Hi mojarvinen, do you still have access to the S4 phones?
Would you be able to try the method that I described in page 75 and see if that helps?
Putting my Note 2's AMOLED screen to max brightness and then controlling the brightness by using 3rd party software (an app named "Screen Filter" in my case) appears to be able to almost eliminate flickering on my screen.
After short try, it just reduces the brightness of the screen, just like the Androind's own brightness controll. I could verify this by measuring the flickering rate, but my eyes seemed to confirm this in couple of seconds... so. I don't think that a software can affect the way the AMOLED pixels are dimmed. Those are always dimmed by PWM flickering.
It's incredible how frustrating this is. My GS3 was usable when 100% but after say 1,5 hours reading a book or browsing the net, eyes started to hurt. GS4 is a bit worse.
Otherwise, now that I have the HP Zr2740W display at home, which is confirmed not to flicker and also a flicker free display at work, if I don't use the phone that much, my eyes are completely irritation free. I wish there just would be a phone that would not have PWM flicker... I have high hopes for the Sony Z1 or the LG G2.
Wonder how long does it take for manufacturers to realize this? It must be a rather large percentage of people who are suffering with this problem, since some manufacturers are already advertizing flicker free displays. I guess it's just that not that many peopl use phones for that long. But well - I do, on the weekends when at the summer cottage, I use for navigation while fishing - then I read e-mails, browse the net etc. So it's not like I would be some heavyuser that just stares at a small screen too much.
The tool is DSLR. Make a picture with (e.g. MS Paint) with black background. Draw a couple of pixels - couple of millimeters wide vertical line into the middle. Set your DSLR to manual and select shutter speed to 1/8 for example.
Take a picture so that during the open shutter you slide the camera horizontally slowly. If the display does not flicker, you will see a wide white bar in the picture. If it flickers, you will see multiple bars. If the shutter speed is 1/8 seconds, then you calculate the number of bars you see in the picture an multiply it by 8. = the Hz value of the flickering.
By the way, speaking from my experience on the Note 2. Setting the brightness to max while disabling auto brightness + dimming with the "Screen Filter" app only help with the flickering.
And other than flickering, that screen also has the problem of blue light, which, switching the screen mode from "Standard" to "Natural" or "Movie" helps a bit as that two modes reduces the strong saturation of the default setting.
Please be sure to try out this setting too if anyone wants to test the screen for comfortability in the future.
I have also tested lumia 920. I have seen there is an option to control color saturation and temperature. For color saturation someone can enter in a climax between natural and vivid, i guess the natural would be the more eye friendly.
For temp there a climax between warm and cool. When the i choose the warm option the screen becomes a bit yellow. I would expect the warm option to be the more eye friendly but it seems to make me more dizzy than having the display in the cool mode (the display becomes something of a grey/blue), something that i find strange. Wouldn't a yellow display color block more of the blue light? Brightness is set to high (the highest degree).
I would like to stress, that it is not the colour temperature that causes the eye irritation. It is the Pulse Width Modulation backlight flicker that happens on 240 Hz. In the case of AMOLED it is not backlight, but individual pixel flicker. Why I know? Beckause I happen to have glasses that block all blue light (real, industrial grade blue light blocking glasses) and trying with those does not help at all. Also, reducing the brighness, increases the irritation. This is not something that I think, it is fact that I've tried since HTC Desire HD and after that several phones and for the past 15 years with tens of LCD displays. I'm stressing this because when ever someone on this thread mentions the PWM flicker - a proven cause of eye irritation - there is always someone who starts suggesting colour temperatures and turning down the back light. The people who are affected by the PWM flicker, there is no other way to fix the problem than stop the PWM flicker. Either by getting a display that does not flicker, or by not looking at a display that flicker. Also - the flicker is not visible by the eye, a 240 Hz flicker cannot be detected by human eye, only the optic nerve registers it. It is not like a strobo light, which is flickering something like 30 Hz.
