Display screens & black colors

[SH64]

First sorry if i'm posting in the wrong forum. mods feel free to move the thread to the correct forum if needed so i get more responses for this question.

so we're having a debate about the fact of how the true black color is produced into screens : one is insisting that the screen just "turns off" itself or the needed pixels in order to show the darkest black color , in other words the screen cannot show a black pixel that is darker than the screen itself when its switched off.

other though say its produced just like other colors meaning that you will still be able to see black darker than the screen pixels when its switched off.

whats is the technical answer for that ?

& you may add how HDR or LDR will come into this or if it has any relation to the subject because AFAIK HDR's perpose is to show colors (black or white) that are either brighter or darker than what the screen can produce.

the debate was a part of a larger debate we're having which is : LCD screens can't produce true dark/bright or black/white colors as CRT's or Plasma's do.
if you can add your views of this aswell that will be great , but for now you can just focus on the main question.

thanks in advance!

 

[bystander]

so we're having a debate about the fact of how the true black color is produced into screens : one is insisting that the screen just "turns off" itself or the needed pixels in order to show the darkest black color , in other words the screen cannot show a black pixel that is darker than the screen itself when its switched off.

other though say its produced just like other colors meaning that you will still be able to see black darker than the screen pixels when its switched off.

whats is the technical answer for that ?

& you may add how HDR or LDR will come into this or if it has any relation to the subject because AFAIK HDR's perpose is to show colors (black or white) that are either brighter or darker than what the screen can produce.

the debate was a part of a larger debate we're having which is : LCD screens can't produce true dark/bright or black/white colors as CRT's or Plasma's do.
if you can add your views of this aswell that will be great , but for now you can just focus on the main question.

thanks in advance!

From my understanding LCD produce colours by "filtering" out the colours you don't want/need to see. So for black, it prevents any light coming through at all.

Plasmas and CRT will for blacks "turn off" the pixels which are black so they aren't displaying any colour there.

As far as I understand things, the colour black cannot be produced as it occurs when an object absorbs all the colours you can see.

 

[Blazkowicz]

I remember hearing that on CRT it's a matter of the brain/eyes being fooled into seeing black as a result of the contrast, well that's an explanation especially needed for older CRT sets, as they look grey when switched off.

 

[London Geezer]

I remember hearing that on CRT it's a matter of the brain/eyes being fooled into seeing black as a result of the contrast, well that's an explanation especially needed for older CRT sets, as they look grey when switched off.

That's still true, especially for LCD screens.

 

[Xmas]

First sorry if i'm posting in the wrong forum. mods feel free to move the thread to the correct forum if needed so i get more responses for this question.

so we're having a debate about the fact of how the true black color is produced into screens : one is insisting that the screen just "turns off" itself or the needed pixels in order to show the darkest black color , in other words the screen cannot show a black pixel that is darker than the screen itself when its switched off.

This is correct for most display types and pretty much all color displays. Exceptions are non-emitting displays like e-paper, which can remain white in their off state, and the standard black-on-background monochrome LCD where you only see the background color in the off state.

In any case, every display reflects some of the ambient light, so you can only get "true black" if you're in a darkened room. For our eyes however, only "relative black" is relevant.

& you may add how HDR or LDR will come into this or if it has any relation to the subject because AFAIK HDR's perpose is to show colors (black or white) that are either brighter or darker than what the screen can produce.

HDR has no relation to how well a screen can display black.

the debate was a part of a larger debate we're having which is : LCD screens can't produce true dark/bright or black/white colors as CRT's or Plasma's do.
if you can add your views of this aswell that will be great , but for now you can just focus on the main question.

LCDs produce colors by "taking away" from a white backlight. First there is a color filter mask that creates red, green and blue subpixels. Then there is a layer that can be made more or less translucent by applying a voltage to each subpixel. However, some of the backlight is always leaking through, thus black levels of ordinary LCDs are relatively poor. LCDs have no problem at all producing bright colors, all you need is a bright backlight.

By using a matrix of LEDs as backlight, LCDs can indeed produce "true black" as in "not emitting any light" because the backlight can be turned off locally. This is expensive and rare, unfortunately.

 

[SH64]

Thanks everyone!

In any case, every display reflects some of the ambient light, so you can only get "true black" if you're in a darkened room.

Thats what i was thinking too ...

so i take it that most of you guys agree that LCD's dont produce black/white colors as good as plasma's or CRT's due to the filtering process (& that backlight?).

 

[Xmas]

so i take it that most of you guys agree that LCD's dont produce black/white colors as good as plasma's or CRT's due to the filtering process (& that backlight?).

Most LCDs don't display black and dark colors very well. I'm not sure what you mean with "black/white colors". There is no problem with white or bright colors, it really only affects the dark end.

 

[London Geezer]

Most LCDs don't display black and dark colors very well. I'm not sure what you mean with "black/white colors". There is no problem with white or bright colors, it really only affects the dark end.

There definitely isn't a problem with bright colours and white on LCD. In fact, on some sets, it is recommended to turn the backlight down a bit cause it can get TOO bright, not literally blinding, but VERY bright. I found myself squinting a few times, on some sets with backlight turned to maximum, when the screen would just explode in a bright-as-the-sun scene or such.

 

[Blazkowicz]

another problem with LCD black, even if it's half decent black level there's terrible banding in dark areas coming from the (usual) 6-bitness of the panel.

 

[PeterAce]

After only 2 years my 19" Iiyama VisionMaster Pro 454 (Dimondtron U2-CRT) had to be replaced (it's OSD stopped working correctly, a strange banding problem just appered and the screen at 100% brightness was still quite dark!).

So I just replaced it with the LG 19" L1960TQ-BF LCD. It's a good panel as it's spec'ed at 4ms mesured at 2ms and it has a very high contrast ratio (2000:1). It has some back-light blead from the sides (but this is very small). I was quite shocked that blacks/dark greys are so very poor.

http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=492005

It has one dead pixel (technically a hot pixel stuck at light blue).

Very happy with it so far, infact my bro liked it so much he ordered one as well (received his yesterday, lucky git has no dead pixels on his!). ClearType font smoothing/AA is great for the eyes!

 

[SH64]

Most LCDs don't display black and dark colors very well. I'm not sure what you mean with "black/white colors". There is no problem with white or bright colors, it really only affects the dark end.

Sorry by white i meant the brightness issues .. like in some games the brightness is brighter than it should or than CRT's & when i turn it down it gets darker than it should.
i cant seem to get the perfect level (or balance) of the white/black colors i use to get in CRT's. thats generally what i meant to say.
there's also the banding issue Blazkowicz talked about.

 

[London Geezer]

Here... together with Sony OLED, it doesn't get much better than that...