.4 | 2.43

O: 2.5 2.1 2.1 2.2 | 2.23

V: 2.5 1.8 2.0 2.0 | 2.08

C: 2.4 1.9 1.9 2.0 | 2.05

[Mine: 2.5 2.0 2.1 2.1 | 2.18]

Display tester gamma differs quite significantly compared to 50% luminance with my test image. Also, although the above might suggest I have a type O screen, I'm not so sure since I get WAY overblown whites.

212k, rev11 by the way, lcd_maker_id string not present in dmesg.
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
Thank you!

Overblown whites are OK for what we need. At no point do we pretend any of the settings provided are good or accurate, they just give 2.2 gamma for RGB. All we can say is Type O is the most common screen it seems. I have to contact VisceralPsyche and make sure that his screen is actually O or K.

I can't give any opinion about your method for measuring gamma, because my screen is not the same as yours. But I'm sure someone will answer your questions.
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
Guys, I'm not the only one! :P
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
Yeah, I have that too. That should not happen, too much saturation or contrast. That usually happens with poor quality monitors.

Spot on, reducing RGB color attenuates that weakness of our screen.

EDIT

But reducing RGB values reduces black constrast to inacceptable levels and creates some kind of banding with my screen.
[Nexus 4 Q&A, Help & Troubleshooting] elzafir:
Re: Screen Type: Help us find them! (Franco's kernel)

Okay, I'm testing the OP values.

KelGhu: 2.8 gray, 2.6 RGB

Obsanity: 2.6 gray, 2.2 R, 2.2 G, 2.3B

VisceralPsyche: 2.4 gray, 1.8 R, 2.0 G, 2.0 B

ceejay83: 2.4 gray, 2.1 RGB

Sent from my Nexus 4 pimped with AOKP and Franco.kernel
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
You're type O, like most people.
[Nexus 4 Q&A, Help & Troubleshooting] DesertVelo:
Re: Screen Type: Help us find them! (Franco's kernel)

Try running the command right after a reboot.
[Nexus 4 Q&A, Help & Troubleshooting] ol@fson:
According to that internal LGE document about revisions those hw revisions are mainboard related only. Meaning rev 10 is PCB 1.0, rev 11 is PCB 1.1 and so on. So it should actually have nothing to do with the display type. It is most likely that the displays vary on production date and availability during the process of assembly.
[Nexus 4 Q&A, Help & Troubleshooting] Soul Monkey:
Here are my results/values:

Type K - R 2.6 G 2.6 B 2.6

Type O - R 2.2 G 2.2 B 2.3

Type V - R 1.6 G 1.8 B 2.0

Type C - R 2.1 G 2.1 B 2.2

212K

HW rev = 11

kernel r86

corrected values used

lcd_maker_id primary

looks like type O for me
[Nexus 4 Q&A, Help & Troubleshooting] halluci293:
New test images are up in Franco Kernel Updater! For all of you who are type 'O' screens, what do you observe on the different test images? I'm especially curious about the last one since that should tell you how close you are to 2.2 gamma at every luminance value. If we take a picture of our screens with a camera on the gamma image, we should be able to compare and check if all 'O' screens are indeed created equal.

The new images are, in order:

black/white levels:

- top half shows black checkerboards increasing in steps of two; the lower the number that you can still see the checkerboard, the better black levels you have (I can see 6 at max brightness with my calibration)

- bottom half shows white checkerboards increasing in steps of one; the higher the number that you can still see, the better (I can see 254)

KRGB gamma at 75%/50%/25% luminance going from left to right, top to bottom:

- all squares should blend into their respective borders. The fourth image is a more rigorous gamma test than this one.

Color banding for KRGB:

- all gradients should be smooth even transitions from left to right.

Gamma at every luminance step from 0 to 255:

- all bars should blend in with the black to white gradients. any color casts you see are deviations from 2.2 gamma.

- the top horizontal strip is 0-255 with the gamma test bars in vertical orientation

- the bottom strips are 0-127, 64-191, and 128-255 luminance steps from left to right respectively

- this also doubles as a banding/gradient test, as the background black to white gradient should transition smoothly everywhere.

I've attached pictures of what the last test image looks like with each of the OP presets, and my calibrated one. Ignore the bad focus on some of the images, my point and shoot camera is 7 years old... they match what I observe visually though.
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
Give us your settings for that last test in order to compare equality.

For Type K screens, there's no way I can get what you have by play around with gamma. I have to tweak RGB now though.

