Using TV command instead of contour

[Amit]

Dear Friends,

I have a data in form of flags, for example, dust=1,smoke=2 and so on.
There cannot be numbers in between.

The data is in the form of 2-dimensional array, with each cell
corresponding to a latitude, longitude pair. I want to display it --
the output would look something like a chess board. If I use the
CONTOUR command, it interpolates at the boundaries, producing
incorrect plots.
This problem is solved if I use TVIMAGE program. However, I cannot
pass the latitude,longitude data to the command (like CONTOUR). Can
anyone suggest me how to use TVIMAGE or TV in a way similar to
CONTOUR?

Thanks for your help
Amit