Variable white clipping points in raw file

[heckflosse (Ingo Weyrich)]

@ggbutcher

In rawproc, I recently included a mode to set the white point to the actual data maximum from all channels, and an option to set it at the minimum of the channel maximums to obliterate the whitebalance shifting

I prefer knowing the right value. For example RT capture sharpening does not sharpen the pixels close to a clipped highlight, because the data used to apply the deconvolution is not linear if there is a clipped highlight close to a pixel. To do that, knowing the correct white level is important.

[ggbutcher (Glenn Butcher)]

Oooh, learning… my thought with doing that was to just go to the top of the data in one operation, instead of setting the white point then applying exposure comp to scale the data to white. Does highlight reconstruction have a similar consideration?

I do have another mode to apply the metadata values, but I need to consider alternatively looking them up in camconst.json

[CarVac]

Highlight reconstruction wants cleanly clipped pixels, no clipped data hanging out below the white point.

I haven’t tried looking in the camconst.json for the D800 to see if it has per-channel white clipping points…

[Waveluke (Pat Cunn)]

I noticed similar weird behavior of multiple apparent ‘clipping points’ in the bmpcc original raw files, as I described and documented with tests here about a year ago.

FPN near/at clipping highlights BMPCC

In implementing proper support for DNG files from the Blackmagic Pocket Cinema Camera, there was a discussion on setting proper white points. I noticed an issue that might be complicate white point accuracy, some fixed pattern noise (FPN) at or right before clipping. I am not asking for a solution to the noise as an end user, as there are many ways to solve the issue, from dual demosaicing in RT to all the blur and masking tools in Davinci Resolve and Blackmagic Fusion, as well as not being a…

[CarVac]

I’m encountering this issue again, having made no progress since it last came up, and I think what we need is a) a database with a superset of the data the different editors want, and b) scripts that autogenerate the desired files for each existing editor.