Load solid image, then make it transparent?

[TeknomanSlade]

How's it goin' folks? Got a new question for you...

I'm working on a complex animation that deals with sprite-style
images. I've got one sprite right now that's saved as a .PNG that's
got about 800 colors in it (according to PSP's "Count colors" function).
It's made to blend in with the background, so I can't degrade it into
a transparent .GIF without it ending up looking bad, so here's my question:

I've got the image itself surrounded by a solid green area (kind of like,
if it were a .GIF, the green area would be transparent). What I'd like
to know is, is there a way to load the .PNG into a graphics space, then
paint the green area with a color that registers as blank/transparent/null
with Java, and save that resulting picture back to the original image so
I can draw it into my scene without any trouble?

I'll drive my point home with some pseudo-code here...I'm aware it looks like
crap, but...:

Image TheObject;
Image FinalObject;
Graphics workspace;

public void init() {
TheObject = getImage(getCodeBase(), "object.png");
FinalObject = createImage(TheObject.Width, TheObject.Height);
workspace = FinalObject.getGraphics();
workspace.drawImage(TheObject,0,0,this);

// Paint the green area so that it's transparent...
workspace.floodfill(0,0,color.transparent);

// Replace original image with the new transparent one...
TheObject = FinalObject;
}

public void paint(Graphics g) {
// Draw new object three times.
g.drawImage(TheObject,0,0,this);
g.drawImage(TheObject,50,50,this);
g.drawImage(TheObject,100,100,this);
}

Can this be done?