Just been reading through the older posts again and came across this post from Laserman:

Laserman said:

Thanks for the PM Moth3r.
By that I meant the best way to fix the problem is to do it electronically rather than trying to filter it later.
Basically the problem with Laserdisc is that even the best players crap out at around 5 to 5.5MHz. This leaves laserdisc with a relatively slow rise time (the time taken for a signal on the video path to change from one colour to another) and can cause the 'ringing' or halos as well as awful transitions between colours.
To solve the problem somewhat you can map the Chroma signal to the Luma signal. The Luma signal is relatively quick, around 150nanoseconds, whereas the chroma signal lags with a rise time of around 800nanoseconds. By devising a circuit to lock the chroma signal rise time to the Luma's faster rise time the effect can be pretty much eliminated, resulting in a DVD like picture from laserdisc.

If you have a laserdisc with a set of colourbars on it you can see the problem between the Magenta and Green vertical bars quite clearly.
If you were smarter than me you could then work out a way to lower the rise time of the Luma signal with some sort of rise time acceleration and nail the halos forever.

Now, this sounds really interesting. Can anyone shed any further light on this whole 'remapping' business and how it might be achieved please?