1 96 97 98 99 100 Previous Next 2,032 Replies Latest reply: Jun 26, 2014 8:34 AM by luisx Go to original post Branched to a new discussion.
  • 1,455. Re: Eye strain from LED backlighting in MacBook Pro
    kvoth Level 1 Level 1 (0 points)

    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.

    First, grayscale is more than about spectrum. By grayscaling, you get less dithering. Dithering forces flicker.

     

    Second, with regards to your comments about flicker vs. spectrum, they are INTERRELATED. People complaining about flicker and people that complain about spectrum are both right.

     

    New LED lights have "perfect on/perfect off". The light that hits our eyes appears to be fully on or fully off -- a square wave of light. Light does not travel in square waves, it travels in sine waves. BUT, by combining multiple frequencies of light with the correct timing, a square wave can be created by the HARMONICS.

     

    Read about a square wave here: http://en.wikipedia.org/wiki/Square_wave

     

    In the lights that we use that are creating these square waves, guess what frequency of light is in there?

     

    SO, if you are bothered by a light source that has a "perfect" flicker, like new LEDs, you are simultaneously experiencing ultraviolet frequency light AND the flicker.

     

    This is why this glasses coating, Crial Prevencia, mitigates our issues. It filters ultraviolet light, which simultaneously solves flicker and spectrum issues.

    http://www.crizalusa.com/Crizal-Lenses/Crizal-Prevencia/Pages/default.aspx

     

    WHEW. Long story short: Dithering causes flicker. Grayscale can get rid of dithering. Could you give grayscale a shot and report back? It's working TREMENDOUSLY for me.

  • 1,456. Re: Eye strain from LED backlighting in MacBook Pro
    tfouto Level 1 Level 1 (0 points)

    As i said before there are different screens manufacters for the HTC One.

     

    http://forum.xda-developers.com/showthread.php?t=2202869

     

    In this image below, this are not my phones, but the image fullfils the purpose:

     

    https://dl.dropboxusercontent.com/u/548546/IMG_0028.JPG

     

    My second screen is similar to the right one, cooler. One thing i notice is the rainbow effect. It's much more prounanced on the second one. I notice on my new screen but never on the old one. You'll see below later what i am talking about...

       

    My screen:

     

    m7_panel_init panel ID = PANEL_ID_M7_SHARP_RENESAS_CMD

    m7_panel_init: PWM IC version A2

     

    I dont know if the PWM it's about Pulse-width-modulation, so i just wanted to check. First i tried with shutter speeds of 1/25 and 1/8. Nothing all smooth.

     

    So i tried 1 second, even if it didn't make any sense, and to my utter suprise i found this:

    low brightness

     

    http://imageshack.us/a/img43/6748/rt7k.jpg

    http://imageshack.us/a/img843/1034/48j8.jpg

     

    this not make any sense... i count 10 lines. This means PWM of 10hz?????

     

    This is really weird... Shouldn't i notice on naked eye?

     

    Then i tried full brightness:

     

    http://imageshack.us/a/img209/5106/5epd.jpg

     

    In this photo i had a higher ISO so, it's more smooth:

     

    http://imageshack.us/a/img10/9291/p6pm.jpg

     

    you can see near the top some colours... just a curiosity...

     

    This PWM is really strange... around 10Hz. altough i dont understand if the light fully stops or not.

     

    What puzzle's me it's the led's on the bottom of the phone also appear to have this frequency, so maybe it's just me, who's just doing something wrong.

     

     

    Now in this 2 pictures:

     

     

    http://imageshack.us/a/img854/6109/bhmi.jpg

    http://imageshack.us/a/img801/2758/b5x3.jpg

     

    you could see the polorised effect, but with colors. Live it's much more visible then on photo. If put the glasses and watch my monitor 27'' LED i just see white or black as i move my head... but on the phone it's full of rainbow colours...

  • 1,457. Re: Eye strain from LED backlighting in MacBook Pro
    tfouto Level 1 Level 1 (0 points)

    What is helping you tremendously? the glasses and greyscale? How do you make it greyscale?

