Hmm - pre-appending with a 6 didn't do the trick.
It seems like hdrgen really wants a 3rd order polynomial (no matter what I put
into the .rsp, hdrgen overwrites it as such), and I'm not too sure how to
translate the 5 values for the R, G, and B channels generated by Photosphere.
As another data point, the other camera curves in my Photosphere preferences
file have a variety of values, either 4, 5 or 6 for each channel, depending on
the camera.
As a work around, I can apply a multiplier to the .rsp that hdrgen makes, and
that gets me pretty close. But I'd also love to know if there's a more direct
way to translate the Photosphere data into hdrgen friendly data.
Thanks all -
Mike
On May 13, 2013, at 12:14 PM, Axel Jacobs wrote:
> Hi Michael,
> > I'm trying to use hdrgen with a response curve created by photosphere.
>> For the image, I have calibration points measured with a luminance
>> meter, and when I make the hdr with photosphere, I get an accurate
>> luminance measurement, but hdrgen gives me a value that's consistently
>> ~10% higher. This is surprising as (I think) I'm using the same response
>> curve for each process.
>>
>> Here's my hdrgen command:
>> hdrgen -o ../01.hdr -r canon_5D.rsp -q 100 -f -g *.JPG
>>
>> Here's what I put into canon_5D.rsp:
>> 7.135383e-03 -3.556814e-02 2.441168e+00 -5.786777e+00 4.462320e+00
>> 4.543790e-03 3.363440e-02 1.917460e+00 -4.660105e+00 3.792747e+00
>> 3.956902e-03 3.244581e-02 1.827308e+00 -4.505138e+00 3.729707e+00
>
> The first number in each line in an RSP file is the order of the polynome.
> Since it is missing in the RSP above (the one you hand-crafted from the
> Photosphere response), hdrgen deems it invalid and overwrites it with a new
> one. Try pre-pending a '6 ' to all three lines. hdrgen should than be happy
> and use the RSP that you supplied, rather than generate one from scratch.
>
>> Here's canon_5D.rsp after hdrgen is run:
>> 3 1.49643 -0.979 0.486712 -0.00413976
>> 3 1.44009 -0.884479 0.448854 -0.00446749
>> 3 1.46366 -0.875187 0.414554 -0.00303108
>>
>> And here's the response curve from Photosphere:
>> "Canon"|"Canon EOS 5D Mark
>> II"|"v.0"|{7.135383e-03,-3.556814e-02,2.441168e+00,-5.786777e+00,4.462320e+00}|{4.543790e-03,3.363440e-02,1.917460e+00,-4.660105e+00,3.792747e+00}|{3.956902e-03,3.244581e-02,1.827308e+00,-4.505138e+00,3.729707e+00}
>>
>> Am I missing any hdrgen options, or perhaps making an error in my .rsp
>> file? Thanks in advance for any insights.
>
> More info here:
> http://www.jaloxa.eu/webhdr/calibrate.shtml
>
> Cheers
>
> Axel
>
>
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