[Radiance-general] Tone mapping for animation

[David Geisler-Moroder]

Hi Jack, hi Lars,

thanks a lot for the quick response!
Jack, your second hint exactly did what I was looking for. I tried to use
pcond first, but didn't think of the possibility to use a histogram...

Sorry, if my description was somehow cryptic, but you exactly found what I
wanted...

Just for information: the pfilt exposure corrections do not help in my case
because the tone-mapping that is done in the HDR2LDR conversion (with
hdr2jpeg / ra_tiff or similar) does the tone mapping for each single frame
independent from the other images. (But maybe I just got something terribly
wrong here...!?)

Thanks!
David



2013/10/22 Jack de Valpine <jedev at visarc.com>

>  Hi David,
>
> I am a little unclear on what you want to accomplish but here are a few
> thoughts.
>
>    1. time series animation with constant exposure on successive frames -
>    use pfilt -1 -e [constant exposure setting] for each frame
>     2. time series animation with tone mapping function on successive
>    frames - use pcond and phisto, phisto will compute a histogram across a
>    series of frames pcond can then use the results from phisto to tone map the
>    frames according to selected tone mapping operator, there is a an example
>    in the man page for pcond
>
> I think that maybe where I am confused by your description is that since
> Radiance output is already HDR, setting exposure is really a post process.
> I think that what you are looking for is the second option that I describe
> above.
>  Not sure if this answers your questions, but perhaps gives you some
> things to look into.
>
> Best,
>
> -Jack
>
> --
> Jack de Valpine
> President
>
> Visarc Incorporatedwww.visarc.com
>
> channeling technology for superior design and construction
>
> On 10/22/2013 9:45 AM, David Geisler-Moroder wrote:
>
>  Hi all,
>
>  I have a question concerning the tone mapping procedures implemented in
> the Radiance tools.
> For an animation of a full day I would like to get something similar that
> a camera would do that just takes a picture every 5 minutes with the same
> settings (exposure time and aperture). Rendering the images for every 5
> minutes is not a problem, however, I stuck when trying to convert the HDRs
> to some tonemapped images. As far as I got it, In ra_jpeg/hdr2jpeg no
> exposure can be given at all, in ra_tiff/ra_bmp only relative exposures can
> be applied.
>
>  Thus my question: is it possible to explicitly set the exposure used in
> the tonemapping process with any tool in Radiance?
>
>  Thanks in advance!
>  David
>
>
>
> _______________________________________________
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>
>
>
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