  • 1,458. Re: Eye strain from LED backlighting in MacBook Pro
    mvanier Level 1 Level 1 (0 points)

    I'm very glad that you've gotten significant relief of your symptoms by switching to grayscale.  It didn't work for me, but whatever works for you is good for you.  On the other hand, do you want to be restricted to grayscale for all of your computing?  If that were the case, I would start to look for alternatives to Apple.  Also, I disagree with your statement that "grayscale can get rid of dithering".  Dithering is simply a way to simulate  colors (whatever their hue) that the hardware cannot produce directly by alternating colors that it can.  Grayscale shrinks the 24-bit RGB color space (not counting the alpha channel) to an 8-bit space, which gives 256 grayscale levels.  If you want 10-bit grayscale (1024 levels), for some colors you would need to dither between two grayscale levels, potentially leading to the same "snow" pattern that causes eyestrain, depending on the details of how the dithering is done.  Now, what is possible is that grayscale in conjunction with high contrast might work (again, depending on how high contrast is implemented), but high contrast even without grayscale might work too.

     

    On a completely different note, I purchased the Prevencia coating for my glasses, and I haven't found it to have made any difference at all.  Perhaps it's keeping my eyes safer than they would be without it, but I don't notice less eyestrain.  OTOH I always use f.lux so there probably isn't much extra blue light coming from my monitor anyway.

  • 1,459. Re: Eye strain from LED backlighting in MacBook Pro
    Jessiah1 Level 1 Level 1 (0 points)

    mvanier, Are you sensitive to fluorescent lighting in stores as well or only just LED screens?

  • 1,460. Re: Eye strain from LED backlighting in MacBook Pro
    kvoth Level 1 Level 1 (0 points)

    tfouto wrote:

     

    What is helping you tremendously? the glasses and greyscale? How do you make it greyscale?

     

    The glasses help me in everyday tasks, such as when I go into a store or gym that has bad overhead lighting. They don't "fix" things outright, but they make them easier. But even with the glasses on, troubling LED screens continue to cause issues, though not as bad as without them.

     

    The grayscale on my 2013 macbook pro retina display completely fixes the strain on my eyes. Without grayscale, I get severe symptoms. With it on, I have no issues. When I use my older external monitor, the Dell U2410, I can have color on without severe symptoms.

     

    To turn on grayscale on OSX go to System Preferences -> Accessibility -> Use Grayscale.

     

     

    mvanier wrote:


    do you want to be restricted to grayscale for all of your computing?

     

    I'm just trying to help others out. Grayscale computing > no computing.

     

     

    If that were the case, I would start to look for alternatives to Apple

     

     

    LEDs are not unique to Apple.

     

     

    Also, I disagree with your statement that "grayscale can get rid of dithering".  Dithering is simply a way to simulate  colors (whatever their hue) that the hardware cannot produce directly by alternating colors that it can.  Grayscale shrinks the 24-bit RGB color space (not counting the alpha channel) to an 8-bit space, which gives 256 grayscale levels.  If you want 10-bit grayscale (1024 levels), for some colors you would need to dither between two grayscale levels, potentially leading to the same "snow" pattern that causes eyestrain, depending on the details of how the dithering is done.

     

     

    As you say, if you limit the grayscale to a space that your monitor supports natively in the hardware then you are eliminating dithering.

     

    On a completely different note, I purchased the Prevencia coating for my glasses, and I haven't found it to have made any difference at all.  Perhaps it's keeping my eyes safer than they would be without it, but I don't notice less eyestrain.  OTOH I always use f.lux so there probably isn't much extra blue light coming from my monitor anyway.

     

    f.lux changes the hue of color. It will not eliminiate ultraviolet light nor reduce flicker. I think we should end the conversation on f.lux, it is not a solution.

  • 1,461. Re: Eye strain from LED backlighting in MacBook Pro
    mvanier Level 1 Level 1 (0 points)

    Jessiah, fluorescent lights don't bother me at all.  The very old mechanical-ballast ones that flicker at 60 Hz do bother me but the only place I've seen them in the past few years is our local DMV (dept of motor vehicles), which is just one of many reasons to avoid that place :-)  Even LEDs don't bother me that much; I have an iPhone 4S which initially bothered me but I got used to it.  LED light bulbs do bother me, though some of them are because of flicker (Cree) and others because of color (Philips).

     

    My real problem is flicker, which I am acutely sensitive to.

