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  • jongmini Level 1 Level 1 (0 points)

    mvanier, I am definitely no expert when it comes to liquid crystal modules, but in my knowledge, using the liquid crystal orientation to reduce brightness does not affect your ability to render color, since the color filter is on top of the liquid crystal.

  • Jessiah1 Level 1 Level 1 (0 points)

    "Jesse, I wouldn't worry about the effect of the 60 Hz power supply on the monitor.  For one thing, most of us use laptops regularly that aren't even plugged in, and we still get eyestrain symptoms from this."


    Are there "Flicker free" laptop? As I understand it these are guaranteed to have PWM or something like it to save on energy consumption when not plugged in?


    Just to be clear on my input about the effects power delivery could have on LED lights of any kind. When I read about the response time of an LED light compared to say fluorescent and then incandescent( obviously the slowest to turn on or off because of glowing hot metal) it seems that even the slightest variances may be detectable by eye with LED. If you listen closely as everyone speaks about their individual symptoms you hear that some can tolerate everything except LED and some are slightly sensitive to CCFL and then some are very sensitive to both. Everyone's symptoms clearly show a pattern of LED being the most intense even though it is running off the same hardware, power delivery, dithering, software and on and on. Both lighting technologies are sometimes running off exactly the same platform and yet LED is so much worse for everyone. Some cannot tolerate LED but have 0 issues with CCFL, unfortunately I hate them both however CCFL is definitely not as bad for me. When you read about fluorescent lighting it becomes obvious this technology cannot power on/off even 50% of the level LED's can, I am of course using a hypothetical % here. But Fluorescent leaves "ghost" light behind just like an incandescent due to a glowing after effect from the gasses. So, do we really know for sure what we can detect from LED's when they seem to be so much more responsive to variances than any other light source?


    When whole rooms are lit by solid state lighting I want to gouge my eyes out to get away from the effects, it's disorienting, what I am seeing that average people are oblivious to? It can't be dithering or software platforms.... And I am not the only one here, I believe many here have not had the pleasure of 100% LED solid state lighting enviroments as of yet depending on their location in this world.


    "It is not theoretically impossible for a monitor to have some interference from a 60 Hz power source but this is something the industry is well aware of and has dealt with over the course of decades."


    LED backlighting has not been a prominent technology until recently so IMO old school methods could be causing new school problems.


    As for people "not having had success with flicker-free monitors", I wasn't aware of that. 


    There are a few comments on this further back before the person who got the wrong monitor however I am just going off memory and cannot recall who stated this...If I recall correctly it was one or two experiences with BenQ monitors. I am very interested in trying one because there is not one LED device I can tolerate and I am wondering if flicker is removed will there be improvement?


    I appreciate all of your inputs and time responding Mvanier, I hope it is understood that I am challenging your knowledge with questions so I (and whoever else cares about the same questions) can get a better understanding. I am not a software engineer nor a PHD, I have however read my eyes out for 2 years now and that's where my theories and questions come from which as you can tell I have many. This forum happens to be the best place on the web to discuss this as well.




  • tight_eye Level 1 Level 1 (0 points)

    Hey guys, today I found out something really interesting. I actually own two Macbooks, first on the right side the 2012 MBP standard configuration, left hand side the brand new rMBP 13' late 13. Someone mentioned, that the rMBP has a reddish oder brownish tint to it's display and today I discovered that this is not due to different backlighting but due to different display manufacturings. Remember the MBP has the glass panel in front of the screen and the rMBPs screen is straightly glued to the front panel so that both is one unit actually.


    Both computers are turned off and positioned in front of my rooms window. No flash used. Only daylight. What can we see? Right Display shows neutral colours and left display is darker and red.

    This amazed me so much that I had to share this image.


  • Jessiah1 Level 1 Level 1 (0 points)

    Very interesting tight eye, what do you suppose the red tint is from, does anyone know? Polarized or something else?



  • tight_eye Level 1 Level 1 (0 points)

    Well the first thing coming to my mind when I saw this was polarization. But it is completely new to me that this technique automatically causes this ridicolous red cast.

