HOW TO draw bitmap on a form but just on a desired color parts

I need to draw a bitmap over complete form but bitmap must be visible
only where particular color exists: for example, I have form with
several controls on it (labels, buttons and panels) and some panels
are colored red - I want to have bitmap on a form that will be seen
only in red panels (red panels will look like a 'window' through form
becuasse part of bitmap will be visible throutgh them)

Is this possible to made and to work fast ?
I use DELPHI 3  ...
Arminio.Gr...@USA.Net                     Pozega, Croatia