  • 1,462. Re: Eye strain from LED backlighting in MacBook Pro
    mvanier Level 1 Level 1 (0 points)

    Kvoth, LEDs are not unique to Apple, and I never said they were.  In fact, the whole conversation about LEDs seems to me to be completely misguided, as they are not the primary problem for most of us as far as I can tell (including you), although as you say they may make a bad situation worse.  I'm actively looking into Linux as an alternative because I can control the graphics drivers on Linux in a way that is impossible with Apple or Windows (yay for open source!).  You may not need this or want to go this way.  I'm glad you've found an approach which works for you, and it's fine to let others know in the event that it works for them too, but there are a lot of us here, each with their own particular issues.  BTW I've tried my Macbook with two different CCFL-backlit external monitors, and the flicker and eyestrain was still there, even with grayscale.

  • 1,463. Re: Eye strain from LED backlighting in MacBook Pro
    kvoth Level 1 Level 1 (0 points)

    mvanier --

     

    When did you first start experiencing these issues?

     

    Jessiah has a theory that some people have flicker/spectrum sensitivity, and some have EMF sensitivity. Any chance you're in the EMF camp?

  • 1,464. Re: Eye strain from LED backlighting in MacBook Pro
    mvanier Level 1 Level 1 (0 points)

    Kvoth,

     

    I'm definitely flicker sensitive and somewhat sensitive to blue light, that's all.  I think I've always been this way, but I've only noticed it in the past couple of years with these new monitors/drivers.

  • 1,465. Re: Eye strain from LED backlighting in MacBook Pro
    Jessiah1 Level 1 Level 1 (0 points)

    Mvanier, it is interesting that your sensitive to the lower frequencies, very similar in fact to the range which is known to cause epileptic seizures. Kvoth and myself are sensitive to a wider range of frequencies reaching into the supposed to be invisible to the eye level. Fluorescent lighting is an issue for both of us and that is where the Provencia anti-glare coating is very effective while with LED it may only help by adding just a few minutes of tolerance.

     

    I believe it would be very difficult to say the exact percentage of people here who have the exact same sensitivity to the exact same triggers. Without the anti-glare coating fluorescent lighting makes me just as sick as LED lighting so my level of sensitivity is much greater than yours, LED lighting of any kind triggers migraines almost instantly.Sometimes they go away if I remove myself from exposure quickly but I can feel it starting instantly so I have 0 tolerance to LED. My symptoms are more than eye strain, nausea, fatigue, balance issues, brain dysfunction and many more symptoms.

     

    My symptoms can last for days and I have met several other people who have almost exactly the same level of pain as myself, I would say that your not even close, so why is that? Why do you have some reaction but can tolerate some LED usage and no reaction to fluorescent lighting?

     

    One thing is certain for me (myself being a good measure since I am the extreme), flicker and spectrum are an issue. There are some very blue and bright white fluorescent lamps which are almost as bad as LED lamps for me, but if spectrum were the only issue than why do yellow LED's bother me and fire places? There is plenty of scientific info out there showing increased flicker from blue spectrum lighting, is it that the bight white and blue spectrums flicker more for some reason? I am no scientist but from what I have read this makes sense and Kvoth is getting somewhere with the "Square" light info.

     

    It may be that modern image rendering and dithering are adding to the issue but the LED lighting is the source of the intensity for sure and science will show that, I am sure of it. I have read hundreds of pages about this, I will leave you with this paper link on different lighting tests, check out the results from all the different light sources tested and see the potential for flicker in "Solid state lighting" compared even to fluorescent and also the most pleasant light source, incandescent:

     

    http://www.e3tnw.org/Documents/2011%20IES%20flicker%20paper%20poplawski-miller-F INAL.pdf

     

    I hope this deeper detail about myself and this article help bring some new topics to light:)

  • 1,466. Re: Eye strain from LED backlighting in MacBook Pro
    mvanier Level 1 Level 1 (0 points)

    Jessiah, I'm sorry you have such severe issues.  It certainly puts my more modest issues into perspective.

     

    I have had a severe negative reaction to a yellow LED light bulb (Cree) but that was not because of the color, which was quite pleasant; it was because the light flickered at 120 Hz and the flicker was very deep (all on to all off).   This gave me tremendous eyestrain in a few minutes, presumably because my irises were expanding and contracting very rapidly in response to the flicker.  I gather that most people can't see this and have no issues with this bulb.  I also had a (less severe) issue with a Philips LED bulb which didn't flicker but had a very harsh bluish light, so I'm at least somewhat sensitive to blue light too.

