Whites look Grey

I have noticed this in the past but in this project in particular there is a lot
of white in the background. When i export it to a Mov file using Sorenson codec
the final result is a grey bakcground instead of the crisp white. If i use
different compressors like mov with png it looks perfect. If i use mov and photo
jpg it looks grey.

the movie is 1024x768 so i can not use the mpg2 option to try that.

Any ideas?

Ok, so when i tried the MPG2 option again it actually let me increase the size
beyond 720. and this too is nice and white.

My client has a preference for MOV. why are some grey and some not. I assume it
is a restriction in color space but how do i know which and why would sorenson
have that issue.