This is a somewhat complex subject. There are, probably, as many different opinions on this topic as there are people. Sharpening, like "color correction" is very subjective. So... what I'm about to put forth, take with a grain of salt. After all, I am an "amateur" and "can't possibly know what I'm talking about." I don't do this sort of thing for a living.
I assume, by HDV, you mean 1280x720 or 960x720 (anamorphic).
First and probably foremost: ALL digital cameras add a tiny bit of softening to the images produced so as not to get "jpeg artifacts" (or moire patterning) corresponding to each "cell" (pixel) of the imaging sensor. These are discreet data collectors and that's not exactly how analog light works. The higher the cell count, the better looking the image, but the image data is still discreet and there is some algorithmic "blending" that goes on in camera when images are produced (particularly the JPEG export options... RAW might be different.) [This is a **feature** of digital imaging.]
It is my opinion that ALL video needs some sharpening — I call it cleaning. [This isn't in the list, just my opinion.]
Second would be that Final Cut already does a rather phenomenal job of upscaling video. Well sharpened HDV video will still look pretty outstanding upscaled.
Now, some sharpeners use an algorithmic computation to create artificially hardened edges giving the appearance of a sharper image. These are helpful, but only up to a limit. Go too far and you end up with something like:
(this is original appearance - 1280x720 exported from a 1920x1080 project)
To me, sharpening is a two step approach:
1) "cleaning" the original video which is adding just a "touch" of algorithmic sharpening (removing the "fog")
2) improving the overall color contrast of the image (which creates a "softer" sharpening by improving the distinction between colors.
There is only so much you can "recover". Make the most of what you get.
Here's another example - a 720x480 frame upscaled to 1080HD:
original:
"treated":
A lot of "sharpening" is simply improving the visual details in the image. (Even if you have to live with the "jaggies" in the bamboo leaf stems"). [Care must be taken not to blow out the highlights!]
It's a bit of an art form — and subjective. I learned the techniques from old Photoshop techniques from before the days the app did *everything* for you.
I can tell you I used effects that I created, but I can't you anything more (against forum protocols — they're "commercial"). The effects I made are **fine tuned** to my preferences. Otherwise, they are not really anything "special" — made in Motion with off the shelf filters. I tend to use a combination of effects in Final Cut: a cleaner and a custom color balance effect*. I would say that they took about 10 years to develop to their current level of "refinement". [More truthfully: I've had to dumb down a bunch of more generalized effects I've created because nobody remembers how to apply the old "photoshop techniques" anymore — I've had to repurpose them for more specific functions.]
*I tend to create very small, purpose-focused effects instead of effects with a mile long parameter inspector that try to do everything. Just "add-what-you-need" effects.
As an aside: I've never seen two clips able to use the exact same settings. A "one application fits all" is not likely unless you can be satisfied with a minimum level of sharpening.
