First off, I appreciate you going to this much trouble! I'm a bit confused, however; are you saying that with VGA output you get no eye strain? What are you outputting to? A regular VGA monitor? I found that my Macbook outputting to a VGA monitor gave the exact same eyestrain as to a DVI monitor (maybe a little bit less). As for the frame grabber, you can't necessarily assume that there is no feedback between the driver/video card and the monitor. A better test is to do a high-speed video recording (ideally 300 FPS or more) of the screen at high magnification and a "solid" color and see if the pixels flicker in a random or non-random way. I don't have access to a high-speed camera, but maybe someone on this list does.
Hi digisup, sorry for the late response! I don't have the green on black profile anymore, but here is how I created that profile:
- Download the program named SuperCal (you may find it easily with Google). It's a software that let you create a color profile by hand using your eye only. The free version is good enough.
- Use SuperCal to calibrate your monitor. However, when you're doing the calibrations, trick it by calibrating only the GREEN channel. For the RED and BLUE channel, pull all calibration points down to bottom (zero). After doing that correctly, you should get a profile that looks like black on green.
- Then go to the OSX Accessibility options, and check the boxes of "Invert Colors" and "Use grayscale"
By then, your screen should look pretty much like green on black monitor in the old days. Hope that helps!
No eye strain on VGA is only when I use the older 314.07 (Windows) NVidia driver. If I install newer driver (or use Linux + nouveau driver) then VGA is as bad as DVI, so I guess that only in that older driver version there is this difference between VGA and DVI.
As for my monitor, it is an older CCFL monitor with 6bit panel and I know the monitor reports 8bit to the GPU, so the monitor is doing its own dithering as well. Maybe it is even so that the monitor is "bad" and only when the GPU is coming with dithering on its side (the older driver with VGA input?) then I can use it. But all this dithering theory is becoming more and more adventurous...
Indeed a high quality, high speed camera would maybe better for investigation, it is that such camera costs probably over 10 thousands of $/€ or so... I have used a cheap high speed camera, but the image compression is so high that you cannot differentiate the pixels anymore. After I finish checking with frame grabber, I'll try again maybe with a better magnifying glass...
OK, just for fun I whipped together a little Python script to play around with dithering: http://pastebin.com/yL1EN07i. The program is terrible (lots of global variables, few comments) but it gets the job done. A couple of interesting things: looking at the program's output gives me eyestrain which is pretty similar to what I get from recent Apple monitors. Also, there are lots of different ways to do dithering; in this program I concentrated on random dithering, where each pixel independently chooses which of two states it's going to be in, or when each subpixel does the same. It turns out that pixel or subpixel makes little difference; you get snow either way. The only way to eliminate the snow and still have dithering (other than purely spatial dithering, which I didn't simulate) is to correlate the changes across all pixels. So my guess is that this kind of random dithering is similar to what we are seeing on our monitors and which is causing us eyestrain. It's simple to implement and does increase the number of perceivable colors, but at a great cost to some people.
I have found a new way to test the flicker. The old way is to take a photo of a vertical white line on black background with a DSLR and slow shutter speed. If the display flickers, then you will see many vertical lines, instead one wide white bar.
But according to that, iPad 1st generation does not flicker. However, last weekend at the summer cottage when my laptop was broken, I used my wife's iPad a lot. We also watched some movies from it. I started to get severe eye strain and watery eyes. My eyes are red and irritated even after 3 days have passed, after using iPad.
So I tested the display by setting my DSLR to video mode and Shutter speed to maximum 4000. When filming the display, it showed clear horizontal waves in the picture.
Then I tested my GS 2, GS 3 and Sony Xperia Z1 and filmed them together.
Gs3 had black stripes flowing = causes moderate eye strain
GS2 had barely visible to no black stripes = causes no eye strain
Z1 no stripes, waves or flickering at all = causes no eye strain
I have also set all monitors that I use to full backlight and tested them with DSLR to not flicker. Since I did that, I've got completely rid of the red eyes and intermittent/constant eye strain that I've had for years.
But once I used iPad for hours, the exact redness and eye strain came back.
I also tested my HP ZR2740w display by filming it with DSLR - it does not flicker or wave at all at any setting, and this is the display that I use the most. I have absolutely no eye strain, no matter if I browse the net and play games for hours.
If the display passes the 2 DSLR tests (Taking picture of the white line, Filming with shutter speed of 4000), then it does not cause eye strain.
I don't know what the filming shows, maybe it is the much talked about dithering, since some displays still show waves, though the backlight has been confirmed not to flicker by the 1st DSLR test.
I'd urge you to complete the same tests, with the displays that cause eye strain and the displays that do not.
But I have 3 devices that I have absolutely confirmed not to cause eye strain:
Samsung Galaxy S2 (when in full brightness)
Samsung SA850 (when full brightness)
Jury is still out there with the Surface Pro 2.
When screen brightness is set to full, it passes the both tests, but when not full, it fails the second test (visible waves are shown)
Difficult to say if it causes eye strain, since my eyes are still tired from the iPad.
F.lux makes no difference, so I do not believe that I'm at all sensitive to blue light or led light in general.
I think that for most people who have the same problem, the two DSLR tests would solve the problems completely, as it has done in my case.
Yes I can. I agree it is bright, but I've used it at work for about a year now with full brightness without any problems. I confirmed from my eye doctor, whether this could be harmful, but he said that absolutely not. If you think about it, if you are working out doors, you will get much more intense light levels than a bright display. The light will also be full spectrum.
First I reduced the brightness by software, but since that affects the contrast, I just now use it 100 % without problems.
