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Discussion Starter · #1 ·
Many people claim that they like LCDs better than CRTs because they're easier on eyes. I don't get it. With me, they both strain the eyes but in different ways. CRTs flicker and LCDs are very bright in contrast, so they both hurt my eyes after staring at them for too long. So, I have a hunch that this "easier on the eyes" thing is just a myth.


So, do LCDs really put less strain on your eyes? If it does, then why doesn't the bright contrast kill your eyes like it does to me?
 

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Any display will hurt your eyes if you have it lit up like a nuclear reaction. Lower the brightness to a level suitable for your viewing environment and sit far enough back that it fills up a confortable amount of your viewing cone, and you've made a bigger difference than you'd get from changing technology.
 

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Quote:
Originally Posted by xraffle /forum/post/15580285


Many people claim that they like LCDs better than CRTs because they're easier on eyes. I don't get it. With me, they both strain the eyes but in different ways. CRTs flicker and LCDs are very bright in contrast, so they both hurt my eyes after staring at them for too long. So, I have a hunch that this "easier on the eyes" thing is just a myth.


So, do LCDs really put less strain on your eyes? If it does, then why doesn't the bright contrast kill your eyes like it does to me?

Everybody is different. If it's night time and I have my 52A750 on with backlight of 10, then my brain is slowly melting away within me, however I NEVER go past a backlight of 2 in night time viewing. Personally, I would think if anything, LCDs would cause more strain simply due to the bright whites LCD's give. I have my 52A750 in a 12x12 room, and the only time my eyes wear out is when I play Dynasty Warriors 6 and have to look clear across the screen to kill some guy, then look all the way back across the screen..........but that's more of a size issue.
As long as my settings are correct, my eyes do fine, however my friend has his eyes go to the crapper fairly quicker, although that's how his eyes have always been, even with CRT TVs.
 

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Quote:
Originally Posted by xraffle /forum/post/15580285


Many people claim that they like LCDs better than CRTs because they're easier on eyes. I don't get it. With me, they both strain the eyes but in different ways. CRTs flicker and LCDs are very bright in contrast, so they both hurt my eyes after staring at them for too long. So, I have a hunch that this "easier on the eyes" thing is just a myth.


So, do LCDs really put less strain on your eyes? If it does, then why doesn't the bright contrast kill your eyes like it does to me?

LCD display average brightness is not controlled like it is in a CRT or Plasma. This makes it very difficult to watch in medium to low ambient light because your pupil cannot adjust to the huge shifts in average brightness. To compensate you then turn the backlight down but it does not get rid of the problem and actually hurts low APL peak brightness. On the other hand, in high ambient light your pupil is already adjusted and small and the display shifting average brightness should not induce eye strain.


Plasma and CRT are the opposite in that they control average brightness while maintaining high peak brightness at low APL. This is ideal for medium to low ambient light viewing. However, in high ambient light, with your pupil small, Plasma and CRT will look much dimmer than LCD due to this brightness control. Also, as you say, both CRT and Plasma flicker which also causes eye strain for some.


Ideally, LD-LCD, or high lumen Plasma, should incorporate an "optional" average brightness control (ABL - automatic brightness limiter) as to be suited for viewing in all environments


See the following chart that describes display brightness control. Pay attention to the average brightness plots as that is what is determining eye strain.

 

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Quote:
Originally Posted by Carled /forum/post/15580589


That graph doesn't compensate for gamma.



Edit: Or did I just mis-read it? Is that just showing the effect of the ABL?

Yes, data is taken at a static IRE (100IRE) and only APL is changed (size of window, % of screen). Data is also normalized at % of zero (all displays are normalized to the same peak brightness at 0%)
 

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Discussion Starter · #7 ·
LCD TVs aren't that bad as I don't sit that close to them, but LCD monitors are another story. They kill my eyes because I sit up close and white levels are really bright.
 

