someone on neogaf made a good comparision of the versions
No paper filter and bloom (emulated PCSX2 version):The paper filter is a post-processing effect (along with the bloom effect) that the original PS2 version had. Unfortunately, this effect was not carried into either the Wii version, nor the PC emulated PS2 version (due to PCSX2's disabling the effects because of bugs).
Let me give you an example:
No paper filter and bloom (emulated Dolphin/Wii version):
Paper filter and bloom (PS2 version):
Paper filter and bloom (HD remaster):
as you can see, HD has restored the game to former glory that the Wii took away