Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Blob extraction is an image segmentation technique that categorizes the pixels in an image as belonging to one of many discrete regions. Blob extraction is generally performed on the resulting binary image from a thresholding step. Blobs may be counted, filtered, and tracked. Inconsistent terminology for this procedure exists, including region labeling, connected-component labeling, blob discovery, or region extraction. Well-known algorithms for accomplishing this exist, including a sequential algorithm and recursive algorithm. Blob extraction is related to but distinct from blob detection.