[Radiance-general] Tone mapping for animation

[Guglielmetti, Robert]

Yep, it's a tonemapped jpg that retains (in a lossy way) the HDR info, so you can share these with people sans HDR image viewers and still retain backward compatibility (and enjoy a smaller file size). The paper is here:

http://www.anyhere.com/gward/papers/cic05.pdf

I do not know exactly what operator is used by hdr2jpeg...

- Rob


From: David Geisler-Moroder [mailto:david.moroder at gmail.com]
Sent: Tuesday, October 22, 2013 9:50 AM
To: Radiance general discussion
Subject: Re: [Radiance-general] Tone mapping for animation

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<mailto: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 Incorporated

www.visarc.com<http://www.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<mailto: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 Incorporated

www.visarc.com<http://www.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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