And though, UnSharp Masking comes from that era (sandwich a blurred low-contrast negative to your original, that does it)!
Ditto!
I've been using PKS for a couple of years, mostly for output, and it's doing a great job. Now on version 2 of course.
YES! The quote above is exactly right. Create a duplicate of the background layer and rename as "Mask". Desaturate the Mask layer, invert it to negative and then change the blend mode to "overlay". Enlarge the image to 100% and look at the horizon line or other high contrast area. This is important for the next step. Use Gaussian Blur to reduce resolution degradation of the image by the Mask layer, yet at the same time avoid halos on sharp contrast boundaries such as skylines. Low amounts are usually best. You will then start to notice the increase in sharpness. Adjust the opacity of the Mask layer as required and you now have an "Unsharp Mask".
This is the digital version of a procedure I have used quite extensively when printing 4x5 B&W negs in the darkroom, except for the opacity control of course. The darkroom version of opacity control in this procedure is actually "contrast control". You would be printing the image at a much higher contrast than normal and the unsharp mask increases edge definition. It's really quite amazing how much the perceived sharpness is increased. And of course small details are enhanced as well with this procedure.
OMG! I think my age is showing again. Just a little exercise to show how unsharp mask actually works. Break it down into its separate part and there it is.
Have fun.
Gary