7:10 I think your conclusions are basically correct; for the final output (either 96ppi for screen or 270ppi for inkjet), one is very hard-pressed to see defects at reasonable levels of compression. I strained, and knew exactly what to look for in the side-by-side images. For archiving of images which will have subsequent processing, non-lossy storage is the best. Enlarging brings out the difficulties most clearly. So does rotation. Even curves. Even cropping! [The 16X16 computation shifts. We have a thread about this somewhere.]