I have started to scan my film, black and white, most often Tri-x. I want to increase the information in my files, using several exposures in Vuescan. Mostly to get better gradients, like increased apparent bit depth? More so than increase the dynamic range. Is this possible?
First of all, negatives like TRI-X usually do not have a high enough optical density to create Dynamic range issues for most scanners. So you do not need to resort to multiple exposures per scan line, or multiple image scans, for increasing the dynamic range of the scan. In fact, you run a risk of mis-alignment due to film expansion during the scan, caused by an increase in temperature. That would create a risk of mis-registration of the subexposures.
I scan in 48bit raw tiffs, using a Plustek with vuescan. My histogram has a lot of information, but the tiff lacks any ability to adjust exposure and just using a simple levels adjustment's middle pointer, the image gets crushed rather quickly.
VueScan will produce either 16-bit per channel grayscale or 48-bit RGB image files, and they are already inverted for normal output viewing. It can even produce 64bit RGBI data files from scanners that have an IR-light dust detection feature, but that won't work with silver based film, because silver is opaque to IR light. Only Chromogenic B/W film could benefit from that. The benefit of scanning B/W film as RGB is that you can later average the three channels which will reduce noise. VueScan has some controls (Black/White-point, s-curve, and a brightness control) for postprocessing of that data, but it's obviously only a small sub-set of what e.g. Photoshop can do with the output file.