Author Topic: what are monochrome 4K-LCDs used for?  (Read 1105 times)

0 Members and 1 Guest are viewing this topic.

Offline 0db

  • Regular Contributor
  • *
  • Posts: 246
  • Country: zm
what are monochrome 4K-LCDs used for?
« on: March 20, 2020, 09:37:52 am »
I can understand color and retina 4K LCDs, but what about monochrome 4K-LCDs?
I see a lot of these LCDs for sale, but I fail to understand the purpose ...
 

Offline AndyC_772

  • Super Contributor
  • ***
  • Posts: 3630
  • Country: gb
  • Professional design engineer
    • Cawte Engineering | Reliable Electronics
« Last Edit: March 20, 2020, 09:52:54 am by AndyC_772 »
 

Offline Deni

  • Regular Contributor
  • *
  • Posts: 59
  • Country: hr
Re: what are monochrome 4K-LCDs used for?
« Reply #2 on: March 20, 2020, 09:51:16 am »
I can understand color and retina 4K LCDs, but what about monochrome 4K-LCDs?

Perhaps in medical imaging (X-rays). Subtle shades in this kind of imaging are hard to reproduce with RGB-types.
 

Offline 0db

  • Regular Contributor
  • *
  • Posts: 246
  • Country: zm
Re: what are monochrome 4K-LCDs used for?
« Reply #3 on: March 20, 2020, 09:54:57 am »
MSLA printers?

Perhaps in medical imaging (X-rays). Subtle shades in this kind of imaging are hard to reproduce with RGB-types.


Very interesting! Never heard before, thank you guys!
 

Offline mikeselectricstuff

  • Super Contributor
  • ***
  • Posts: 12136
  • Country: gb
    • Mike's Electric Stuff
Re: what are monochrome 4K-LCDs used for?
« Reply #4 on: March 20, 2020, 10:01:08 am »
Also any application where high contrast and/or good power efficiency is more important than colour -  colour LCDs lose about 2/3rds of the backlight power in the RGB filters.
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
Day Job: Mostly LEDs
 

Online NiHaoMike

  • Super Contributor
  • ***
  • Posts: 6352
  • Country: us
  • "Don't turn it on - Take it apart!"
    • Facebook Page
Re: what are monochrome 4K-LCDs used for?
« Reply #5 on: March 20, 2020, 12:53:26 pm »
If the response time is fast enough, they can display colors with a RGB backlight pulsing individual colors just like a DLP projector. In practice, it's difficult to make LCDs fast enough for that to work well, but 8 years or so ago, there was a tablet that used that technology to make a dual mode display capable of operating as a color display with about half the power usage of conventional LCD (since the fast refreshing uses a little more power) or as a monochrome eink like display with the backlight turned off.
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline tooki

  • Super Contributor
  • ***
  • Posts: 5251
  • Country: ch
Re: what are monochrome 4K-LCDs used for?
« Reply #6 on: March 20, 2020, 01:26:41 pm »
If the response time is fast enough, they can display colors with a RGB backlight pulsing individual colors just like a DLP projector. In practice, it's difficult to make LCDs fast enough for that to work well, but 8 years or so ago, there was a tablet that used that technology to make a dual mode display capable of operating as a color display with about half the power usage of conventional LCD (since the fast refreshing uses a little more power) or as a monochrome eink like display with the backlight turned off.
Ugh, I hope this doesn’t become popular until the technology allows for extremely fast rates like 1000Hz. I am sensitive to flicker, and I can spot a DLP projector from a mile away when it’s a mostly dark background with a few bright objects, as the famous rainbow effect.

I know this technique is already used in small LED-lit LCD projectors.
 

Offline SiliconWizard

  • Super Contributor
  • ***
  • Posts: 5447
  • Country: fr
Re: what are monochrome 4K-LCDs used for?
« Reply #7 on: March 20, 2020, 04:04:04 pm »
By monochrome, do you mean grayscale (and if so, how many bits per pixel?) or just 1 bit per pixel?
 