  • StefanD13 Level 1 Level 1 (0 points)

    Hi mvanier,

    Yes, casio exilim ex-fs10, quite cheap and also very low picture quality (due to compression) when recording at high speed. I could distinguish pixels only whe filming my ccfl monitor. With notebooks the camera quality is not enough, the pixels are too small to distinguish.

    Anyway I can see that my old ccfl (benq) does temp dithering which seems not to bother me...

    In the mean time I followed your example and tried also a notebook with no (at least measurable) pwm and intel graphics with linux and eye strain still present no matter if spatial or no dithering at all.

    So currently I'm in the process of accepting that it could be something else, only I have no clue.

    By the way, did you try drm.debug=0x06 as a kernel boot parameter? You can get interesting details in the kernel log (dmesg | grep drm). Although it didn't get me any new idea, maybe it does for you...


  • mvanier Level 1 Level 1 (0 points)



    Thanks for the tip about drm.debug (I haven't tried that yet).  I've been playing around with a bunch of stuff.  I found out that both Ubuntu and Mac OS X have eyestrain issues on my new MacBook, but different ones.  For Mac OS X it's just the "snow" (dithering?) and apparently nothing else.  Ubuntu doesn't have the snow but it has something else, which I think is just PWM.  What really surprised me is when I connected the Macbook/Ubuntu to my old CCFL-backlit monitor, then I noticed some eyestrain from PWM which was greatly reduced when I turned to monitor to full brightness (but then it's too bright to use comfortably for long).  This amazed me because I'd assumed that PWM was not a problem on CCFL-backlit monitors.  It turns out that this may not always be the case.  Somehow, the Mac drivers are driving the PWM in a "softer" way than Ubuntu is on the external monitor (which may not be surprising, since it's an Apple monitor).  I also measured the PWM frequency crudely using a camera test, and found no difference between Mac and Ubuntu.  If I use the built-in panel with Mac/Ubuntu, then there doesn't seem to be PWM, but there is a lot of blue light.  So my setup seems to produce every possible kind of eyestrain-producing effect!  Unfortunately I don't yet have a way to get rid of the eyestrain completely.  I'm thinking of ordering a Dell U2413 monitor, because that has no PWM at > 20% brightness and very high frequency PWM below.  That should in theory work well with Ubuntu, but perhaps not as well with Mac OS.


    I've also found out something else.  Over time, I'm getting less sensitive to the "snow" effect on Mac OS, to the point that I can use the computer for (say) an hour without it being too bad.  I think my brain is learning to tune out the snow, which presumably results in less eyestrain.  I have no idea if I'll eventually be able to use the computer for long periods of time, but this is at least a little bit encouraging.  I've also found out that Mac OS X Mavericks has pretty much removed everything I liked in Snow Leopard and replaced it with stuff I don't like, but that is a rant for another mailing list

  • tight_eye Level 1 Level 1 (0 points)

    Actually sitting in front of the rMBP late 2013. Also very painful to work with but this is truely the best machine available on the market. Perfect in any means. BUT there is snow everywhere. Looking onto this page gives me severe eye strain. I use the computer for work and have to read and write a lot. So this is nearly killing me.


    After a few days with the regular MBP I noticed it got a bit better, but now with the retina it's imo even worse compared to the MBP. I showed the laptop to my parents. Neither my father nor my mother could tell they get eye strain. They see no snow and think the screen is perfect. Wish I could change my eyes with them. Now I'm thinking again that I've got hallucinations. I'm feeling so sad.


    In fact I just cannot blame only Apple for this because I had the same problems with the last Lenovo Laptop I owned for a short while (Lenovo Thinkpad Yoga).

  • tight_eye Level 1 Level 1 (0 points)

    Crazy, thanks for the links. Then this is not what I just specified to be snow on the screen. To me all whites on the macbook screens appear absolutely disturbing like pulsating around and around. My eyes are not able to stare at written letters and words. Don't know how to describe it better.

