Thursday, July 13, 2017

Screen that hurts my eyes, take 2

Six month ago, I wrote a lengthy post about my new computer hurting my eyes. I haven't made any progress with that, but I've accidentally upgraded my work computer from Kernel 4.4 to 4.8 and the nvidia drivers from 340.96-4 to 375.66-2. Well, my work computer now hurts, I've switched back to the previous kernel and drivers, I hope it'll be back to normal.

Any ideas of something specific that changed, either between 4.4 and 4.8 (kernel startup code, default framebuffer modes, etc ?), or between the 340.96 and the 375.66 drivers ? In any case, I'll try that specific combination of kernels/drivers home to see if I can get it to a useable state.

Update, July 23rd

I reverted to the earlier drivers/kernel, to no avail. But it seems in fact the problem with my work computer is linked to an allergy of some kind, since antihistamine drugs have an effect (there are construction works in my lab, perhaps they are the cause ?). No idea still for my home computer, for which the problem is definitely not solved.


Nathaniel Kipps said...

Seems like a long shot, but maybe it's a super-high frequency sound? Maybe try sitting next to it while it's running (and screen is on), but not looking at it (reading a book or something).

Chris Hamilton said...

I am sensitive to flickering in monitors. This was largely gone after the transition to LCD monitors from CRT. Recently some LCD monitors use an LED backlight with a PWM circuit that gives me headaches. Other ( presumably higher quality ) LED backlit LCD monitors don't bother me.

Something that could be controlled by software updates on your end is the digital brightness adjustment. This brightness control is sent by the video card to the monitor over the DVI or HDMI cable. Some monitors produce a steady backlight at full brightness but begin to flicker as the brightness level is decreased.

Depending on the speed of the flickering it should be possible to detect using a high frame rate camera or by placing something like a running electric fan in front of the monitor.

Another possible issue is that the chroma subsampling settings could be altered. I would suggest reading the wikipedia page on chroma subsampling and then trying to figure out if you have somehow ended up at any setting less than 4:4:4. The wikipedia page has good examples of how images can be subtly altered by chroma subsampling. There are free test patterns online that will help determine if it is happening.

Vincent Fourmond said...

@Chris This looks like helpful advice, I hadn't thought about using a fan, but this looks like something I should try, thanks !

@Nathaniel As far as I can tell, I have no problems with screens off: in situations where my eyes start instantly to ache, switching off the screen stops the pain. Thanks !

Julian said...

Have you tried using the 'redshift' or 'redshift-gtk' (frontend) packages? They could help fix the problem, although not very helpful if you do color sensitive work.

Peter C said...

Welcome to the rabbit hole of manufacturers making displays harder for people to look at. The motivation is to reduce power consumption, or to allow for cheaper manufacturing cost.

Try adding this line to your xorg.conf file on the computer with the Nvidia card to see if it helps.

Options "FlatPanelProperties" "Dithering = Disabled"

Josh Triplett said...

> @Nathaniel As far as I can tell, I have no problems with screens off: in situations where my eyes start instantly to ache, switching off the screen stops the pain. Thanks !

That wasn't the suggested test. Leave the monitor on, sit next to it, and don't look at it. That would distinguish between a visual issue and an audible issue. I've had equipment that generated headache-inducing audio.

Vincent Fourmond said...

@Josh Hmmm, point well taken. Leaving it on and not really looking doesn't quite work, you alway look to some extent (and I know it hurts). I should try leaving it on and covering with black cloth or something, good idea !