On Wed, May 18, 2016 at 9:03 AM, Richard Hughes <hughsient@xxxxxxxxx> wrote: > On 17 May 2016 at 22:33, Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: >> Settings > Power > Automatic brightness = On is the problem. > > This is probably my doing, I added the feature for F23 IIRC. > >> On my system it'll even go to the last setting and turn the >> display off as the room gets dark. > > So setting the panel to 0% is a bug that sounds like one that's > already fixed. What hardware is this? [ 0.000000] DMI: Apple Inc. MacBookPro8,2/Mac-94245A3940C91C80, BIOS MBP81.88Z.0047.B2C.1510261540 10/26/15 x-session info here: https://drive.google.com/open?id=0B_2Asp8DGjJ9T2U2VVQ0NUtNTW8 > >> It works better On than Off for daytime cloud fluctuations. But as the >> day transitions into night, the reduction in screen brightness is too >> aggressive. > > So this is where the "minimum configuration" in GNOME kinda hurts; > it's hard to pick an adaptive algorithm (or rather, coefficients for > an algorithm) that works for everyone. Well there's no way to know where the nit drop off is, as the backlight is lowered, without measuring it, is there? The backlight control looks like it works in 5% increments and on this display there's a pronounced drop off in brightness right at 20 to 15%, and again 15 to 10% and a huge one at 10 - 5%. There's a definite non-linearity at this low range. I don't know the threshold between software and hardware but I'd guess that the software is just sending the minimum increment/decrement value to the panel and we get what we get from the panel, i.e. thre is no such thing as 1% increments, at least for this panel. It's the same granularity in OS X so I expect it's fixed in the panel. If your hardware is supported, > can you turn off the support in g-c-c and install the "ColorHug > Backlight Utility" -- don't be scared of the name, it should support > other sensors as well. There you can tweak the numbers, although we > can't actually "set" them anywhere for GNOME to use. I'd be interested > in knowing what values you settle on for your hardware. Daytime: Ambient reports either 61 Lux - 43 Lux the whole day. At 58 Lux, backlight looks like 75% according to the graph. There's no raw value visible. And I'm not inclined to change the brightness. But even if it went up or down, chasing this narrow ambient range, I wouldn't notice it. I'll have to wait and see what happens as the terminator crosses my path, but I'm gonna guess that at some point the automatic setting is dropping brightness too much, given the panel's drop off behavior, too soon, and also goes too far. It's a noticeable drop off in the day time, at night when adaptation is mesopic and becoming scotopic, I'm more sensitive to these changes. So they seems more pronounced. Thing is, OS X doesn't get it right either, so I'm used to hitting a button to readjust it. It's just a different behavior in GNOME than OS X. I mean, I say "WTF psycho display" out loud no matter which OS I'm using. But yeah, between the display brightness drop off at the low end, and the human blob becoming more sensitive due to transitioning away from photopic adaptation, it's a fun little problem. And the thing is, I don't adapt at the same rate as the ambient changes. So the thing to chase at a certain ambient is an estimate of the user's adaptation, not the ambient. So the ambient goes down down down, keep brightness the same, ambient stabilizes, user adapts downward and becomes more sensitive so now the display needs to come down one notch and then a minute or 10 later, another notch even though ambient hasn't changed. And then there's the fact this light sensor in the laptop is under one of the speaker grills, so it's probably not a totally hideous way to approximate an integrating sphere? But... -- Chris Murphy -- test mailing list test@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe: http://lists.fedoraproject.org/admin/lists/test@xxxxxxxxxxxxxxxxxxxxxxx
