Twilight and Lux both contain naive implementations using a semitransparent overlay. The result of this that blacks and dark colors end up being <i>brightened</i> instead of left alone, as a proper color-temperature change would do. This looks bad on all screens, but especially so on AMOLED displays that support a true black.<p>Cf.lumen[1] is, I believe, the only Android app that can actually change the color temperature of the screen like f.lux can, but it requires root as well as installation of a special &quot;driver&quot; in order to do so. My guess would be that the &quot;complicated install process&quot; referenced by the f.lux devs is probably similar.<p>[1] <a href="https:&#x2F;&#x2F;play.google.com&#x2F;store&#x2F;apps&#x2F;details?id=eu.chainfire.lumen&amp;hl=en" rel="nofollow">https:&#x2F;&#x2F;play.google.com&#x2F;store&#x2F;apps&#x2F;details?id=eu.chainfire.l...</a>