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Thread: Perception of light and illumination in practice

  1. #21
    Senior Member zoossh's Avatar
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    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by Kit View Post
    Well, take a look at this winner and the comments which followed. Perception of light can be highly subjective but the cake goes to this one. In fact, most of his photos and comments given proved that definition of a great photo can also be highly subjective. http://www.flickr.com/photos/henryleong/1346099311/
    no offence to the photographer of the above link, but can you re-click on the link and tell me if the photo that i'm seeing now is a winning shot of any competition?

    if that is what u mean by winner.

  2. #22

    Default Re: Perception of light and illumination in practice

    This is a very interesting and informative thread.

  3. #23
    Senior Member Kit's Avatar
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    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by zoossh View Post
    no offence to the photographer of the above link, but can you re-click on the link and tell me if the photo that i'm seeing now is a winning shot of any competition?

    if that is what u mean by winner.
    That's exactly the point I'm making. You can't see it as a winner. Neither can I. Try telling that to the 20 odd people who commented. Anything you post that differs from the majority will be deleted.

  4. #24

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by Kit View Post
    That's exactly the point I'm making. You can't see it as a winner. Neither can I. Try telling that to the 20 odd people who commented. Anything you post that differs from the majority will be deleted.
    that's flickr for you.. nothing wrong with that

    a lot of the pools that he posts to are *mandatory* comment groups, i.e. you post one photo there, you have to post 5 to spread the love.

    i usually post to a few of those groups because the admin are my contacts.. must give support

  5. #25
    Senior Member zoossh's Avatar
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    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by Kit View Post
    That's exactly the point I'm making. You can't see it as a winner. Neither can I. Try telling that to the 20 odd people who commented. Anything you post that differs from the majority will be deleted.
    hahaha... i didn't know that. i thought only youtube hate threads do that....

    that's why it is important to build a healthy environment where people can healthily disagree with one another. it takes the adjustment of the mindset of the people commenting and the people being commented on. one dun have to sugar coat, but there is also no need to rub salt.

  6. #26

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by Kit View Post
    That's exactly the point I'm making. You can't see it as a winner. Neither can I. Try telling that to the 20 odd people who commented. Anything you post that differs from the majority will be deleted.
    Well, a winner is defined as the best within its competitive community...

  7. #27

    Default Re: Perception of light and illumination in practice

    We're going off topic already, just a gentle reminder.

  8. #28

    Default Re: Perception of light and illumination in practice

    I am really interested to know more about this sort of "art"/ "light"/ "design" knowledge, especially those that got to do with photography.

    If possible, can anyone please share it? I believe that it would help in one way or another in my learning of photography.

    Thank you to the TS for this great information and also to those that contributed to further additions of this topic.

  9. #29

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by photobum View Post
    Furthermore, mindless claims like “HDR increases the dynamic range of your photographs” are not true. HDR does nothing of that sort. What it does is to squeeze (compress) the dynamic range in the scene so that it fits into what your photograph can show.
    actually, HDRI does increase the dynamic range that can be represented in an image... HDRI is basically an image format that allows a wider dynamic range, beyond the 11~13.5 stops that even the best cameras and film can capture, or even the 14 or so stops that the eye can see at once... basically, you can fit as many stops as you can merge together in software (of course, YMMV)... but it is only that, a file format, and what's more, it cannot even be displayed on any screen that is commercially available for the very simple reason that there are no commercially available screens that can display that wide a dynamic range... what we can see on the screens are tone mapped representations of the actual HDR image, either squeezed into what may be represented on screen, or some of it might become blown highlights or blocked shadows... and HDR images are not saved into regular TIF files or JPGs but in specialized HDRI formats which maintain the large amount of data of the wide dynamic range as well as the as yet not permanently applied tone mapping... one of these formats, as far as Photoshop is concerned, is the 32bit floating point PSD format (not the usual 8bit or 16bit discrete PSDs)...

    working with HDRI in Photoshop Extended would more easily illustrate the above point that the HDR format allows a wider dynamic range than can be represented on a screen... when doing such work (donno if it works in other software... I'm a Photoshop person ) on Photoshop Extended, one has the option to use a filter called "Exposure"... what this does is vary the "exposure" that is represented on screen by varying the part of the HDR image that should be represented on the screen, all without actually doing the destructive manipulation that using curves or levels would cause which would show up as torn up histograms... it just changes the "exposure" that is to be displayed on the screen... and if doing it on an adjustment layer, we can even mask out certain areas and thus have different areas of an image "exposed" to different amounts so that one can brighten up dark areas or darken bright ones, all without working destructively on the image... to output the image to a more accessible format like JPGs or TIFs, we have to "burn in" a tone map, converting the wider dynamic range into something the common formats can accept... but these are now no longer HDR images but only low dynamic range images...

  10. #30

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by LittleWolf View Post
    What I am saying is that, if you require the order of "brighter than" or "darker than" to be preserved in your image, the only way to convert a high dynamic range image to a lower dynamic range image is to reduce the contrast, i.e. create a "flat" image. The so-called local tone-mapping operators used in HDR software (which is what most people mean when they talk about "HDR image") do not preserve the order of tonal values.
    and as a follow up to what you have said, to create a realistic looking image from a HDR composition, one would have to adjust the tone mapping applied such that the resulting luminance values in the image look as if it is logically possible in real life... whether they are those values in real life or not is immaterial...

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