The value range of HDR image in ground truth

gabrieleilertsen / hdrcnn

HDR image reconstruction from a single exposure using deep CNNs

https://computergraphics.on.liu.se/hdrcnn/

BSD 3-Clause "New" or "Revised" License

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The value range of HDR image in ground truth #33

Closed ChuangbinC closed 4 years ago

ChuangbinC commented 5 years ago

Hi, I find that the value range of the HDR image in ground truth set is seem no like absolute lumination in real world because the max value of the img_0001.exr is only 14.625. What is it mean and what is the unit of the value?

The ground trurh is from this

Thanks!

gabrieleilertsen commented 5 years ago

Hi. There is no unit to the HDR values. The images are scaled to have a certain fraction of pixels larger that one. They are linearly dependent on luminance, i.e. for HDR image I the luminance is a*I cd/m2 for some unknown scaling factor a.

ChuangbinC commented 5 years ago

@gabrieleilertsen Thanks for your reply. And I have another question that whether you use some HDR reconstruction methods such as Debevec's to build your ground truth.

gabrieleilertsen commented 5 years ago

I used hdrmerge for the HDR images I captured myself (images 49-89 of the provided testset). The other images, and training images, come from various online resources which were already merged.