Canvas - Get position of colour if available

Canvas - Get position of colour if available

Is it possible to get the position of a colour on canvas.
I know you can get the colour at a position like this
context.getImageData( arguments ).data
But I would like to try and find a colour in canvas, so say I would have
this colour black.
rgb(0, 0, 0);
I would like to get the position of that colour if it exists on canvas,
I've asked Google but I only get the Get colour at position which is the
opposite of what I need.