Offline mzzj

  • Frequent Contributor
  • **
  • Posts: 959
  • Country: fi
Re: what are monochrome 4K-LCDs used for?
« Reply #8 on: March 20, 2020, 06:45:30 pm »
If the response time is fast enough, they can display colors with a RGB backlight pulsing individual colors just like a DLP projector. In practice, it's difficult to make LCDs fast enough for that to work well, but 8 years or so ago, there was a tablet that used that technology to make a dual mode display capable of operating as a color display with about half the power usage of conventional LCD (since the fast refreshing uses a little more power) or as a monochrome eink like display with the backlight turned off.
3LCD is common way to do projectors
https://electronics.howstuffworks.com/lcd-projectors1.htm
 

Offline tooki

  • Super Contributor
  • ***
  • Posts: 5251
  • Country: ch
Re: what are monochrome 4K-LCDs used for?
« Reply #9 on: March 20, 2020, 11:42:12 pm »
If the response time is fast enough, they can display colors with a RGB backlight pulsing individual colors just like a DLP projector. In practice, it's difficult to make LCDs fast enough for that to work well, but 8 years or so ago, there was a tablet that used that technology to make a dual mode display capable of operating as a color display with about half the power usage of conventional LCD (since the fast refreshing uses a little more power) or as a monochrome eink like display with the backlight turned off.
3LCD is common way to do projectors
https://electronics.howstuffworks.com/lcd-projectors1.htm
Well yeah, we all knew that. But the discussion is about using one LCD with an alternating-color light source.
 

Online NiHaoMike

  • Super Contributor
  • ***
  • Posts: 6352
  • Country: us
  • "Don't turn it on - Take it apart!"
    • Facebook Page
Re: what are monochrome 4K-LCDs used for?
« Reply #10 on: March 21, 2020, 12:31:55 am »
Ugh, I hope this doesn’t become popular until the technology allows for extremely fast rates like 1000Hz. I am sensitive to flicker, and I can spot a DLP projector from a mile away when it’s a mostly dark background with a few bright objects, as the famous rainbow effect.
That's exactly why it has not caught on. I'm not sure why so far, nobody has tried that in a device that's primarily monochrome with colors mostly just for minor things like accents, for example, an ebook reader. (The tablet tried to be a normal tablet with "eink mode".)
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline james_s

  • Super Contributor
  • ***
  • Posts: 12245
  • Country: us
Re: what are monochrome 4K-LCDs used for?
« Reply #11 on: March 21, 2020, 12:42:13 am »
I haven't looked at the state of the art, but B&W CRTs were very common for medical imaging like ultrasound, they provide a sharper more detailed display than color CRTs and the same is likely true for LCDs. Back in the day at least TV studios also used B&W monitors alongside color because they tend to show more detail and make some types of flaws in the image more visible.
 
The following users thanked this post: tooki

Offline amyk

  • Super Contributor
  • ***
  • Posts: 6848
Re: what are monochrome 4K-LCDs used for?
« Reply #12 on: March 21, 2020, 01:39:28 am »
Eizo makes a bunch of them for medical applications. Prices are in the 4-5 figure range.
 

Offline Circlotron

  • Super Contributor
  • ***
  • Posts: 1914
  • Country: au
Re: what are monochrome 4K-LCDs used for?
« Reply #13 on: March 21, 2020, 02:17:53 am »
You could say a 4K lcd actually has 12K horizontal pixels whereas a monochrome one would only have 4K. Wouldn’t the colour one give better resolution if it used sub pixel rendering?
 

Offline james_s

  • Super Contributor
  • ***
  • Posts: 12245
  • Country: us
Re: what are monochrome 4K-LCDs used for?
« Reply #14 on: March 21, 2020, 04:57:47 am »
Perhaps? But maybe the color filters would result in a less clear image? There must be a reason these things exist.
 

Offline helius

  • Super Contributor
  • ***
  • Posts: 3015
  • Country: us
Re: what are monochrome 4K-LCDs used for?
« Reply #15 on: March 21, 2020, 05:35:56 am »
Subpixel rendering is only useful for bitonal objects like fonts (and most implementations only support fonts).
 

