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How many of you hate blue led displays? — Parallax Forums

How many of you hate blue led displays?

frank freedmanfrank freedman Posts: 1,983
edited 2020-10-29 00:46 in General Discussion
Finishing work in a normally lit room Nearly impossible to read blue numeric display from reasonable distance. Dim white somewhat better. Please give me red, green (sorta), maybe yellow, or white. Anyone else have thoughts / opinions on this?

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    I definitely prefer amber.

    -Phil
  • DigitalBobDigitalBob Posts: 1,513
    Red is pretty much the standard. What's with the post above looks like a spammer from India.
  • Clock LoopClock Loop Posts: 2,069
    DigitalBob wrote: »
    What's with the post above looks like a spammer from India.

    The forum software that parallax uses has been victim to AD bots for a long time now.
    Just flag it and report spam.
  • Buck RogersBuck Rogers Posts: 2,185
    Clock Loop wrote: »
    DigitalBob wrote: »
    What's with the post above looks like a spammer from India.

    The forum software that parallax uses has been victim to AD bots for a long time now.
    Just flag it and report spam.

    Way ahead of you both. I did that already.
    ----

    Mascot is on a sabbatical.
  • Wuerfel_21Wuerfel_21 Posts: 5,052
    Yeah, blue and blue-derived (pink, some kinds of white, some kinds UV?) LEDs kinda blur out at a distance. Not sure if that's the LEDs fault or just the physical properties of air (blue is diffused heavily, which is why the sky is blue during the day)
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2020-10-29 19:22
    Wuerfel_21 wrote:
    Yeah, blue and blue-derived (pink, some kinds of white, some kinds UV?) LEDs kinda blur out at a distance. Not sure if that's the LEDs fault or just the physical properties of air (blue is diffused heavily, which is why the sky is blue during the day)
    It's a property of the human eye. The lens has chromatic aberration, which means that different colors focus at different distances. Distant blue subjects tend to focus in front of the retina, rather than on it, causing a blurry sensation.

    -Phil
  • banjobanjo Posts: 447
    Phil Pilgrim (PhiPi) wrote: »
    Wuerfel_21 wrote:
    Yeah, blue and blue-derived (pink, some kinds of white, some kinds UV?) LEDs kinda blur out at a distance. Not sure if that's the LEDs fault or just the physical properties of air (blue is diffused heavily, which is why the sky is blue during the day)
    It's a property of the human eye. The lens has chromatic aberration, which means that different colors focus at different distances. Distant blue subjects tend to focus in front of the retina, rather than on it, causing a blurry sensation.

    -Phil

    Thx Phil for the scientific explanation why I too dislike blue LEDs and barely tolerate other colours!
    Paraphrasing Henry Ford, "A LED can be of any colour as long as it's black." = turned off
  • Dave HeinDave Hein Posts: 6,347
    As a person ages there is a reduction in visual acuity for colors. It starts at the higher frequencies, such a blue. I've noticed that my right eye does not see blue as sharply as my left eye does. There may be a chromatic aberration aspect to it, but it also has something to do with the optical receptors in the retina.
  • Wuerfel_21Wuerfel_21 Posts: 5,052
    edited 2020-10-29 21:18
    Phil Pilgrim (PhiPi) wrote: »
    Wuerfel_21 wrote:
    Yeah, blue and blue-derived (pink, some kinds of white, some kinds UV?) LEDs kinda blur out at a distance. Not sure if that's the LEDs fault or just the physical properties of air (blue is diffused heavily, which is why the sky is blue during the day)
    It's a property of the human eye. The lens has chromatic aberration, which means that different colors focus at different distances. Distant blue subjects tend to focus in front of the retina, rather than on it, causing a blurry sensation.

    -Phil

    Indeed, it does not show up on a camera. In reality, this pink LED has a strong blue halo.


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  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    Wuerfel_21 wrote:
    Indeed, it does not show up on a camera.
    Yup, all but the very cheapest cameras have color-corrected lenses that exhibit little or no chromatic aberration. This is often accomplished by using compound lenses made of two different kinds of glass (e.g. crown and flint) that have different indices of refraction. They are combined in such a way as to cancel out the aberration.

