my first acceptable HDR

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Offline fbonomi

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    my first acceptable HDR
    « on: 20 / April / 2008, 11:48:59 »
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    HDR and tonemapping is tricky, it's always too much or too little of it.

    I have very little practice in it and this is one of the first times I am almost satisfied with the results. Still a bit too much artificial sky, but a vast improvement from my previous results.

    It's a three-shots panorama, each shot repeated with thee expositions.

    This might be useful to other newbies like me, so I will post the exact steps I followed to achieve this result.

    I placed the camera in continuous mode, then activated the "TV bracketing in continuous mode" option, and then I used this tiny script:

    Code: [Select]
    @title Continuous:
    print ""
    print ""
    print "Continuous-drive:"
    press "shoot_half"
    sleep 3000
    press "shoot_full"
    gosub "waitpress"
    release "shoot_full"
    release "shoot_half"
    print "Done..."
    print ""
    end

    :waitpress
    wait_click
    return

    Basically, this script simulates the fact of keeping the shutter button pressed until you press any button and shoots a lot of pics :-)

    The process was repeated three times, covering the whole panorama.

    I then selected the 3 most balanced TVs across all the shots (they were TV 320, 650 and 1250), and I renamed the images like this:

    light panorama, made with 3 shots
    hi/a.jpg
    hi/b.jpg
    hi/c.jpg

    middle panorama, made with 3 shots
    mid/a.jpg
    mid/b.jpg
    mid/c.jpg

    dark panorama, made with 3 shots
    lo/a.jpg
    lo/b.jpg
    lo/c.jpg

    I did a "work directory" where I copied one set of images (the light ones):
    work/a.jpg
    work/b.jpg
    work/c.jpg

    Then I stitched the panorama in the work dire (using Panavue, but you can use the one you prefer, the process is the same) and saved the results as "light.tif"

    To achieve identical stitching between the three panoramas, I then copied the "mid" shots in "work", I ran the stitching process again, saving the result as "mid.tif". Same for "lo.tif"

    The idea was of replacing the jpegs and running again the stitching with the same parameters.

    Then, I used photomatix to do the HDR with the three panoramas, and tonemapped it.


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    Offline fbonomi

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    Re: my first acceptable HDR
    « Reply #1 on: 20 / April / 2008, 11:55:51 »
    Almost forgot: this wouldn't have been possible without CHDK because
    1) the "bracketing in continuous mode" option allowed me to have wide bracketing
    2) the script allowed to shoot the three shots without touching the camera, therefore exactly aligned

    This allowed me to stitch the identical panoramas and later to tonemap them.

    Otherwise, if the panoramas weren't identically stitched aligning them properly for HDR proved almost impossible for me.

    The alternate approach (tonemap the individual shots and later stitch the tonemapped shots in a panorama) would be trickier because chosing acceptable tonemapping parameters for the three shots (with quite different light contitions) would beyond my capabilities :-)

    (this is a landscape of the hills of tuscany, with vineyards in foreground)
    « Last Edit: 20 / April / 2008, 11:59:00 by fbonomi »

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    Offline jetzt

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    Re: my first acceptable HDR
    « Reply #2 on: 20 / April / 2008, 11:59:09 »
    Nice results anyway! :D
    How did you manage the moving clouds? Or was there no wind?
    Did I miss something?

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    Offline fbonomi

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    Re: my first acceptable HDR
    « Reply #3 on: 20 / April / 2008, 12:05:44 »
    How did you manage the moving clouds? Or was there no wind?
    No, there was quite a lot of wind and the clouds movement was easily visible.

    but:

    1) within each frame, the continuous mode is fast enough to have a negligeable movement in the clouds between each TV
    2) between the parts of the panorama, there is some movement, but it does not really bother in clouds.

    Also, using the script all the shooting (left shots - center shots - right shots)  was done in about 10 seconds.


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    Offline jetzt

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    Re: my first acceptable HDR
    « Reply #4 on: 20 / April / 2008, 12:10:46 »
    The alternate approach (tonemap the individual shots and later stitch the tonemapped shots in a panorama) would be trickier because chosing acceptable tonemapping parameters for the three shots (with quite different light contitions) would beyond my capabilities :-)
    I think you got really good mapping, would you mind posting your settings or the xml Photomatix saves?

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    Re: my first acceptable HDR
    « Reply #5 on: 20 / April / 2008, 12:36:36 »
    Deleted
    « Last Edit: 22 / April / 2008, 18:28:05 by Barney Fife »
    [acseven/admin commented out: please refrain from more direct offensive language to any user. FW complaints to me] I felt it imperative to withdraw my TOTAL participation. Nobody has my permission, nor the right, to reinstate MY posts. Make-do with my quoted text in others' replies only. Bye

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    Offline fbonomi

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    Re: my first acceptable HDR
    « Reply #6 on: 20 / April / 2008, 14:36:29 »
    Nice results, (and no offense) but I don't really see the need for HDR on an image like this.
    probably yes, but I was experimenting :-)
    And anyway, it was a very contrasted view with an odd light.

    Quote
    Nonetheless, a good exercise in how to do HDR panos.
    Exactly, i am taking it as an exercise.

    Quote
    It looks like you were also using a polarizer, as one area of the sky is unnaturally dark (the 90-degree band from the sun).
    No, no polarizer, as I said it was a really odd light to start with.

    Quote
    p.s. You might want to avoid small f/stops in future projects, you have some nasty sensor dust,
    alas yes.
    the brand new a570 I bought just to play with chdk has this horrible filth. In certain moments (for example during the zoom) you can see it's actually a small hair o fiber-like thing.

    I will have to send it to be fixed but I am too busy playing with the new features to send it to be fixed. Being in guarantee, I am afraid several weeks will pass before I see it back :-(

    And as you say, I try to avoid narrow apertures but with the strong light of these days the only way to do that is to override the ISO to values like 30, and it often gets un-practical....

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    Offline fbonomi

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    Re: my first acceptable HDR
    « Reply #7 on: 20 / April / 2008, 14:41:59 »
    I think you got really good mapping, would you mind posting your settings or the xml Photomatix saves?

    Sure, but i really don't know how useful they can be to other situations...


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    Re: my first acceptable HDR
    « Reply #8 on: 20 / April / 2008, 14:43:17 »
    Nice results, (and no offense) but I don't really see the need for HDR on an image like this. With contrast turned down to begin with, an image like this could have been done with just 3 pano panels properly exposed and the use of a curves tool applied to the final panorama in any editor. Nonetheless, a good exercise in how to do HDR panos.

    You were expecting something like angelreich's deviantART gallery ?

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    Offline fbonomi

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    Re: my first acceptable HDR
    « Reply #9 on: 20 / April / 2008, 15:01:56 »
    You were expecting something like angelreich's deviantART gallery ?

    I quite agree with Barney Fife, I think that (as with any other techniques) HDR should be a mean and not and end. The over-done-ness of those cloudy skies could kill the nicest shot.

    Let's say that I will be content when I will be able to do something like this:
    41/366 sunfisher on Flickr - Photo Sharing!


     

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