Basic raster modification

Hi all, my first post so go easy.

I currently have autocad 2009 with raster design 2009.

I am a reincarnated autocad user (i think r12 was the last version i used) and i am getting by. However i am trying to do basic tiff modifications using raster design which i have never used before.

Basically i want to colour part of the tiff image green (to show this as a deletion) and colour part of the image red to show additions.

How do i do this?

I have created 2 layers one green and one red. By creating a REM region i have managed to highlight the parts of the image i want to place on the green layer and move them onto this layer. The vector images i want on the red layer i have no problems with.

I now have a drawing with 3 layers

0 = existing tiff

green = parts of the tiff i want to delete

red = vector images i have added to the drawing.

Everything looks OK until i go to plot the drawing. The green tiff parts of the drawing dissappear but everything else plots fine.

Can anyone help please

i have now managed to create thr green part of my drawing with the following method

1 - Create a new green layer

2 - Create a REM of the objects i want green and put them on green layer.

3 - Convert the REM back to the raster image.

I now have a raster which is part green and the rest black.

When i plot this drg everything is fine but if i close autocad down and reopen the drg the preview looks fine but when the drawing opens the green parts have changed back to black.

How do i keep the green parts green when i reopen the drawing?