Removing colour cast

[MrBuk]

I have a Cokin 0.9 ND filter and it seems to leave a magenta colour cast on the photograph.

Can some on advise on how best to remove the colour cast? I have CS4.

The filter is a Cokin P series and I am thinking of replacing some of the filters any advice on a make that will fit the Cokin holder?

[Oly Paul]

If you shooting raw then best remove it using the white balence in the raw converter, if jpeg then you will have to resort to the colour balence tool ( Image> Adjutments > Color Balence), try slightly moving the magenter slider towards green. you could also try using Auto color in the same location, it sometimes gives good results.

Theres also curves for the experianced, but from the nature of the question I'll leave that for another day.