If you source high quality photos, then work in an HD frame size. 1920 X 1080 should look MUCH better than what you've been doing. You're up converting SD to HD. Should be simply working in HD from the get go.
8-Core 3.0 Intel Mac Pro, Dual 2 gig G5, AJA Kona SD, AJA Kona 2, Huge Systems Array UL3D, AJA Io HD, 17" MBP, Matrox MXO2 with MAX - Cinema Displays I have a 22" that I paid 4k for still working. G4 with Kona SD card, and SCSI card.