Hi Bart, this is interesting. Are you saying there is software that adjusts-out the influence of the orange mask of a colour negative at the scan stage automatically by using the lamp exposure controls of the individual RGB channels (where such capability in the scanner itself allows)? Or is this something the user needs to do manually with each scan provided the software allows it. "Lamp Brightness" in SilverFast, by the way, does allow this level of control, but it's comparatively awkward to use and I'm not convinced it yields better results than the other tools for this purpose. You need to find the right combination of RGB adjustments in the lamp control dialog to exactly neutralize the cast and this isn't a cake-walk. Do you have in mind another scan software you've used for this purpose which does this process more conveniently and yields better results which you've observed?
Hi Mark,
I've owned a number of scanners through the years, and still have a few in operation. Some of those came bundled with Silverfast software, but I found the per scanner licencing and upgrade prices becoming a burdon. I therefore switched to VueScan Pro, and have been using it since many years on all scanners (even ones no longer supported by the manufaturer on new Operating Systems) without the need for re-learning (same user interface for all scanners, save differences in functionality). VueScan intimately operates at the scanner hardware level (after reverse engineering the command structure) and also produces Raw scans. In this case it is really Raw data, directly from the scanner interface, as provided by the scanner hard/firmware. VueScan therefore promotes the saving of such Raw data as a "Digital Negative", thus reducing the need for physical handling of the film material after the initial scan. That allows to benefit from later improvements in the software handling of the Raw data.
Part of the "advanced" workflow for masked negative films consists of determining the mask color of unexposed film (between images of from the leader) once per film (is constant per film, but may vary between batches), and then neutralizing it by adjusting the per channel exposure time (for scanners that allow that, e.g. Nikon Coolscan series). That results in boosting the blue and green exposure times, and as always this reduces the shot noise by maximizing the signal level for the most transparent film areas without clipping (result is maximum S/N ratio, also for the denser parts of the film). In addition it thus neutralizes the mask in linear gamma space (as it is digitized to Raw). What remains is Raw data with absolutely neutral shadow data. Any sensitivity difference between the color channels (non-parallel characteristic curves) will usually be rather linear in linear gamma space, so now it's easy to make the highlight (dense film area) data neutral with a simple levels kind of adjustment in linear gamma.
After these color calibrations, it is relatively trivial to invert and gamma adjust, plus adjust for the film tonecurve. The colors will remain neutral, and saturation can be adjusted at will. VueScan uses a database of film curves to do the tonemapping, but because of the predictable neutral state of the Raw data (can be saved as a TIFF) it also makes it easy to do in Photoshop if one creates one's own film curve.
I suppose Silverfast also offers such a facility, but I have no idea how easy it is to use. With VueScan it's quite simple.
Cheers,
Bart