[Radiance-general] Display of time lapse at constant brightness

[Andy McNeil]

You could also use phisto to create a luminance histogram from all your
images and tone map your images using pcond with the all image histogram as
input.

phisto frame*.hdr > allframes.hist
pcond frame0001.hdr < allframes.hist | ra_tiff - frame0001.tif

When there's a wide range of illumination conditions I find that pcond with
the histogram works best to preserve visibility and maintain consistency
between frames.

Andy

On Sat, Oct 3, 2015 at 5:45 AM, Chris Kallie <kallie at umn.edu> wrote:

> You can use the -e option in pfilt to adjust by a constant. Instead of
> using +0, you can use a value without the + symbol that is a fraction of
> the EXPOSURE value in your header file. -Chris
>
>
> On 10/3/15 8:21 AM, ascendilex | Wouter Beck wrote:
>
>> Dear Group,
>>
>> I'm trying to display a series of Radiance renderings as a time lapse
>> animation.
>>
>> I convert (pfilt -e +0 -r .6 -x /2 -y /2 filtered) hdr-images via
>> ra_tiff and the resulting tifs are combined into an animated gif via
>> (ImageMagick's) convert -delay 200 -quality 100 *.tif time-lapse.gif.
>>
>> Each image represents a view of an atrium 1 hour apart.
>> The indirectly lit walls of the room that contains my view point get
>> displayed darker as the atrium scene brightens up.
>> In absolute terms one wall has a luminance of 15 cd/m2 at 9:00. That
>> same wall is 29 cd/m2 at 12:00, yet when displayed (using ximage) it
>> appears darker.
>> Exposure times in the headers are of course quite different:
>> vp-A-092108.00.pic:EXPOSURE=3.008155e+00
>> vp-A-092112.00.pic:EXPOSURE=3.957302e-01
>>
>>
>> Basically I want the tone mapping according to a constant (perhaps log)
>> scale for all images.
>>
>> How can that be accomplished?
>> (Looks like falsecolor could do this if it also had a greyscale palette.)
>>
>> Best regards,
>>
>> Wouter
>>
>>
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>
>
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