bad v4l2 colors in linux 2.6

[csj <csj@zapo.net>]

I have a Bt878-based TV tuner card (WinFast something) that's
producing satisfactory video in linux 2.4.  Under 2.6 the video
is under-saturated (i.e. the colors look pale).  What am I
missing?  Are there any magic options to pass to the v4l2 (linux
2.6) drivers to get my "rich" v4l (linux 2.4) colors back?

I'm using a variety of tv apps, including xawtv, tvtime and
mplayer, with similar results: rich, saturated colors in linux
2.4 but pale, undersaturated colors in 2.6.