When you stitch large format with a comparably small sensor it's not sure that you even have the optical center in the image. And if you use a center filter on the LF lens the optical center may actually be slightly darker than a bit out from it. Another problem is that the MF CCD have color casts in their own, so if you put the optical center in a different position of the sensor you may get a slightly different response. That error should be relatively small though.
Hi,
An LCC is formally nothing more than a normalization of channel response across the image in linear gamma space. It should not influence White balance for that frame. It uses the brightest area of each channel of an image (wherever it is, center/edge/corner/elsewhere) and normalizes that to 1.0 (R=G=B=1.0 or 100%). It then calculates the percentage of relative darkening across the image area for each channel. It then divides each channel by the darkening percentage for that channel (e.g. 90% brightness gets divided by 0.9, therefore boosted by a factor of 1.11), thus creating a uniform response across the image. That normalized data is then used for demosaicing, given a certain user input for White balance.
Because it uses the brightest spot in each blurred channel, it should not change the white balance at that spot. That does mean that an actual White balance difference between shots (light has changed or sensor responds off-neutral at the brightest spot) is maintained. So with extreme shifts which leave the brightest spot off optical center, the white balance will remain shifted.
I don't know how C1 calculates the reference white from the LCC, it's something one could test, and certainly interesting for those stitching within a large format image circle.
(In Lumariver HDR I've solved it in the way that you can select an "anchor LCC" so the reference white will be exactly the same for all frames.)
Nice, especially if applied before demosaicing, although it may increase noise a bit. It will still help if applied after demosaicing (as a kind of color correction), but at slightly reduced color accuracy, although probably still better for uniform color than without it. Post-processing is often about trade-offs.
Cheers,
Bart