The invention discloses a 
gangue identification sorting method based on 
gangue-free image filtering and 
BLOB analysis. The method comprises the following steps of performing 
image acquisition on 
coal,calculating image three-moment evaluation on a received image by an industrial 
personal computer through 
computer software to obtain a three-moment evaluation value of the image, comparing the three-moment evaluation value of the image with a set initial threshold value, performing 
BLOB analysis on the image, and obtaining coordinates of a point at the upper left corner of the maximum partition and the width and height of distribution; performing three-moment 
local evaluation on the area range where the partition is positioned, judging whether the current 
gangue is marked gangue which sends an instruction or not, if yes, not performing 
processing, and if not, sending a gangue sorting instruction; and picking gangue through a 
robot. According to the method, full-
image analysis can be transited to accurate analysis and judgment of a local attention area, interference of background and stray objects on recognition is reduced, gangue is effectively recognized, and then popularization andapplication are facilitated.