Calibrating my Nexus 7 (2013) to standard sRGB 6500K

First attempt & beta profile

I'm currently writing a solution that will, as absolute first on market to calibrate your tablet using a colorimeter or spectrophotometer.
No erratic slider tuning here, this is the real deal with 256 values per channel.

With this solution, Nexus 7 (2013) will becomes a tool of choice for professional photographers and graphic creators to showcase their work on the go, thanks to a display that might rival their desktop monitor in terms of color reproduction accuracy.
As there's always variation between devices in production, the key is to allow the user to calibrate his device on his own.
(It requires having access to a sensor)

So far, color calibration has not been a priority of +Android Developers or manufacturers:
Most devices are released without any calibration effort, and Android OS doesn't provide any solution to the situation either, being incompatible with ICC profiles.

I'm very early in the development of this solution as I got my tablet yesterday, but in the meantime, here's some measurements with a profile targeting D65, the standard sRGB white point.

+Romain Guy there's a few photographers in your dev teams. Do you think anyone would be interested integrating such feature in Android?

– Contrast ratio is 1103:1
– This is my very first attempt, I'm sure even better results can be obtained.

#supercurioBlog #calibration #display #color #development


In Album Nexus 7 (2013) first D65 display profile

Source post on Google+

Published by

François Simond

Mobile engineer & analyst specialized in, display, camera color calibration, audio tuning

34 thoughts on “Calibrating my Nexus 7 (2013) to standard sRGB 6500K”

  1. N7 2013 only in the beginning.
    After that I hope supporting every device that has a sRGB gamut capable display and the hardware & driver capabilities.

    Nexus 10 display gamut doesn't cover sRGB gamut which makes it a not so good target, even if boosting the color saturation could be used to cheat partially.

    Ideally it will be a temporary development effort relying on root to showcase what should be possible to +Android Developers and manufacturers.
    Buying dozen of devices to write a driver and support them cost too much money and time ^^

  2. +Rowan D as usual I target stock firmwares instead of custom-firmware specific.
    My goal is to make mods accessible to most users, especially those not having the time to flash and maintain custom software.
    Remember here the main target will be photographers.

    For APIs I expect Google would make an implementation from scratch, capable of not only calibration but also colorspace conversion on the whole OS. This is the proper way and I bet they would ignore a prior API and implementation.

    Expect root as only requirement. If broken by a hazardous ROM modification or regression: too bad, but for the N7 2013 I expect the compatibility to be large as I plan a userspace implementation using existing kernel APIs.

  3. Andreilux over on XDA did a colour calibration for the S3 & S4 Exynos for his kernel. Screen is awesome with colour calibration so to all those Nexus 7 guys you are going to enjoy the new look ;).

  4. +Rowen Nortje this is not comparable in any way, what you describe is a misuse of the term calibration.
    AMOLED panels have a very large variance in color rendering between samples due to inconsistency in the manufacturing process and weak factory calibration.
    You cannot calibrate every display with a single parameter for everyone.

    Actual calibration of a display using a sensor is the standard usage for years on computers, video and print for years, that's what I intend to bring on Android platform.

  5. Ah so you are just providing a app to interface within Android? Will have to save up to buy one of those devices then. For now I will stick to what Andrei did to get as close as possible to proper colour calibration since I don't have access to said tools. Will be keen to see how this works once you have a finished product :). Apologies for spamming your post…

  6. Yes, per definition calibration requires a sensor (colorimeter or spectrophotometer) that will take readings of the actual display.

    Those readings are then computed by software to match a defined response curve. in this case gamma 2.2 or preferably sRGB one:

    I also have an app/driver in preparation for tuning SuperAMOLED displays, also capable of improving color rendition accuracy − that don't require flashing any custom kernel. But I wouldn't dare calling this calibration 🙂

  7. 2 questions +supercurio François Simond . I have a Spyder3 Elite, what I love, and use on Windows and Linux also. Are you try to make a real application for use maybe this colorimeter also, without real Android ICC support? The second one is just a practical one: did you tried to calibrate OLED screens (if I remember correctly you had one Galaxy S then Galaxy Tab 7.7, etc…)? What do you think about it's usual gamut? Large, small, compared to SRGB or Adobe RGB?

    Thanks for your answers in advance!

  8. Hi +Tamás Tóth.
    Yeah Spyder3 Elite will do the trick, you'll be able to generate a profile on your computer and load it on your tablet.
    As Android OS is not color-managed, the assumed target is sRGB: the default fallback.
    Thanks to that, the lack of color management at OS-level is not that bad, if your rendering device calibrated response just sticks with sRGB gamut and gamma curve.

    For years I'm trying to calibrate AMOLED displays and if I got some results (in my other project Display Expert) I'm still not much satisfied by the results yet, which is mostly why it never has been released yet
    And it's 3 years old now, with months and months of work on it ^^.

    AMOLED gamut is very large but panels chromaticity characteristics vary between samples and generations (but not as much as their response curve ^^)

  9. If I remember well, there is a project of cheap, open-source color calibration sensor tool.

    The problem with AMOLED is keeping the calibration right at all brightness levels, right?

    As Cyanogenmod is looking to improve the camera software (at least compared to stock AOSP), they may be interested (and become interesting for photographers – mobile makers often do weird postprocessing).

    That if, if Sony's detachable lenses don't solve the problem once and for all 🙂

  10. Well then. I got all excited for this to be able to tune my display to best possible output but i have no clue what kind of sensor is required or where i would get one…oh well keep up the great work supercurio.

  11. This is awesome!why?how many years android reviewer felt 720p was subparagraph when in fact reviewer were being lied to by android device maker since the screen couldn't 100% srgb,(yep oldest trick in the playbook.)it's sad,that's why I stopped buying android or any mobile device that can't prove it can do 100% srgb

  12. You are the man! I like to use my Nexus with Twomon, so that's really sweet!
    How can I keep updated about developments? Do you have a Google+ Beta Page? I searched, but couldn't find anything…

  13. Oh I didn't knew Twomon, although I can't use it with Linux it seems.
    Yes I created a G+ community but it has been inactive for a while as I was busy with other things.
    I'd say this Google+ profile is the best bet right now to follow this, although you might need to sort through personal posts as well.

  14. I'm just trying to calibrate it via i1Profile and Twomon. Still your App is useful when on the go etc! Maybe you could just write a comment here when there is some updates? I would get an notification then! Happy developing!

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