HDR (yes something about HDR again)

Discussion in 'Graphics Programs and Photo Gallery' started by doenoe, Dec 13, 2006.

  1. doenoe

    doenoe TPF Noob!

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    Hey there

    i was reading something here on the forum (dont remember what) and it got me thinking. If you shoot RAW, you can change your exposure.........right? So if you take one photo (with the "right" exposure) and the change the picture in your RAW editor. One that makes it more bright and one that is darker. Save each one of them and voila, 3 different exposures. And i thought that should do the trick, take 1 pic and make that 1 pic exposed differently in (for example) PS CS2. So i was all thrilled and stuff and tried it. But then i got this message that there wasnt enough dynamic range to construct a HDR pic.
    So, is it me thinking about this all wrong, is there something else i should do or should i just leave this and take multiple exposures like everyone else?
    Ill just fiddle around a bit more, but would really like to hear any comments on this.
    Thanks for reading :)
    Greetz Daan
     
  2. dewey

    dewey TPF Noob!

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    Using 1 RAW eposure set to 3 different levels doesn't get you much of an HDR image in my trials with HDR - you need a range of images corretcly exposed for the various elements in the frame. No cheating :greenpbl: ;)
     
  3. Mohain

    Mohain TPF Noob!

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    Yeah you can do that and merge them in Photomatix but PS 'merge to hdr' wont let you do it. The results just aren't as good as they are if you take 3 different exposures tho, there just isn't enough info in one RAW. But it can be a good comprimise if want an HDR of a moving image from one shot. Best to 'expose to the right' if you want to use only 1 raw, can add loads of noise.

    Good luck on your experiment :)

    EDIT: A forum buddy from a UK photog sub-forum wrote this guide and it goes into using only 1 raw image for source.

    http://www.petemc.net/hdr-guide/
     
  4. doenoe

    doenoe TPF Noob!

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    Thanks for the replies. I will definetly read the guide, thanks for the link. But ill just be a good boy and do it the multiple exposure way :)
     
  5. Mohain

    Mohain TPF Noob!

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    You've probably seen by now but there are some side by side comparisons of HDR images taken from 1 RAW and 3 different exposures.
     
  6. doenoe

    doenoe TPF Noob!

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    yup, seen those. And there is definetly some difference.
    Stubborn as i sometimes am, i tried it with one pic again. An IR this time. And its the demo version of Photomatix, so try to ignore the watermarks (allthough thats pretty undo-able :) )
    The pic was noisy as................something thats very noisy. Did the PS nois filter and it worked pretty decent. Havent done alot of fiddling in Photomatix, so maybe the outcome can be better (probably). But its just fun to experiment.
    Anyways, its not as good as a HDR with 3 (or more) different exposures, but i still think it looks rather nice.
    here is the pic:
    [​IMG]

    And the normal one
    [​IMG]
     
  7. Alex_B

    Alex_B No longer a newbie, moving up!

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    wrong. exposure is what happens in the moment of shooting ;)

    However, you can rescue and heal wrong exposures to a certain degree.

    And translating this to "HDR", you can tranform one RAW to TIFF, and then tweak brightness and contrast with PS for selected areas of the image.

    However, that way you will not always get it perfect, since still the shadows or highlights will still be exposed incorrectly so that you are in trouble with noise coming up, lack of detail, and simply missing iformation (e.g. clipped highlights)

    So merging multiple exposures can really help here .. but then again I myself am not an expert on this ;)
     

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