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The importance of Blacks - examples

Discussion in 'Plasma TVs' started by Rahmorak, Sep 7, 2005.

  1. Rahmorak

    Rahmorak
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    Howdy,

    OK most people are aware that when they buy a plasma they want decent blacks, however black level affects a lot more than just how dark the space in Star Wars looks and I wanted to try and show just how important it is.

    Generally speaking the lower the level of black in an image the punchier, more 3-dimensional the image is. In the case of displays this black level is obviously in part determined by how black the panel can go and in part by the user settings used (e.g. brightness/contrast etc).

    It is for this reason that calibrating your TV/Plasma/Monitor etc is so important.

    So, I decided to knock up a few examples of how adjusting the black level can affect a still image, in these examples Pure black is 0, Pure white is 100. With a value of 12 the darkest part of the image would look dark grey, whereas a value of 0 means that it would be pure black.

    Important: depending on how your monitor is configured you may lose a lot of black detail in the sample images, http://www.normankoren.com/makingfineprints1A.html provides an excellent start for basic calibration of a monitor.

    Image 1 - Grey-blacks (black at approx 12)
    On it's own this image probably looks OK, but a bit flat.

    [​IMG]

    Image 2 - Pure blacks (0)
    Let's see what happens when I bring the blackest point closer to 0 (this is the shadow under the wooden chest).
    The image starts to 'pop' and the colours become more saturated.

    [​IMG]

    MUCH better!

    Image 3 - Clipped blacks
    In reality we can often get away with losing some black detail (e.g. pushing the contrast higher),
    without impacting on the detail we can make out. e.g.

    [​IMG]

    For me this is the best of the 3 images. The colours are richer, more vibrant and yet
    I can still make out the details on his socks, the inside of his trouser leg etc.

    Image 4 - Over-Clipped blacks
    However, if we boost the black level too much, we end up losing detail, e.g.

    [​IMG]

    Yuck, his back trouser leg has now got almomst no detail in it and it starts to look very artificial.


    Let's add a black border and see how it looks with a more subtle black difference.

    Image 5 - Dark blacks (6)
    In this image we have got good black, and on its own we would probably be happy enough with this.

    [​IMG]

    Image 6 - Pure blacks, slightly clipped
    In this image we have got a pure black border and actually boosted the amount of
    black to the point that some detail is lost without it being obvious.

    [​IMG]

    A much better image, almost 3d compared to the previous one.

    OK, this is a pretty basic example as there are many factors that contribute to the final image (such as your screens brightness, amount of noise etc) but I have hopefully given some ideas for why correct/decent black level is so important to a good picture as in all cases I only adjusted the black point.

    Rahmo
     
  2. RHCP

    RHCP
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    Brilliant!

    Thanks for putting the time in to do this Rahmorak!

    I've always wondered why people go on about blacks all the time!

    Makes sense now :thumbsup:
     
  3. UKseless1

    UKseless1
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    Please excuse me if I'm showing my ignorance here. Perhaps the demo is wasted on me but without you pointing out where the faults were in these images, I would have been perfectly happy with them.

    It's an interesting subject though cos while I could spend hours "calibrating" my screen to get the result you demonstrate, it only takes a dodgey source or badly reproduced DVD or poorly shot movie to blow all that effort away. Again perhaps I don't have an eye for this type of thing.
     
  4. RHCP

    RHCP
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    Ramorak is trying to show us how to get the best out of our equipment. I couldn't see the difference with the little boy at first until i read the comments pointing out the clarity.

    If you don't want to get the best out of your equipment then this demo is wasted on you and you can go on living in ignorance.
     
  5. UKseless1

    UKseless1
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    Please don't misinterpret my post as taking a swipe at the effort that Rahmorak has made in providing a demo of this. I think it's interesting and worth discussion.

    Striving for this level of perfection generally leads to having your set ISF'ed and I've often wondered what the before and after would be like and while I know this one is about black levels if this is an example of what the before and after might be like, then I can't say that I would see enough justification in spending the money on professionally calibrating a screen.

    I'd be interested in what some of the more experienced Forum members think of this as well.
     
  6. neilbutler

    neilbutler
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    I too am thankful for the demonstration, it does go some way to explain what everyone bangs on about!
     
  7. Neil F Holland

    Neil F Holland
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    Most illuminating indeed... of course what we see will inevitably be governed by both our own visual capacities and the computer screens we're looking at right now, ambient lighting etc.
    :cool:
     
  8. UKseless1

    UKseless1
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    Ah - funny the difference a monitor makes. I was viewing Rahmorak's post from a Laptop display earlier and could not see the effect in the pictures above. I'm now looking at them from on a Dell Desktop CRT and I can more easily see what is being demonstrated.

