Iliah Borg wrote:
Such shots are done using tripod and remote, so if user (or scanin) samples one chart all other locations are the same. I prefer manual sampling (like it is done in RPP) because that allows to avoid any imperfections right from the start. It seems that profiles with manual sampling go easy to 6dE max, while with scanin they are usually about 12 to 20 dE.
I'd be interested to have a sample that shows such a difference, as scanin should work better than that.
I would start with a merge utility that re-calculates spectral reference for each individual .ti3 file based on the exposure of grey patches (around neutral grey)
Right, this sounds much like HDR image merging. It is also a bit outside the scope of the next release :-)
filters veiling glare can reach 2/3 EV easily when shooting a chart. Adding a simple black trap (hole) to a chart allows for a good estimation of veiling glare.
That would only work for a specialised chart though. I wonder if there is a more general way of estimating flare. Is it reasonable to assume that flare decreases in line with everything else if the exposure is reduced ? Graeme Gill.