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Thread: HDR: How's it done?

  1. #1
    neverhood311's Avatar
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    HDR: How's it done?

    So, it may appear from the title of this thread that I'm just another person who's seen some of the stuff that HDR can do and wants to try his hand at it.

    Well, you're partially right.

    Though I have been dabbling in HDR for a couple of years now and I consider myself fairly competent in doing so.

    What I'd really like to know is how it's done--behind the scenes.

    I'd like to know the inner workings of a 32-bit photo and how the information should be organized in the file. I'd like to know how to take 8-bit images and compile them into a 32-bit image. Once I get to that point, I'd like to test out and implement a number of tone mapping algorithms.

    Basically, I'd like to write my own HDR compilation and tone mapping software.

    I've searched around a bit and the only answer I can seem to find so far is that 8-bit images are compiled to 32-bit images using Photoshop......which is fine for most people, but doesn't help a programmer.

    Does anyone know where to find more information about how it's actually done? Even semi high-level concepts or algorithms which I can later implement in C++? I can't seem to find much.

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    FrankMi's Avatar
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    Re: HDR: How's it done?

    Hi Justin, because there is no "one-for-all" universal solution to map high dynamic range images down to a viewable/printable image, there is also not a single algorithm.

    Perhaps your best bet is to research the various articles on the internet that concern the comparison of tone mapping algorithms, such as the ones at http://www.frank-durr.de/tonemapping...tml#ref-fattal and http://wiki.panotools.org/HDR_Software_overview, but these are only research starting points.

  3. #3
    neverhood311's Avatar
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    Re: HDR: How's it done?

    Thanks for the links, though I still can't seem to find information on how to compile bracketed 8-bit or RAW images into a single 32-bit HDR image. I think I want to learn that before I start writing a tonemapping program.

  4. #4
    FrankMi's Avatar
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    Re: HDR: How's it done?

    Quote Originally Posted by neverhood311 View Post
    Thanks for the links, though I still can't seem to find information on how to compile bracketed 8-bit or RAW images into a single 32-bit HDR image. I think I want to learn that before I start writing a tonemapping program.
    Hi Justin, if you can't locate the specific information you need on the internet, then you might want to try contacting Photomatix or any other HDR software provider and see if they would be willing to point you in the right direction. They could all refuse but if even one helps, you'll be closer to your goal.

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    Re: HDR: How's it done?

    Take a look at Picturenaut - they seem quite keen for people to write for it, and might be quite helpful...here's the url;

    http://www.hdrlabs.com/picturenaut/sdk.html

    HTH

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    Re: HDR: How's it done?

    Justin, I've just done something I should have thought of earlier - I Googled it, using these terms;

    "Open source" +HDR

    Here's the search;

    http://www.google.co.uk/search?q=%22Open+source%22+%2BHDR&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GBfficial&client=firefox-a

    It should work in other browsers - does in Opera, at least.

    I hope that there's something of use there...

  7. #7
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    Re: HDR: How's it done?

    Search for Gauss-Laplacian pyramids. My Implementation is at http://www.adptools.com/en/idrmyimage-description.html

    Filip

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