    -Phil
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2020-10-30 00:18
    Rod cells in the retina are more sensitive to blue than are cone cells. That gives a night vision peak at 507nm and a day vision peak at 555nm. Rod cells don't see detail, and they don't see into the red at all. Similarly cone cells don't see deep into the blue. What use would that be for a display? I don't know. How about a scotopic flashlight/display for a halloween snipe hunt, ghostly images through the trees?

    http://hyperphysics.phy-astr.gsu.edu/hbase/vision/bright.html

  • potatoheadpotatohead Posts: 10,261
    Not only is there aberration like Phil talked about, but we have very few Blue receptors. Much of our blue perception is interpolated. Blue cones are about 2 to 3 percent of our total number of color receptors.
  • DigitalBobDigitalBob Posts: 1,513
    Red is the easiest on the eyes, this is why it's used in aircraft cockpits.
  • rbehmrbehm Posts: 102
    DigitalBob wrote: »
    Red is the easiest on the eyes, this is why it's used in aircraft cockpits.

    But only in non NVIS cockpits. My customers (military, police, med rescue) use night vision goggles in their helicopters. These are sensitive in near infrared and red.
    An NVIS compatible cockpit may not have anything emitting red color (anything with lambda >= 600nm).

    Eeven normal cockpit usually have no red displays, anything red means ALARM.
  • Cluso99Cluso99 Posts: 18,069
    edited 2020-10-30 06:59
    DigitalBob wrote: »
    Red is the easiest on the eyes, this is why it's used in aircraft cockpits.
    I think red is used to preserve nightvision.

    I like blue, and the other colors too. Just don't like the blinding bright LEDs that seem to be on boards and equipment these days. Think designers have forgotten that LEDs have become brighter and they don't increase the series resistor values accordingly!
  • kwinnkwinn Posts: 8,697
    Cluso99 wrote: »
    DigitalBob wrote: »
    Red is the easiest on the eyes, this is why it's used in aircraft cockpits.
    I think red is used to preserve nightvision.


    I like blue, and the other colors too. Just don't like the blinding bright LEDs that seem to be on boards and equipment these days. Think designers have forgotten that LEDs have become brighter and they don't increase the series resistor values accordingly!

    Red is definitely the best choice when night vision needs to be preserved, and I find the newer red leds are just as bright at 2 to 3 mA as some of the oldest ones I have at 10 to 15 mA. I now use a 1.2K resistor for most applications.
  • Cluso99Cluso99 Posts: 18,069
    edited 2020-10-30 19:59
    I use 3K3 or 5K (4K99) mostly but 10K sometimes. Never a problem.
    BTW I used 3K3 on my SimpleModem designs way back in 1992.
  • pmrobertpmrobert Posts: 673
    Dave Hein wrote: »
    As a person ages there is a reduction in visual acuity for colors. It starts at the higher frequencies, such a blue. I've noticed that my right eye does not see blue as sharply as my left eye does. There may be a chromatic aberration aspect to it, but it also has something to do with the optical receptors in the retina.
    Dave, I took a racquetball to the eye few years ago ( I was 50ish) and as a result developed a traumatic cataract in the lens which which was subsequently replaced with an artificial lens. All colors were so much more vibrant, especially the blues. The eye surgeon stated that as we age the lens becomes somewhat of a yellowish tinge accounting for my experience. If I view things one eye at a time the effect is very marked. Fun fact: the natural lens has a fair amount of UV filtering built in. The plastic one does not. I can see way into the UV spectrum now with the one eye. Also - do not play racquetball at all if you forget the goggles! One time is all it takes. I got lucky and have phenomenal vision in the affected eye without any sort of corrective lenses.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2020-10-30 22:44
    pmrobert wrote:
    One time is all it takes. I got lucky and have phenomenal vision in the affected eye without any sort of corrective lenses.
    Is the replacement lens able to focus on near and distant subjects using the eye muscles to compress and expand it like they do with a natural lens?

    -Phil
  • John AbshierJohn Abshier Posts: 1,116
    My replacement lens is not able to focus.