Is KRGB gamma (test 2) good when you have good gamma for all luminance (test 4)?

What does stock settings show?
[Nexus 4 Q&A, Help & Troubleshooting] halluci293:
My settings in the last image are:

RGB 200,190,185

Gray 0

Mids 23

Blacks 119

Contrast 0

Brightness 8

Saturation 23

Whites 0

Pictures were taken at 50% brightness.

Test 2 is good when I have good gamma in test 4. For Obsanity's settings, 25% and 75% gamma are pretty close in test 2, but 50% gamma is definitely off.

I found that RGB settings have a fairly big effect on gamma in test 4. At anything greater than 200, I could not get good gamma in test 4 by just tweaking gamma parameters, the above RGB values are the maximum I could set while still maintaining good results in the last gamma test (I then adjusted the relative RGB ratios to correct for color temperature on my screen). My suggestion is to start with RGB at 175 (I know it will seem dark), play with your gamma settings until test 4 looks good, and then incrementally raise your RGB in steps of ~10 while making small adjustments to keep test 4 looking good, until you can't do so anymore.

Edit: Added stock photo. Stock has bad gamma for test 2 at 50% and 25% luminance.
[Nexus 4 Q&A, Help & Troubleshooting] steviewevie:
Re: Screen Type: Help us find them! (Franco's kernel)

Wow! Thanks for the nice info about how to use these. I thought that obsanity's settings were giving me pretty good gamma based on Display Tester, but now my own view of that fourth test is nothing like yours, I still have colour cast :(

Sent from my Nexus 4
[Nexus 4 Q&A, Help & Troubleshooting] halluci293:
Have you tried my settings from the post above? What is your experience with that (keep in mind that RGB setting is also important).
[Nexus 4 Q&A, Help & Troubleshooting] steviewevie:
Re: Screen Type: Help us find them! (Franco's kernel)

*falls off chair*

It's perfect on that image with your settings, thank you!

Sent from my Nexus 4
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
For Type K, using halluci293 method:

RGB 185

Greys 0

Mids 6

Blacks 119

Contrast 19

Brightness 15

Saturation 7

Whites 0

This is one possibility for Type K. I don't know if there can be any other. I'll refined this. But this works.

I'll add this to OP. We'll make this method the main method for comparing screens. Thanks to halluci293!
[Nexus 4 Q&A, Help & Troubleshooting] jimgreco:
All tested at 50% gamma, looks like I have a "C" screen. Colors look great but the greys are very off, way too dark for my taste.

K) R3.0 / G2.8 / B2.8

O) R2.3 / G2.3 / B2.3

V) R2.0 / G2.1 / B2.1

C) R2.2 / G2.2 / B2.2

212K, rev_11, franco.kernel r86.
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
OP has been updated with new method. Please retest your screen and provide us your results!

Thank you!
[Nexus 4 Q&A, Help & Troubleshooting] Soul Monkey:
Are we still supposed to check the gamma values for rgb with the display tester app?

Those new settings for type H give me in display tester app 2.0 for red and 2.2 for green and blue.

I tried some variations myself and have found settings that - at least on my screen - give me 2.2 for red, green and blue in the display tester app and slightly better black (4) saturation on the 'checkerboard' in the franco kernel app. However the last test image in the franco app is not as nice as the one for type H.

So what is more important? Best smoothness in that last test image in the franco kernel app or gamma in the display tester app?

my settings are:

rgb 245

grays: 0

mids: 7

blacks: 103

contrast: 24

brightness: 7

saturation: 4

whites: 0

I am not posting these settings to bring more confusion into this topic, but wanted to share what I found.
[Nexus 4 Q&A, Help & Troubleshooting] halluci293:
Use the last test image in the kernel updater app to calibrate gamma; this is the best test for true 2.2 gamma at every luminance level. If you are at real 2.2 gamma, you should see not see any color casts anywhere. You do not need to use display tester anymore.

I am a little suspicious of display tester's gamma test, and the new images in the franco kernel updater app should be a better test for whether or not you are at 2.2 (note they do not tell you what exact gamma you have, but will let you know whether or not you are close to 2.2).
[Nexus 4 Q&A, Help & Troubleshooting] steviewevie:
I don't know how relevant this is, but as well as the fact that halluci's settings give me a pretty much perfect image for that fourth one in Franco's app (as I said before), also in Display Tester I do get spot-on 2.2 gamma for RGB (but off the scale for grey, and also quite a bit off for the other colours).