The thing, Mojarvinen, is that it isn't JUST the PWM that is a problem here. It is for you, absolutely. But honestly I am not THAT sensitive to PWM. CCFL's with PWM aren't USUALLY a problem for me unless the PWM is really bad, and first-gen LED's with PWM aren't a problem for me either (again, unless the PWM is especially egregious). The Thinkpad X220 that I do 90% of my work on and look at for 6+ hours daily has fairly obvious PWM (easily observable by the finger wiggle test) and yet I have no issues with it. The Macbook Pro Retina has much less PWM, and there is NO way to make that display acceptable for me. Maybe the higher the PWM the worse it is for me? Like 60hz or 120hz PWM is fine, but 480hz isn't? I don't know. But newer X220's with supposedly IDENTICAL displays are painful for me to look at, and the ONLY difference is that the type of LED being used (according to Lenovo) is a "whiter" (read: bluer) LED panel. Maybe they're lying and it also has worse (for me) PWM? I can't say.
All I know is that PWM is not the ONLY problem, or that it isn't as simple as just saying "it has PWM therefore..."
For the record, I can use the following displays with NO problem:
Macbook Pro 2008-2010 (LED backlit, with PWM)
HP 23-inch monitor (LED backlit, with PWM)
Lenovo X220 first-batch (LED backlit, with DRASTIC PWM)
iPhone 3, iPhone 4, iPhone 4s (the 4s gave me SOME trouble for a while but only after lengthy exposure)
iPad 1, iPad 2
Dell 2409 (CCFL, natch)
I cannot use the following displays:
Macbook Pro 2010-2012 (non-retina, still LED backlit, supposedly less PWM than the older models)
Macbook Pro Retina 2012-2013
HP 30-inch monitor
Lenovo X220 second-batch (newer screen, still LED backlit, same amount of PWM)
Galaxy S4, Nokia Lumia 920/928
iPad 3 and newer
Dell 2412 (LED, known terrible)
As you can see, I have NO problem with some PWM and some LED. But the newer the LED, the more likely I am to not be able to tolerate it. And the newer ones are supposedly "flicker free", which probably just means that the PWM has been moved to a higher frequency...
The Retina displays have individual pixel flicker, too. I don't know if it's temporal dithering or what, but if I look very closely I can see the pixels dance...
Yes, I agree with you. There seems to be some people that are sensitive to blue light and also some other problems.
But what you are saying is that you have problem with some displays that have PWM but with some you don't.
I don't see how this is in dispute what I said? I also had a Samsung CCFL display with PWM, which I had minor problems. But the PWM was 130 Hz and as CCFL light dims instead of goes immediatly dark, it is easier on the eyes.
And yes, there might be PWM's with 480 Hz or more, that do not cause problems.
The White LED might cause a problem, because there is more intense ligth at some blue part of the spectrum and then when that is flickered, it irritates the eye, but it is still the PWM flicker that is causing the problem, not the white led as such. I'm not sure, but I would think that if you'd just look at a white led that does not flicker, that would not cause problems.
What I said is that if one has problems with certain PWM frequency, changing the colour temperature, brightness or anything like that will not help. (Well, in the case of 100 % brightness, many LCD displays do not flicker)
There is additionally the pixel flicker/pixel dance/snowing/dithering -problem. I personally don't know about that, but I suspect that also in that case, no colour temperature or brightness setting will help.
My general point is that it is frustrating that people that don't seem to suffer with this problem tend to suggest things that don't really help at all. Since we both have clearly, with several others in this thread, identified that PWM at a certain frequency can be a problem, let's advertize that to all who come in and complain about the problem.
I mean - there was the discussion about head injury. Valuable discussion no doubt. Yes, that might be one cause for some people, but as PWM is absolutely and clearly a problem for, I'd say most, then it I'd see it as most helpfull to those to point out - get a PWM free display and do not fiddle with colour temperatures with your eyes red for months. It's so simple. Of course, if that person then happens to also suffer from dithering or blue light, then that's another thing.
Oh, absolutely. I think there are at least TWO separate problems.
For example, LED street signs and car tail lights are a MAJOR problem for me. That has nothing to do with PWM - it seems they don't dim those AT ALL - and everything to do with intensity/spectrum.
But yes, the problem for a large number of people is PWM, and switching to a Dell 2410 (expensive) or 2409 (less expensive) will probably resolve a vast majority of people's issues.
We had one guy in here who disassemlbed his TV and overrode the PWM module, put in a filter for the blue light, and is totally happy now. I think he should get a job working for Samsung.