    John Abshier
  • pmrobertpmrobert Posts: 673
    edited 2020-10-31 00:46
    I had to cough up additional funds for the upgrade to a multifocal artificial lens. It was a little strange for the first week post op but works very, very well for me afterwards. The brain is able to sort through the multiple images that are projected onto the retina after a short while. If you search on "multifocal artificial lens definition" you'll find a bit of information.
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  • pmrobertpmrobert Posts: 673
    edited 2020-10-31 01:10
    Phil Pilgrim (PhiPi) wrote: »
    pmrobert wrote:
    One time is all it takes. I got lucky and have phenomenal vision in the affected eye without any sort of corrective lenses.
    Is the replacement lens able to focus on near and distant subjects using the eye muscles to compress and expand it like they do with a natural lens?

    -Phil

    No, a multifocal artificial lens does not utilize the ciliary muscles in any way. It projects multiple images from varying distances onto the retina and neural processing melds them together (after a short accommodation period, for me a week) into a perceived sharp image. It was a leap of faith for me to spend the extra $2500 for the upgrade. The ophthalmologic surgeon was correct.
  • pmrobertpmrobert Posts: 673
    edited 2020-10-31 01:09
    Also - yes. I find blue LED displays to be much less useful than other colors. 100% agree with the excessive brightness issue as well. Amber text is nice unless it's being used as a warning indicator. White is very nice as a baseline, color change to indicate parameters needing attention or notice. Flashing for a short period isn't terrible for quick changes past a certain threshold. Log files are essential.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    pmrobert wrote:
    No, a multifocal artificial lens does not utilize the ciliary muscles in any way. It projects multiple images from varying distances onto the retina and neural processing melds them together (after a short accommodation period, for me a week) into a perceived sharp image. It was a leap of faith for me to spend the extra $2500 for the upgrade. The ophthalmologic surgeon was correct.
    Wow! I'm amazed that the superimposed images don't just drive you crazy. Do you ever revert to your first week's experience, say, right after getting up in the morning?

    -Phil
  • pmrobertpmrobert Posts: 673
    edited 2020-10-31 11:08
    The first week I experienced vision similar to a camera autofocusing. If I switched my attention from a close object to a distant object there would be a brief yet perceptible period where the image was not as sharp as it could be then "popped" into sharp focus. That and at night I was aware of the concentric rings physically present in the lens. After that "training" period the lens is completely imperceptible at all times. The surgeon said that there are some patients who fail and the lens must be replaced with a standard monofocal. I've used monocular correction (contact in dominant eye) for myopia for decades so was a good candidate for the multifocal according to the doc. He was right. I can't even start to imagine the neural processing that occurs to synthesize the good image I perceive given the multiple images present on the retina.
  • whickerwhicker Posts: 749
    I've noticed for whatever reason, that practically all LCD backlit monitors and HD TVs default to a very blue (cold) color temperature.

    As well as just from experience of purchasing many LCDs over the years, one can see this when driving around the city near or after sunset and seeing the blue glow emitting from people's living rooms.

    One of the very first things I do after powering on a new panel is configure the color temperature towards or well into "warm". White should be casting a generally neutral daylight white at least.

    Us younger generation have a hard time shutting down mentally at night, and part of it is all this blue light being cast from power LEDs, clocks, indicators, room lamps, display monitors, and cellphone screens haven't been helping.

    It's a case of biology using blue light to heighten alertness and block melatonin release.

    So always-on blue LEDs on hobby projects either get replaced, get covered up, or are given the "sharpie" treatment.
  • AwesomeCronkAwesomeCronk Posts: 1,055
    I find this odd because many sleep studies have found blue to be the best color to fall asleep to.
  • Dave HeinDave Hein Posts: 6,347
    edited 2020-11-02 21:18
    That's probably because the eyes can't focus on anything, and the person ends up squinting, and then the eyelids transition to being fully shut, and then the brain just gives up and falls asleep. :)
  • whickerwhicker Posts: 749
    AwesomeCronk wrote: »
    I find this odd because many sleep studies have found blue to be the best color to fall asleep to.
    If you're a mouse!
    Gotta watch those studies for their methodology.
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