The invention discloses an adaptive 
particle swarm algorithm-based 
grayscale threshold obtaining method and an 
image segmentation method, and belongs to the technical field of 
image processing. The 
grayscale threshold obtaining method is characterized by comprising the following steps of S01, performing 
population initialization on a 
grayscale value of an image; S02, calculating a fitness value of an individual in a 
population; S03, calculating an optimal position and a 
global optimal position of the individual in the 
population; S04, updating the optimal position and the 
global optimal position of the individual in the population; and S05, judging whether a stop condition is met or not, and if the stop condition is met, obtaining an optimal solution and obtaining an optimal grayscale threshold, otherwise, executing the step S02 to enter a next-generation population, wherein the optimal position and the 
global optimal position of the individual are dynamically adjusted by adopting an inertial weight in the step S04. The grayscale threshold obtaining method has autonomic learning property, adaptivity and relatively high robustness, can concurrently solve the grayscale threshold globally and better avoid 
local optimum, and is accurate and efficient.