
Notice the ghosting on the left side of the mountains here:
http://i40.photobucket.com/albums/e236/ ... 1378162371
Can't be seen here around the cloud:
http://i40.photobucket.com/albums/e236/ ... 1378162362
Pretty bad next to the bright letters here:
http://i40.photobucket.com/albums/e236/ ... 1378162348
And here is the same shot from the Sega Saturn version on Sonic Jam. It looks the same, but really the ghosting is noticeably better on the Saturn:
http://i40.photobucket.com/albums/e236/ ... 1378162351
So since this also show on the Saturn (and any other console) and the fact that it only shows in red and blue colors I'm guessing that it's caused by the color subsampling to YUV422?
I completely forgot that all systems showed ghosting like this because the scanlines hide it quite well. The Mega Drive is probably a bit worse in blue colors because it's not completely rid of the interference from the clock signal. Just my guess of course