I think the key to solving this problem is that first you replace all the displays that flicker (TV, Computer, Phone), let your eyes return to normal then you can start testing if some new display causes problems. I, for example, was unable to reliably say if a display was causing problems, when I had a phone, and TV that still flickered. It kinda th baseline irritation in the eyes, that your yes are constanty a bit strained by the flicker, what makes it imposible to say, if a new display you are trying is actually causing problems.
Or - then just test with a DSLR, which I'm sure that any person who is in the market for Apple products, can access one way or the other.
Hi everybody, I read the entire thread, massive.
I spent several days, as i didn't read all on a nutshell. I am on the same boat as you guys.
So my story: I bought an Samsung 27'' SA850D PLS. After one or two days, i started to feel pain on my eyes.
BTW I am not english native, so sorry for my flawed english, also i dont fully understand the exact term of eye-strain. Does strain relate to tireness, rigid? What i feel is real concrete pain.
I used the first day or two, the monitor with full brightness. Led's monitors are really bright at 100%, so i lowered the brightness, which made the pain lower when using it. But the harm was made. After I developed this eye-pain, i become photo-sensible, my eyes were hurt, and light make it harder for my eyes. Almost every kind of light except incandescent were not ok. My older TFT monitor also gave me pain, but to a less extend. My work computer, also TFT seemed to be uncomfortable to look at, where before i never notice it. But either way, the TFT monitors were still much better then the Samsung.
The pain was present for days, sometimes a little better, sometimes worse. I discover that sleep is really important. It helps or aggravate the sore on eyes. Meanhwhile i discovered flux, and turned my screen really red, which seemed to soft/alleviate the pain when using the monitor.
I spent on this pain process (eyes hurt) for about I don't know exactly, 3 months maybe. I went to 2 eye-doctors which told me i had a perfect sight. I could read the smallest letters. They seem to be clueless about this.
After this (3 months?) the pain disappeared or seem to be much less of a concern. My eyes get used to the monitor. My eyes didn't hurt looking at it.
I dont know if the pain was completely gone, or your brain adapts to it, sort like tinnitus.
I disabled flux, and just calibrated a little the RGB towards red, but not much. Months later I bought a HTC One, an amazing phone, and on the first days i felt some moderate pain. I lowered the brightness and my eyes get used to it. After 6 months my HTC One had a USB problem. I sent it to warranty. It came back with a new motherboard and a new screen. I dont understand why they change the screen. First i notice that the screen had a colder hue. More bluer. Also it seem 'better' looking, more sharper, i dont know. The thing is, this screen is killing me. It's crazy. It's killing my eyes. For a few days i felt my eyes hurting, but it got worse. My eyes are hurt again. Now after 1 second looking at this phone, is enough to feel like needles in my eyes. I am not as photo-sensitive as i wore on the first time i had this eye-soreness. Now when i reading a book, i feel my eyes hurt and sore, but when i look to my HTC one, it's really pain on the go. Now looking at my Samsung monitor is a between. Not as bad as the HTC One, far from it, but not as benign as reading a book with a incadescent light. My eyes are hurt.
HTC One screen's are not exactly the same: http://forum.xda-developers.com/showthread.php?t=2202869
I will post later more information on my HTC One screen.
typically if the strain has been severe, a couple of full nights of sleep and my eyes recover.
I tried to get my eyes adjusted to the PWM flicker also, but no chance. My eyes become so sore and red that I'm not able to even watch television. In the morning I wake up with the feeling that my eyeballs are swollen and dry. They are also red and I get comments if I have a hangover. So it is not possible to get used to the PWM flicker.
I have absolutely no photosensitivity or things of that nature. My eye sight is OK, though I do wear glasses sometimes on the computer, but most of the time not.
What is mind boggling is that e.g. we are watching a movie from the iPad with my wife - she has no problems, but my eyes get so red that she can clearly tell the difference. It's almost like an allergic reaction, which makes this whole thing even more strange. Also, no eye doctor admits that this problem exists. I did get a certificate from my PhD eye doctor, that I have this problem, but he just wrote it because I had red eyes and referred to some ergonimics of my workstation, so I can refer to that if I get a display at work that I cannot use.
So if it is psychosomatic like many would like to believe, it is a pretty strong psychosomatic reaction, as my eyes become noticeably red. There is no pain though. Irritation, sorenes, but no pain.
Also, as I've described in previous posts, I can do a ABX blind test, since the PWM is enabled by just setting the brightness to 99% in the Samsung display. And obviously, nobody can tell the difference of 99 and 100. Except my red eyes.
I dont usually have red eyes, but i have lots of pain.
When you say sore eyes but not pain, do you dont feel pain when watching? The sore is just an aftereffect like the eye being tired?
I am curious about the Sony Xperia Z1, it claims it uses a different technology then W-Led.
"Discover the widest colour spectrum ever offered on a smartphone display. Unique to Sony, TRILUMINOS Display technology creates incredibly true, natural shades of colours – just the way you want them."
TRILUMINOS Display technology (whatever that is) instead of conventional W-LED.
Maybe it's easier on eyes then the Blue-LED problem.
Perhaps the technology is similar to the QDEF described here:
Can you check if Z1 has PWM for medium and low brightness? Can you also make the photo test? I would really appreciate it. Maybe i would test it, and replace the HTC One.
I tested the z1, no flicker under any circumstances.
I do no have acces to a mac. Only an iPad. But like I pointed out, Im not sensitive to the blue light it is the flicker that was visible in the dslr test. Thus it would not make sense to test the grayscale. I feel that many people insist that it is the blue light or ligh spectrum, without even testing to have all displays without flicker. If you are sensitive to the flicker, no amount of grayscaling or setting the colours to green an black will help the situation. And if you have a device with flickering screen that u use a lot, you will never find out if it is the flicker or something else. Then there are the people with head injuries and rare syndromas - these cases, while unfortunate to the individual, do not represent the general 'population' that are sensitive to the flicker.