Offline tooki

  • Super Contributor
  • ***
  • Posts: 5251
  • Country: ch
Re: what are monochrome 4K-LCDs used for?
« Reply #16 on: March 21, 2020, 01:21:06 pm »
Ugh, I hope this doesn’t become popular until the technology allows for extremely fast rates like 1000Hz. I am sensitive to flicker, and I can spot a DLP projector from a mile away when it’s a mostly dark background with a few bright objects, as the famous rainbow effect.
That's exactly why it has not caught on. I'm not sure why so far, nobody has tried that in a device that's primarily monochrome with colors mostly just for minor things like accents, for example, an ebook reader. (The tablet tried to be a normal tablet with "eink mode".)
How would that make any difference? It's not motion in the image that causes the rainbow effect, it's eye movements of the viewer.

I mean, you could use very fast backlight pulsing to change the backlight color of an e-reader, but what use is that, or rather, what about that wouldn't be achievable with regular LED backlighting, just with RGB LEDs or various shades of white, if it's just adjusting the color temperature.


You could say a 4K lcd actually has 12K horizontal pixels whereas a monochrome one would only have 4K. Wouldn’t the colour one give better resolution if it used sub pixel rendering?
In theory, yes. But it comes with its own tradeoffs, like the fact that white areas have three times as many gaps in them as a monochrome LCD would.

Subpixel rendering is only useful for bitonal objects like fonts (and most implementations only support fonts).
There's no reason for it to apply only to bitonal things — if anything, it only really works well for things that have variations in brightness, which is why we invariably apply subpixel rendering to antialiased font rendering, not bitonal rendering. Without the antialiasing, the color fringing is too distracting.

Most implementations of subpixel rendering are very limited in where they can apply, insofar as I don't know of any that are applied to anything but text, and many of those only apply it to text on white or black backgrounds. But it works beautifully on color backgrounds, too, and there's no reason it couldn't be applied to complex backgrounds*. I suspect that if high-resolution (as in, pixel density) displays hadn't become available, we might have invested the effort to make our graphics drawing engines perform subpixel rendering on everything. But with the high-res displays with pixels so small as to be invisible becoming commonplace (and many of them using complex nonuniform subpixel arrangements), it became easier to simply brute force it in hardware.

*and this can be tested by taking subpixel-rendered text on a white background, and then photoshopping that onto an arbitrary background image. The result is actually flawless. (At least, in my experiments of essentially using it as subpixel "ink" onto a light background. I haven't tried anything where the text is lighter than the background.)
 

Offline jogri

  • Frequent Contributor
  • **
  • Posts: 257
  • Country: de
Re: what are monochrome 4K-LCDs used for?
« Reply #17 on: March 21, 2020, 01:42:39 pm »
Eizo makes a bunch of them for medical applications. Prices are in the 4-5 figure range.

Those are used for viewing X-ray images, they even need to be calibrated every so often to make sure the colour tones are exactly right as the difference between healthy tissue and a tumor can be hard to see (remember, we are talking about differences in density), especially with small tumors.

If you see them on sale on ebay etc they probably failed the test/calibration.
 

Offline SiliconWizard

  • Super Contributor
  • ***
  • Posts: 5447
  • Country: fr
Re: what are monochrome 4K-LCDs used for?
« Reply #18 on: March 21, 2020, 03:11:03 pm »
You could say a 4K lcd actually has 12K horizontal pixels whereas a monochrome one would only have 4K. Wouldn’t the colour one give better resolution if it used sub pixel rendering?

Nah. The spatially distributed RGB dots will always make the image look a little fuzzier. If you want to look at grayscale images only, you can't beat a purely grayscale panel IMO.
Besides, given they are simpler to design, they may also have better luminance resolution (that's why I was asking for bit depth). A typical RGB panel has 6 to 8 bits per individual dot, the grayscale panels may have more (although I'd like to see specs!)
 

Offline Miyuki

  • Frequent Contributor
  • **
  • Posts: 384
  • Country: cz
    • Me on youtube
Re: what are monochrome 4K-LCDs used for?
« Reply #19 on: March 21, 2020, 04:12:18 pm »
EIZO medical monochrome panels have up to 14-bit tones it is way more than conventional ones
 
The following users thanked this post: tooki, SiliconWizard


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf