Blocks scanning is proposed based on the thoughts of the scanning technique and the vector technique.The block-square is determined based on the defocus and the distance between the stars.In every block

the pixel with highest grayvalue is found and the position is stored.The stored pixels will be eliminated if the surrounded pixels have higher grayvalue or the number of the pixels with grayvalue higher than the grayvalue threshold is lower than the number threshold.The left is the center of the stars in the image.Simulation result proves the validity of the method.