Color Calibration for HDR photograph (w/ ND Filter)

Dear community,

Following the work by Stumpfel, Jessi, et al. “Direct HDR capture of the sun and sky.”, I am planning to use Kodak ND 3.0 filter (between the lens and the camera) to capture HDR photographs (sky appearance and environment map from the window) at different times of the day.

As ND filter will bring a chromatic change for a single image, how can we calibrate the HDR photographs with color checker?

Thanks all!

You can try using the macbethcal tool in Radiance for this. I recommend merging from RAW captures converted with dcraw, as it has more consistent color behavior.

If you get good calibration from dcraw without your ND filter, then you probably only need to multiply the red and blue channels by some constants to calibrate again to neutral gray, and macbethcal would be overkill.