Interface And Graphics :: Algorithm To Find Identical Adjacent Pixels In Bitmap?

I need to write a code to find identical adjacent pixels in a bitmap image. It should work as the 'magical wand' in Photoshop.My images are always black and white (white background with car parts drawed in black). Given the x,y coordinate for a single black pixel in the whole image, the code should find (and paint with another color, say red) all other black pixels that are linked to that one, and so on, until all linked black points will be painted in red.This way, suppose that I have an image with 4 car parts drawed, then if I give the x,y coordinate of a black pixel, just THAT part to whose the black pixel belongs to should be painted in red. All other parts will remain black. Does it make sense?At the end, there are two pictures (before and after) to help understanding what I need to do to the images.I tried a simple 8-pixel adjacent approach for every pixel (starting on initial coordinate) but it turns out into a very stupid and endless looping algorhitm.

Code:
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Windows.Forms

[code]....