I'm using PrPro CS 5.5 with a supported video card for GPU acceleration. I've been testing various export settings to go from 720p60 to SD DVD. I've tried going straight from the HD timeline to AME, I've also tried putting the 720p video in a SD timeline, scaling it (about 65%, I recall), and exporting. Both look pretty good, but both also look soft.

I also do a lot of still photography and Photoshop work, and when I downsize still images I sometimes add a little sharpening to 'crisp up' the image.

I tried it on my video test and it does seem to help a bit, with the expense of more noticeable noise and grain. I'm going to test some more to reduce the effect of the noise, but I thought I'd ask if others included some light sharpening in their HD -> SD workflow?

Maybe I'm going down the wrong alley looking for how to improve the SD output? I figure that the softness has something to do with the interlaced aspect of the DVD format, and maybe sharpening is not the right method?

The basic problem for me is that being used to working with, and looking at, high definition imgages as the routine, SD images, even at their best, just don't look up to speed by comparison.
The workflow that I have evolved for testing that my Hi Def to DVD transcoding and tweaking is the best it can be, is to render a sample of my project out to DVD, burn a disk, and play it on an "upscaling" DVD player with HDMI out to an HDTV. If the original footage was well shot, and the postproduction work flow optimal, the HDTV imagery should look quite satisfactory and "nearly HD". Or, what you see on the HDTV may provide very accurate clues for further tweaking- not only sharpening, but possibly gamma adjustment, color saturation, etc.
For me, this is the acid test, and I think it provides more useful info to me than what I see on the NLE monotor.

One thing you will notice with Photoshop and reducing image sizes is the Bicubic interpolation which sharpens the image. Starting with CS5, the MRQ function when used with CUDA uses the same Bicubic interpolation as Photoshop when scaling down. This is a great feature than no other NLE has, which is why people recommended applying a slight blur when going from HD to SD. But we don't have to do that with Adobe.

It's a good point you raise David. We probably all shoot in HD and only downscale when we come to make the final DVD and after looking at all that hi-def for so long SD can look very disappointing.

I agree with the others here that sharpening does add to the noise - so if you've shot at a hi-gain setting it ends up looking a lot grainier. I'm very familiar with Photoshop's 'unsharp mask' and it sounds like Steve is saying CS5 uses the same (highly effective) sharpening algorithm. I'm pretty sure my Edius 6 simply does a crude overall sharpening, but even so I do add it to my SD output.

I know all about BD players upscaling the DVD into a 1080 TV but I'm pretty sure (from client's take-up of Blu-ray) that few of them have this. So I sharpen and be damned. If it looks better then it is better.

tom.