    Nice one!
     
  9. Rahmorak

    Rahmorak
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    Yep, that was part of the point really, many people ARE happy with the current image/settings they have and that is great, just as many people are happy with a point-and-shoot camera. However what I was trying to show, in a very crude manner, is why black level is so important for people who want the best image quality.

    That said the reality is slightly more complex. A screen with perfect blacks but a contrast ratio of 500:1 would be pretty dreadful, so brightness/contrast ratio all play an important part as does the quality of the de-interlacing/scaling, colour depth etc. etc.

    So, blacks won't be the only factor when buying a panel (but they should definitely be an important one) and that is why you might prefer a Pioneer 505 (for example) over a Pioneer 50PHD7.

    The ideal is to get excellent blacks, contrast ratio, colour depth, brightness, scaling, de-interlacing etc. all in one package. Until that happens though black level is a very important part of whatever panel you buy. :)

    Rahmo
     
  10. rooster-x

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    Yeah I too am looking at an LCD screen and as you scroll the images up they go from dark to bright, oh whoa, where is my CRT! :eek:
     
  11. Rahmorak

    Rahmorak
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    :)

    Although I used a Lacie Blue IV monitor in sRGB mode to generate the images they will look radically different on just about every other monitor, e.g. if the contrast is too high and the brightness is too low there will be a lot of image detail lost in the sample images.
    For that reason I included the link to a monitor calibration page but of course everyone will still see something slightly different.

    I am using a DELL WUXGA+ TrueLife screen to write this (laptop TFT screen with 1920x1200 res) and I tested the images on here before posting but ultimately most of it is beyond my control. :)

    I am glad some have found it useful though.

    Cheers
    R
     
  12. Piers

    Piers
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    Having been away for a few days I came home tonight and started reading this thread. A reply to UKseless1 about how much more than just setting black level an ISF calibration involves was about to be composed! I also viewed R's photos on a CRT and the effect of having black level incorrectly set was subtle to say the least. I have now switched to my laptop and the differences between the photos is huge.

    What, I think, this shows is that even if you think your monitors are calibrated (both my CRT desktop and TFT laptop are calibrated) it means little unless they are top quality. I use both screens for word processing / spreadsheets / web browsing etc, not watching videos. They are both good for what I use them for - clearly they are not good for video material.

    I watch video material on either a plasma screen or a projector. It probably won't come as a surprise that both are ISF calibrated!

    The ISF process includes accurately setting all of the "user controls", not just black level but also white level, colour saturation, sharpness etc. Each of these can have a profound effect on picture quality and on a large screen will be much more obvious than on a computer monitor. ISF then goes much further, into settings that may not be available in user menus, such as gamma, colour temperature and colour management.

    Even if a user cannot see the difference between optimally set black level and black level a fair bit out (per R's posting) the chances are that they will see a big difference between all of the controls optimally set versus all of them a bit out.

    I have had a number of sceptical customers - "not sure that this is going to make much of a difference but all the guys that say it is worthwhile can't be wrong" - all appeared to be converts once the job was done.
     
  13. Rahmorak

    Rahmorak
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    Yep, I was only touching on one facet of image adjustment in the above examples (which may need to be made more extreme) but if you think of the difference black level alone can have then when you factor in additional factors such as Piers mentioned you can see how an image would be transformed.

    In the second set of photos some of you may have noticed a green tint, that is because I was aiming for a cross-processed feel for the original photograph. However if I (very crudely) correct the white balance/colour temp then you see something very different, e.g.

    [​IMG]

    Now, while I wanted the 1st for a photo I certainly wouldn't want to watch a film like that. And that is just one small part of an ISF calibration.

    Cheers,
    R
     
  14. DFL

    DFL
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    bump.

    Great thread. It goes up there with the pictorial explanation of posterization, solarization et al in another thread. Thanks Rahmorak.

    If this goes to represent what Panasoinc "blacks" are compared to "the rest" my decision to get a PHD8 is being made easier. Although I was very intereseted in the bumped thread re: Pioneer MXE-1 and the new board giving pixel perfect pictures. Anyway I digree. Thanks R.
     
  15. RHCP

    RHCP
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    Can you give links to the other pictorial explanations?

    Cheers :)
     
  16. DFL

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