Sent from my Nexus 4
[Nexus 4 Q&A, Help & Troubleshooting] ol@fson:
Using the new settings for Type-K I get a perfect match in FKU app but around 1.6 for RGB gamma in display tester. So which one to believe? ;) Anyway I prefer the old "display tester proven" colour profile.
[Nexus 4 Q&A, Help & Troubleshooting] halluci293:
Interesting... I just tried your settings Kel, and they also give me a pretty good calibration on test image 4. Perhaps type H and type K are the same screens after all? Have you tried my calibrated settings?
[Nexus 4 Q&A, Help & Troubleshooting] enursed:
AW: Screen Type: Help us find them! (Franco's kernel) - NEW METHOD PLEASE RETEST!

212K, Rev_11, primary, r86, corrected values:

Formerly type O was good for me, but now I retested with Type H and K on 4th image and type K settings give me almost perfect gamma!
[Nexus 4 Q&A, Help & Troubleshooting] Soul Monkey:
212K, Rev_11, primary, r86, corrected values

The new values for type K give me a pretty good look in the 4th image. Type H has slightly green strips in that image for me, so type K for me.

But type K gives me a brighter overall screen so I have to lower my display brightness so it looks better.

It seems there are many(?) possiblities you just have to find the right rgb gamma levels first and than play around with those other 7 settings. Are the possibilities 'equal' and just vary in brightness or are there other things that could be adjusted?

For example how important is the white/black checkerboard image? Do you need to be as close as possible to black (2) and white (254) or does it not really matter for a mobile phone? I cannot find values (3 rgb gamma and those other 7 values) that give me a perfect 1st and 4th image, it's just one or the other.

The next question would be is it possible to adjust the 7 values first (for example to have a good 1st image) and than just find the correct rgb gamma values to make image nr. 4 correct? That's pretty hard to check right now because you have to go back and forth between menu screens and when you change the 3 gamma values you just see the effect they have on the screen/color but not the effect they have on the images.

I guess it would be better to have the images and all 10 sliders on one screen so you could change the values around and see in which way they affect those test images.

I have no experience with these calibration/gamma things so bare with me if my thoughts about this are just plain stupid.
[Nexus 4 Q&A, Help & Troubleshooting] Anytime1157:
What I can say with the new test is that with type H I get less banding than type K. Didn't test out display tester though, just fku :)

212K Rev11
[Nexus 4 Q&A, Help & Troubleshooting] steviewevie:
I get equally good results (to my eyes) for both the new H and K settings now, based on the fourth gamma pic in fku, no banding, also gamma 2.1/2.2 in Display Tester.

Sent from my Nexus 4
[Nexus 4 Q&A, Help & Troubleshooting] DesertVelo:
210K Rev10

primary lcd

R90 corrected

50% brightness

Best result (ever so slight) is type H

Sent from the singletrack...
[Nexus 4 Q&A, Help & Troubleshooting] Kel Ghu:
Yeah, it seems the new method tells us the screens are the same. But we do know they are actually different. This leads me to thinking that we have found a common origin point for all of our screen, something that should have been the factory settings. But that screen response vary for RGB set above and below 185.

The new method is good, but not for the new purpose of this thread which naturally becomes defining screen response type. The reason is we can't easily discriminate screen response with the new method. Display Tester is better at showing a difference there because there's a scale we can rely on.

We will use both method:

- New method to make sure screens are the same and thus will be base settings.

- Old method to measure screen response to variation from base settings.

I'll update the OP when I have time.
[Nexus 4 Q&A, Help & Troubleshooting] Whosdaman:
Okay so my Nexus 4 is rev 10 and its LCD is primary. I am running the latest CM10.1 nightly with r91 franco kernel at 50% brightness. I don't know how to find out the "301K" part...but here are my results.

As well, I was able to identify a potential testing problem. It seems the "white" setting when set to 0 will not stick after reboot. In order to test properly, you must adjust the white setting every time.

Settings changed using franco.Kernel updater app. Data collected using Display Tester app. No uncorrected color calibration settings were used.

*Unk - unknown due to unmatched results in gamma tester.

