# Blob Median

The median of a blob is the intersection of two lines, one parallel to the x- and the other parallel to the y-axis, such that half of the total pixel weight of the blob lies on either side of the line. Because blob median is a nongeometric property, it is a less reliable indication of a blob's true location than center of mass. However, a blob's center of mass is much more susceptible to spatial quantization errors than is blob median; blob median might be more useful than center of mass in cases where the blob is circular and where a hard binary threshold is being used to segment the image.