The negative was scanned as a negative (left) and converted to a positive image with a single "Invert" keystroke in Photoshop.
To a computer, positive and negative images are inverted by simple arithmetic performed on each pixel - essentially subtracting 255 from each value and eliminating any minus signs.
The leftmost image resulted from applying "Adjust Levels - Auto" and corresponds to the traditional darkroom task of finding the proper paper grade or variable contrast filter setting to encompass both low and high values properly.
The rightmost image represents a somewhat more difficult traditional process - finding a paper which has the proper "response curve", long or short toe, etc.. Adjusting the shape of the response curve is done by the manufacturer by changing the formulation of the paper emulsion. The photographer has very little control over this characteristic and must experiment with different paper / developer combinations to achieve what is accomplished here with a "slider" control in Photoshop.
This is the same image (file) as # 4 above it except for the application of "Unsharp Mask". The scanning process generally introduces some softening (seen in the images above) which can be corrected with either Sharpen Edges or Unsharp Mask, but care must be taken not to over sharpen.
As with the Adjust Levels controls, Unsharp Mask provides so many options that finding the proper one is a non-trivial exercise. What looks good on the computer monitor may not be optimal for your printer or film recorder, indeed some "over sharpening" is often in order when preparing files for output devices.
The application of the very sophisticated controls IS a creative artform which can surely test the photographer's vision and skill.
No attempt has
been made here to "finish" the print. It is now time to get out the
dodging and burning tools (available in Photoshop) and/or the
potassium ferricyanide (which is not). Oh, well, maybe just a bit of
fiddling around