Current:

H

Gray: Unk

Red: 1.8

Green: 2.0

Blue: 2.1

Yellow: 2.5

Cyan: 2.5

Magenta: 1.8

K

Gray: Unk

Red: 1.8

Green: 2.0

Blue: 2.0

Yellow: 2.3

Cyan: 2.3

Magenta: 1.7

Old:

V

Gray: Unk

Red: 1.8

Green: 2.0

Blue: 2.0

Yellow: 2.3

Cyan: 2.2

Magenta: 1.6

C

Gray: 2.4

Red: 1.8

Green: 1.9

Blue: 2.0

Yellow: 2.2

Cyan: 2.1

Magenta: 2.0

O

Gray: 2.5

Red: 2.1

Green: 2.1

Blue: 2.2

Yellow: 2.4

Cyan: 2.3

Magenta: 2.0

K

Gray: 2.5

Red: 2.3

Green: 2.3

Blue: 2.3

Yellow: 2.5

Cyan: 2.5

Magenta: 2.2

I am going to do more testing with my device, but it seems there is more work to do. Please assist or advice if necessary. Thanks!
[Nexus 4 Q&A, Help & Troubleshooting] halluci293:
I think the theory of one screen type with small variations in response makes a lot of sense, since unless there are different LCD manufacturers sourced by LG for these phones they should all be roughly the same. However, all LCD screens, even from the same manufacturer, will have small variations in response, so people should start with a 'rough' calibration based on configurations here and fine-tune to their particular screen response. It's possible that LG may at some point change their LCD production line which produces a screen that shows significant difference from the current batch, but I think the evidence points to the same LCD source so far.

So anyway, I did a bit more playing around with gamma settings, and it seems like there are many different configurations that give near perfect gamma. In particular, these are my observations:

grays: small effect on gamma in the top 70-90% of the gamma range, I found that generally keeping it very low (i.e. 0) was best

mids: 7 or 23 seem to be optimal

blacks: 119. Anything else and the darks just get messed up.

contrast/brightness: these are linked and have offsetting effects, i.e. if you raise brightness, you need to raise contrast to compensate. To me, it seems like if you raise brightness too much, compensating gamma-wise for contrast reduces the overall contrast of the screen (blacks are not as dark).

saturation: 7 or 23; 23 is less friendly for raising contrast but allows for lower brightness value while 7 gives you more freedom to raise contrast/brightness

whites: keep this low; anything higher than 0 quickly saturates the upper end and leads to blown out whites.
[Nexus 4 Q&A, Help & Troubleshooting] CrimsonSmear:
Would it stand to reason that a suggested default of:

RGB:180

Greys: 0

Mids: 7

Blacks: 119

Contrast: 15

Brightness: 15

Saturation: 7

Whites: 0

be a baseline setting that falls within tolerances and that fine tuning proceed from there for individual screens/preferences?
[Nexus 4 Q&A, Help & Troubleshooting] milesmarrero:
Being calibrated according to the 4th image using K settings doesn't get me near 2.2 on the display tester app at ALL. My screen looks cloudy and not even one of the strips in display tester blended in with the background, 301k I assume to be rev 11
[Nexus 4 Q&A, Help & Troubleshooting] Whosdaman:
I will say my whites have a green tint to them...and idk how to fix that lol
[Nexus 4 Q&A, Help & Troubleshooting] milesmarrero:
So what is the difference with the color/gamma calibration in Franco's kernel and the one in motley's /faux's kernel with the amp 0/amp1?
[Nexus 4 Q&A, Help & Troubleshooting] jtwlbz:
301k here. betweek K and H. both look good but H is the one i like.
[Nexus 4 Q&A, Help & Troubleshooting] Whosdaman:
Using H's new method and image, H is the perfect setting for rev 10 primary displays. But its rgb gamma is terrible.
[Nexus 4 Q&A, Help & Troubleshooting] jak3z:
Using display tester:

Grey: Green tint and not close to any gamma

Red: 2.2

Green: 2.2

Blue: 2.2

Yellow: 2.6

Cyan: 2.6

Magenta: 2.0

210k + r90-test + primary

Using Type H.

Looking at the 4th image in the franco app I see a perfect blending like suggested in the OP. What bothers me is the display tester grey gamma test, with green bars all round.

I took a photo of the grey gamma, using manual mode with low lighting just so everyone can see what I'm talking about.

High-res image: http://img826.imageshack.us/img826/9006/img0889hy.jpg (1.2mb)

Low-res image: http://img9.imageshack.us/img9/6595/img0889lowres.jpg (160kb)
[Nexus 4 Q&A, Help & Troubleshooting] steviewevie:
I get the exact same thing, but it doesn't bother me because everything else looks fine to my (admittedly untrained) eye.

Sent from my Nexus 4