Why in seasons 1-4 of smallville is the picture quality lesser on some episodes?
The first four seasons were shot in standard definition; production was upgraded to high definition starting with Season 5. What you describe is an occasional side effect of upconverting standard definition video to HD. I think the blurriness you described is from standards converted European prints of certain episodes that got remastered back into the US broadcast standard (the same situation happened when Warner Bros. released the later seasons of Dallas when UK prints were used for some episodes).
