Exactly why do you need root for Flux Android?

  • Here's what I can't find any info on. Why do you need root on Android?

    On that note, why do you also need jailbreak on Apple devices?

    Reason for asking is, there are non-root apps out there (for Android) that can make the screen more red and less blue by using "draw over other apps" technique. While not perfect (I would love for it to NOT seep into screenshots; and some toasts appear on TOP of the orange layer), it works great and makes my Android phone screen easier to look at during night.

    What does f.lux do differently that it requires root access to function?

  • So the short answer is that we don't use the overlay technique because adding pink isn't the same as removing blue.

    "Works great" is subjective, you can see measurements for one overlay app here: https://fluxometer.com/rainbow/#!id=Nexus 4 Apps/6500k-nexus4

  • @lorna Then what do you do? Mind explaining how exactly you remove blue on a rooted Android phone?

  • @agent007bond we change every color on screen to remove blue and green light while mostly maintaining color perception. You might like reading up about https://en.wikipedia.org/wiki/Color_constancy and https://en.wikipedia.org/wiki/Chromatic_adaptation too. I'm not sure how much detail you want, but effectively mobile phones don't have accessible color management like desktops do, so we need access at a lower level. So that's the reason for needing root (and additionally on iPhones, it's needed because otherwise apps cannot run in the background).

  • Does it mean that even a definitive version (non preview) of f.lux will always need root access ? and so that there will never be a non-root app allowing to really remove blue and green light (not a simple overlay) ?


  • @ddmflux153 For older operating systems that will probably be true, but we expect it to be possible in future updates.

  • @lorna I did the color constancy test. Square A is DEFINITELY darker than square B. Until I put B next to square A. I think our eyes are too easily fooled, maybe it's a good thing?

    I also zoomed WAY into the square b (the "lighter" square in the "shade") and put it RIGHT NEXT to the same square in the picture. In the original picture, square B STILL LOOKS LIGHTER! That's absolutely insane!

  • Another very big disadvantage of "draw-on-top" method is that it greatly reduces contrast, what results in dramatically impaled readability and sometimes causes even more eyestrain than 'default' blue light.

  • @lorna Im sure you've been using android n, any chance this is the update that will allow f.lux to be a 'without root' application? I'm Not sold by the other alternatives out there.

  • @LipReader I seriously doubt this app will ever be non-root. Not in the foreseeable future for sure.

    Why not just root your phone? If I could do it, so can you. I suggest you look in CyanogenMod Wiki for detailed instructions on how to root your phone, if you follow it step-by-step nothing can go wrong.

    And if your phone is not supported by CM, there are plenty other detailed step-by-step guides out there you can easily Google.

  • @pureby It's not that easy with locked bootloaders, and some versions 4.4.4 and 5.0 not having root on certain carriers. Example, Note 3 Verizon, got back down to 4.4.4, and it's HAMMERING ME to update. That's what I hate about android, the carriers can literally force you to upgrade, or try to. On 4.4.3, I could say "not now" and it would leave me alone, but on up, that's not an option, it's either now or later.

    I have to disable SDM with an ADB tool to stop it from loading the update question. Find me a root method for Note 3 Verizon, on 4.4.4 (preferably) or 5.0. The later has annoying issues, like SEVERELY complicating access to "Emergency Call" on the lock screen, and it's the update that DESTROYED (HALVED or more) my battery life. I'm slowing fixing it finally, but it's tedious.

  • @pureby I know how to root and have done it before, but I have certain applications that will not work with root, and I'm not planning on sacrificing them for f.lux when theres applications out there who dont do the same but are close enough. I will gladly wait...

  • @LipReader Best you can do for sleep without rooting is to dim your screen all the way and hold it far away from your eyes - the tinted overlays leave a lot of alerting light in and prevent your screen from being readable when dimmed all the way. Hope we have a better option for you soon.

  • @LipReader The non-root alternatives to f.lux or CF.lumen aren't "close enough" - they don't work at all the way rooted apps do.

  • I just got the Android 7.0 Preview for my Nexus 6P. Is it safe to root my phone for f.lux on Nougat??

  • @Tungsten_smooth Assuming you haven't found it yet, there is root on the VZW Note 3 on 5.0 (not for 4.4.4 that I know of). There's also a bootloader unlock available, letting you install TWRP and flash custom ROMs. I had CM13 (Android 6.0.1) running on my VZW Note 3 before the screen broke. Check out XDA for more info.

  • @amorrn Thanks, I'll look into this! Maybe I'll keep the phone if I can root it, and I just need a new battery for it, maybe I'll get an extended battery. I need a phone that doesn't use PWM like OLED screens do though, so I might switch up to something like an LG G5 or a droid maxx 2.

  • @lorna My friend would like a full technical explanation with details of what you're trying to accomplish with f.lux, especially on an LCD screen.

    In his words:
    so i don't get it
    how does it work on iphone?
    you can't just turn off blue on a non amoled screen
    the backlight of all LCD displays is a big white light
    yea i'm saying that's not possible with LCD
    you can't just remove a spectrum
    and still maintain any modicum of color perception

    yea so it just shifts the color balance
    doesn't really get rid of blues
    in theory sure
    that's for overlays
    you can't remove blue light on an LCD
    you can only block it or filter it with the pixels
    so it just uses a stronger red filter and a darker filter on the blue
    it still has blue light in the end
    otherwise you wouldn't have a lot of colors coming through
    it would look retarded
    so what i'm saying is you could simply reduce brightness for a similar effect
    i think it's mainly psychological to you

  • @THE_Roen Tell your friend to ask Apple why they introduced night shift as an official baked in feature for iPhones then. They have LCD screens and it does work.

  • @THE_Roen It turns out all these things you're asking about can be measured and so we did. We've used reference grade gear to take some measurements of different screens and we've put it up online for everyone to use, along with the most recent science we know about in the subject.

    Remember there are many variables, like viewing distance from the eye to the screen, age of the viewer, and even personal sensitivity, but you can play around with some of that in the models here: https://fluxometer.com

    Reducing brightness all the way definitely helps, but there's likely more going on that that - color shift have shown some very interesting effects. It's all an active area of research.

    I hope this information gets you started on what I think is the most interesting area of research. Please encourage your friend to write us with any questions directly, too.

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  • @lorna I have an Essential Phone Android Phone. The latest update included Android 9.0 Oreo and it added a built in blue light filter in the settings.

    I have a few other phones (3 more) that also have a built in blue light filter. Ironically, my ZTE Axon 7 has the best blue filter. When you compare all of my Phones (4) blue filters, the Axon 7 has the darkest most pronounced “Orange Tint.”

    My point and My question is if I have the built in blue filter turned on to the max and install a non-root required Blue Light filter App, to reduce the blue light EVEN MORE, will that work?

    I don’t want to root my Essential Phone in order to install the F.lux app because of the security risks associated with rooting.

    I have however rooted previous phones and installed F.lux and loved it big time.


    Larry Martin

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