Here are some frames from the NTSC and PAL DVDs, and the Blu-Ray: http://imgur.com/a/nymHs
Notes:
- All were taken using VLC's built-in snapshot functionality for the best quality, with no deinterlacing, aspect correction, or any other video effects or postprocessing (except see #2, below). If you know of a better way, let me know.
- The Blu-Ray images were automatically converted by imgur from .png to .jpg. The remaining images, all .png, appear unchanged from what I uploaded, based on the file size.
- The PAL images show very noticeable lossy compression. I took them from the Region 2 Limited Edition DVD box set of season 1, ISBN 5030305891015, released in 2002. There's a more recent R2 DVD edition, maybe the quality is higher.
- The DVDs are ASIN B002GP7ZWI, released in 2009.
- The Blu-Rays are ASIN B00E688720, released in 2013.
- The NTSC DVDs show evidence of 3:2 pulldown. I chose frames without noticeable interlacing for this test.
- It's possible that the NTSC video was created directly from the PAL masters, in which case this experiment won't reveal any additional detail.