[Radiance-general] Tone mapping for animation

[David Geisler-Moroder]

Hi Jack,

I guess Greg is the only one to answer that question.
However, I guess some tone mapping has to be done as the HDR-JPG format is
backwards compatible and all viewers that read JPGs also read that. So
somehow they need to get get the tonemapped information...

Cheers,
David


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

>  Hi David,
>
> Great, glad it helped!
>
> I have not used the hdr2jpeg utility so I am not really sure what it does.
> My impression is that it converts to a jpeg that contains hdr information.
> I do not think that it does tone mapping though. Perhaps others can weigh
> in...
>
>
> Best,
>
> -Jack
>
> --
> Jack de Valpine
> President
>
> Visarc Incorporatedwww.visarc.com
>
> channeling technology for superior design and construction
>
> On 10/22/2013 11:14 AM, David Geisler-Moroder wrote:
>
>    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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