Hi Jill,
I'm thrilled to be so helpful. Usually I'm the one asking for help.
Ok, here's what my scanner help says about gamma:
"Image Gamma
Gamma values are another measure of a colors brightness. The higher the gamma value for a color, the brighter the color will be. All gamma values changed here directly affect the image and will be saved along with the image unlike monitor gamma values.
Gamma values always follow a smooth curve; adjusting the gamma affect the entire tonal range for that color."
Not all scanners have the ability to adjust the same way mine does so I can't say how or what you do to get advanced or enhanced settings on your machine. Mine shows a historgram, levels and gamma for each channel plus a black channel. If you can find gamma listed in the software on your scanner diolog box help file it should tell you how to work with it. I really have a cheap low end Plustek scanner thats about 3 years old but I am lucky in that it has a pretty good software to allow me to tweek before scanning. If yours allows you to adjust the gamma for each channel like mine then what I do is move the slider up to 1.28 for each channel and for the black I might go up to 1.55. I have gone up to 1.85 and gotten a good detailed scan if the subject was wearing all black. I then had to darken and set contrast in photoshop but at least you could see the details in the shadows.
Let me know what you find in your scanner info.
DJ