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In simple terms, eye strain is produced by two things;


1. Brightness level

2. Duty Cycle


Duty cycle in effect is a brightness issue, as a display with a nominal light output of, say 100cdm2 and a 10% duty cycle needs to output 1000cdm2 during the time it is actually outputting light. Likewise a 1% duty cycle would need 10000cdm2.


Quote:
Originally Posted by xrox /forum/post/15580677


Yes, data is taken at a static IRE (100IRE) and only APL is changed (size of window, % of screen). Data is also normalized at % of zero (all displays are normalized to the same peak brightness at 0%)

Yeah, I was rushing off to work and mistook %Stimulus for White Window size.
 

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Quote:
Originally Posted by xrox /forum/post/15580564


LCD display average brightness is not controlled like it is in a CRT or Plasma. This makes it very difficult to watch in medium to low ambient light because your pupil cannot adjust to the huge shifts in average brightness. To compensate you then turn the backlight down but it does not get rid of the problem and actually hurts low APL peak brightness. On the other hand, in high ambient light your pupil is already adjusted and small and the display shifting average brightness should not induce eye strain.


Plasma and CRT are the opposite in that they control average brightness while maintaining high peak brightness at low APL. This is ideal for medium to low ambient light viewing. However, in high ambient light, with your pupil small, Plasma and CRT will look much dimmer than LCD due to this brightness control. Also, as you say, both CRT and Plasma flicker which also causes eye strain for some.


Ideally, LD-LCD, or high lumen Plasma, should incorporate an "optional" average brightness control (ABL - automatic brightness limiter) as to be suited for viewing in all environments


See the following chart that describes display brightness control. Pay attention to the average brightness plots as that is what is determining eye strain.


Could LCD's incorporate ABL circuits to make their graph line more like crt/plasma concerning "peak brightness characteristics?" Is this what LED local dimming LCD's are trying to accomplish?


I went from a 40" to 46" LCD at 10 feet, and am having eye strain issues. One thing that has helped (along with turning down brightness/backlight) has been the use of a bias light behind the TV.


I am considering trying (do I dare say it in the LCD forum) a plasma to see how I do with the eye strain. The PDP peak brightness and average brightness charts look more like what one would expect and want (increase brightness when picture is dark, decrease brightness when picture is bright). The LCD chart seems backwards from what is needed.
 

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Quote:
Originally Posted by montanaman /forum/post/15583941


Could LCD's incorporate ABL circuits to make their graph line more like crt/plasma concerning "peak brightness characteristics?" Is this what LED local dimming LCD's are trying to accomplish?


I went from a 40" to 46" LCD at 10 feet, and am having eye strain issues. One thing that has helped (along with turning down brightness/backlight) has been the use of a bias light behind the TV.


I am considering trying (do I dare say it in the LCD forum) a plasma to see how I do with the eye strain. The PDP peak brightness and average brightness charts look more like what one would expect and want (increase brightness when picture is dark, decrease brightness when picture is bright). The LCD chart seems backwards from what is needed.

Incorporation of an ABL has advantages and disadvantages like I pointed out in my original post. Ideally, an optional ABL would be best. Pioneer plasma displays have power save modes to adjust the ABL but no way to turn it off.


Local dimming LEDs have the capability to incorporate dynamic brightness control (ABL) but that is not what local dimming is. Local dimming is purely to enhance contrast.


A bias light reduses eye strain by raising the average brightness reaching your pupil. In other words your pupil gets smaller thanks to the constant bias light and therefore is less impacted when the display switches from a dark scene to a bright scene. There is some dark adaptation issues that are happening as well.
 

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The auto energy saving feature in my Samsung 750 does a good job of controlling the backlight output and helps produce consistent brightness and black levels, and I don't notice the shifts in the backlight.
 

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One possible reason why LCDs would reduce eye strain is if they have an anti-glare surface. I purchased my Sharp Aquos 32D64U for exactly that reason... it's facing directly towards a window and I like to watch during the day with the blinds open. I find the reflections from a glossy screen to be impossible.


It's very unusual to see a CRT with AG.
 
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