Poor Definition in Shadow Areas
You scan a transparency film such as Kodachrome containing a high contrast scene expecting:
but despite your best efforts you get:
where the shadow areas have blocked up.
Cause: Shadow details are concentrated in a narrow range of intensities, often an indication of a scanner with a Dmax (the maximum density it can discern) too limited to cope with the film type.
Comment: Unless you have a lot of expertise in reading histograms and applying curves, obtaining something like the former image from the latter image can be difficult, and that assumes your scanner's Dmax is sufficient to define the shadow densities accurately. A scanner with insufficient Dmax will produce shadow areas speckled with noise and lacking in tonal separation. The latter image was created with an older scanner which has a more limited Dmax.