bitmap

Hi grasshoppers!
I'm working with a nice color aerial image over a forest in Connecticut
and I would like to display it as background in my workstation using
the
command:

xsetroot -bitmap image_name

but I don't know how to transform it to the proper format either from
the
uncompressed cell grass format or from the original tiff. Anybody knows
how to do it?

Thanks,
Agus