We have yet another good trick left for troubled times. Sometimes the preview shows the image is simply too dark or too light, especially when scanning negatives or slides. Prints are more consistent, because the photo-finisher helped get them correct, but film varies considerably with our camera exposure. When we see the preview image is too dark or too light, and when all of the histogram data is greatly shifted to one side, (not at all well centered in the histogram), then often the Exposure Control will be of great help. (Many scanners have an automatic exposure control, and some have a manual control).
In ScanWizard, for positives (slides and prints), this is found in the first toolbar icon, the BCE control (Brightness, Contrast, and Exposure). The Brightness and Contrast controls there are NOT of interest (the histogram tool is better), but in problem cases, often the Exposure control can help center the histogram data, after which we can deal with it normally.
This is a Fujichrome slide at the Matterhorn in the Swiss Alps. We're very high, the peak is nearly 15,000 feet. Fujichrome has exaggerated color anyway, but something seemed different at altitude. These were all way off and very saturated.
The Upper Left image is the BEFORE Histogram (after Reset). This is what I mean by the histogram data not being centered well in the histogram. It might be because we dont have any light tone values in this image. Nope, like that's snow, and snow should be white. So in this case, our slide exposure is simply too dark.
The Upper Right is the Exposure Control setting for slides, and the Lower Left is the AFTER Histogram showing the histogram after the Exposure Control adjustment. Notice we have not even touched the B&W Points yet, and actually there's little need now, but that is not necessarily typical.
Prints don't usually need the Exposure Control, normally. However, the need for the Exposure Control is the norm for negatives, they vary drastically (well, mine do anyway <grin> ).
ScanWizard's Negative mode has its own Exposure control added to the Color Tints tool, and it's different for negatives. Negative mode also has a few film types (Agfa, Kodak, Fuji, Konica) in the Color Tints tool, which balance out the color of that companies orange mask.
Exposure is easily the most important control for scanning negatives.
Tend to it FIRST. 1) Reset, then 2) Exposure if needed, then 3) all the
rest. Slides also vary much more than prints, and might need exposure
adjustments too. For prints, normally adjusting the B&W Points is