  • TheSunshyn Level 1 Level 1 (0 points)

    I got one of the new BenQ flicker-free monitors last summer because I had been unable to find any monitor for years which did not cause headaches. The flicker-free one really helps me and is a huge relief.


    In addition to the business PC I had on the monitor, I'd been using a late 2009 MBP with no headache problems at all. When I tried to replace it with a different laptop, I ran into the headache problems all over again so I just managed to save up enough money for a new MBP (Oct '13).  Its wonderful for my eyesight if I'm using it with no dimming, but I had a migraine last night after using it with some dimming so it really does seem like my problem is with PWM, despite how rare that sensitivity is supposed to be. I downloaded Shades but am holding off testing it with dimming until I shake the remainders of this migraine.

  • mvanier Level 1 Level 1 (0 points)

    @tight_eye: it's OK, you described it well enough.  You're not crazy, I see the exact same thing and many of us here do too.  It's probably caused by temporal dithering, but don't expect Apple to ever do anything about it since it's been there for several years (also in all iPads I've seen recently, but curiously not in iPhones).   The good news is that over time some people (apparently including me) can get used to it to a considerable degree.  Yesterday I used my Macbook (with Mac OS X, not the Ubuntu partition) for several hours and even though it was uncomfortable it was never unbearable.  The brain can learn to tune out the noise (that's one thing brains are very good at).  Using my new Dell U2410 monitor also helped a lot compared to my old Apple Cinema display, probably just because the old display is... old. 


    One thing you might look into is a monitor which refreshes at 120Hz or more.  Even though the dithering would still be there, it would probably be at twice the speed so you might not see it.  BenQ makes some 120+ Hz monitors, some of which are also flicker-free.  The downside is that most of them also do hardware dithering due to 6-bit color TN panels (which are the fastest), but again, it probably would be so fast you wouldn't notice it.


    PWM, I suspect, is another matter.  Since the flicker is so regular, I wouldn't be surprised if it's something you can never "get used to".  The good news is that more and more monitors are coming out that are PWM-free.

  • tight_eye Level 1 Level 1 (0 points)

    @mvanier: Thanks for your reply, it makes me feel I'm not alone, though there keeps a fair amount of sadness to this whole situation. For me a laptop is the base for all money I earn, so this is very critical.

    What makes me wonder is that I can work with my old Vaio VPCY11S1E/S without any complaints. From my understanding it also uses dithering and well it is a LED display too.

    Then I have a very good external monitor, it is a BenQ FP91 GX. The model was relatively expensive when it came out years ago. The resolution is not up to date compared to todays level but I can look at this peace the whole day und never get worn eyes. Again this is LED too. Dithering I don't know, I'm not really familiar with this effect and didn't find too much information about it on the web.


    What I'm additionally interested in: I discovered that the problematic effect is less pronounced when I tilt the screen down ur up and look at it at a very sharp angle. I figure out less light hitting my eyes hard and it is a bit more comfort to it. Don't know what to think about this.

  • mvanier Level 1 Level 1 (0 points)

    @tight_eye: Dithering is a way to simulate colors on a display that can't actually produce those colors.  A crude example would be a display that could produce only red, green, and blue but nothing else.  If you flash red and blue back and forth the resulting color might look like purple (or not, but let's say it does).  That's dithering, or more specifically, it's temporal dithering.  There are many different dithering algorithms, though, and some of them are "spatiotemporal dithering" where they change the colors of several neighboring pixels at 60 Hz to simulate colors the monitor can't actually produce.  This could easily produce a "snow" effect.  Worse, some computers do this even when hooked up to monitors that can produce those colors.  I think this is what Apple does.  I'm pretty sure that Linux running on Intel graphics chips doesn't use temporal dithering if that is an option for you, but Apple seems to be in love with dithering.  You should definitely look into 120Hz monitors (as should I, if I could ever find one; my local Fry's is basically worthless for high-end monitors).

  • tight_eye Level 1 Level 1 (0 points)

    Sorry, I meant piece, not peace*