     

    My interest in dithering arose from noticing that connecting a new Macbook to an old CCFL-backlit monitor which did not cause any issues at all when connected to an older Macbook resulted in severe eyestrain.  Given that I'd eliminated the influence of LED backlights (there was none with the CCFL-backlit monitor) and PWM (there was only the softer PWM that CCFL backlights exhibit, which doesn't bother me), something else had to be responsible.  That doesn't rule out the possibility that some people (presumably including you) have severe issues coming from other causes.  We're all trying to understand all causes of eyestrain here, and so in addition to LED blue light sensitivity and PWM, we have to include dithering (or something that seems to be related to dithering) as one of the common causes.

  • 1,467. Re: Eye strain from LED backlighting in MacBook Pro
    mojarvinen Level 1 Level 1 (0 points)

    Yet again I see that people are using the displays that cause problems and try to mitigate it with glasses, grayscaling or something else.

     

    I just still would like to point out - try to eliminate all flickering/dithering displays for a couple of weeks, buy a display that is confirmed not to cause problems to a person sensitive to flicker. Then you might notice that no glasses or grayscaling or similar is needed.

     

     

    When I use a flickering display, my eyes are also so sore that all kinds of lights seem to bother me (like lights in the gym) But that it not actually the gym lights, it's just the fact that I have my eyes open, which causes irritation when my eyes are sore from the flicker.

     

    Just try the displays that I listed, you'll most likely come back reporting that the whole eye issue has resolved.

     

    Yes, it took me too years to realize this and most people cannot just go and purchase $700 display to test. But as I understand, in many countries like US, stuff can be bought and then returned without any specific reason.

     

    I'm now fully on top of what causes irritation and how to resolve it. It has been actually quite amazing last 6 months, as I've had zero irritation and red eyes, until last weekend, when I used the flickering iPad.

     

    I've noticed that nowadays there are a lot of moisturizing eye drop commercials on TV. Also I've noticed that many people seem to have bloodshot eyes, more ofthen than say, 5 years ago.

    My take on this is that people are using flickering LED displays that cause irrititatioin, but blame it on tirednes or the flu, or the wind or what ever, not realizing that it is actually the new LED TV or LED computer display or LED phone that is causing it. (LED is not bad as such, but the on/off cycle that is instant, makes the problem worse than CCFL)

     

    My previous Samsung display was CCFL with PWM of 160 hz. That did cause irritation, but only if I was doing something like gaming 3 hours a night for 5 days in a row - then I just had to stop using a computer for a while.

    It is all along been the flicker.

  • 1,468. Re: Eye strain from LED backlighting in MacBook Pro
    tfouto Level 1 Level 1 (0 points)

    Does anyone understand this issue of 10hz PWM?

     

    I take a shot at 1 second, even if it didn't make any sense, and to my utter suprise i found this:

    low brightness

     

    http://imageshack.us/a/img43/6748/rt7k.jpg

    http://imageshack.us/a/img843/1034/48j8.jpg

     

    this not make any sense... i count 10 lines. This means PWM of 10hz?????

     

    This is really weird... Shouldn't i notice on naked eye?

     

    Then i tried full brightness:

     

    http://imageshack.us/a/img209/5106/5epd.jpg

     

    Am i doing something wrong? I think i must so.

  • 1,469. Re: Eye strain from LED backlighting in MacBook Pro
    StefanD13 Level 1 Level 1 (0 points)

    Hi mvanier,

    I could verify with the frame grabber that when using the proprietary nvidia drivers under Linux, you can control the GPU dithering (nvidia-settings).

    However the eye strain is not gone when disabling it and my best theory now is that the dithering on the monitor side cannot be controlled, and in the end having or not having eye strain is a question of luck and it depends on dithering pattern and colour calibration on both GPU and monitor side.

    By best guess right now is to use a Linux notebook with an nvidia GPU and disable the GPU dithering, although is also probably not ensured that the notebook panel is not doing some dithering on its own which cannot be controlled...

    I'm also not aware of any stand-alone monitor which is not using dithering. Even if the panel is 8bit capable it is still using dithering to increase to 10bit (for precise color calibration).

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