Following a message in Discourse (it have been deleted shortly after...), I
tested imageMode(CENTER) inside a PGraphics in P2D mode.
It appears the same operation is done twice.
PGraphics.image(PImage image, float x, float y) (and the version with all
parameters)
is offsetting the coordinates by half the image size, then call imageImpl.
PGraphicsJava2D.imageImpl() just calls g2.drawImage() and result is OK.
PGraphics2D..imageImpl() calls simple_image() which does:

if (imageMode == CENTER) {
sx1 -= image.width / 2;
sy1 -= image.height / 2;
}

Double offset...

Demonstration code:

PImage niceImage;
PImage smallImage;

void setup()
{
size(800, 800);
smooth();
noLoop();

niceImage = loadImage("Globe.png");
smallImage = loadImage("icon.png");

PGraphics pj = createGraphics(600, 600, P2D); // Change to JAVA2D for
correct result
pj.beginDraw();
pj.image(niceImage, 0, 0);

pj.imageMode(CENTER);
pj.image(smallImage, pj.width/2, pj.height/2);

pj.line(0, 0, pj.width, pj.height);
pj.line(0, pj.height, pj.width, 0);
pj.endDraw();

image(pj, 100, 100);
}

Processing 1.0.1, Windows XP Pro SP3

Thanks.. did the original poster delete the message? Or is there something
wrong with the board?

(In reply to comment #1)
> Thanks.. did the original poster delete the message? Or is there
something
> wrong with the board?

No idea. Just got an error when sending the answer, it was no longer in the
sub-forum listing...
Perhaps OP saw it works in JAVA2D and thought post was no longer relevant.

thanks, now fixed for 1.0.4.