How are you delivering?
There was a post on this site a couple of years ago by Jeff Belune (as I recall) that provided a work flow for this. I fiound it to be effective. Most of the people who post here recommend that you do the scaling in Photoshop and then import the *.PSD file. The pixel dimensions W x H must match the scenario preset pixel dimensions (the DPI and/or image dimensions in inches, have no meaning). If your scenario is 1920 x 1080, then that's what the image size needs to be.
I only remember some of the steps Jeff laid out, but, it was to open the image in Photoshop, set the GENERAL preference to best for reduction, Change the image to 16 bit. Make color, exposure changes as desired, use unsharp mask set to 198, 0.6, 2, set the crop tool to your desired pixel dimensions, and crop the image to the desired size, if desired change the mode back to 8 bit, and save the file under a new name (never mess with your original. I created a photoshop action to speed the process.
Thanks for the specific info. I took a class in Premiere and we didn't do anything to the photos and they looked fine. I'll try your method.