Abstract: In response to the existing challenge of full-angle bolt loosening detection based on anti-loosening lines segmentation, a method based on color segmentation and directional vector operations is developed. Firstly, the anti-loosening line image is segmented using a method based on the nonlinear stretching of the 'a' component under Lab and RGB color space conversion, and the optimal threshold segmentation of the 'R' component. Secondly, morphological operations are performed on the image using an opening operation. Thirdly, the direction vector of the minimum external rectangle of the anti-loosening line connected domain is determined through an angle-progressive minimum enclosing method. Then, the full-angle of bolt loosening is solved based on the four-quadrant inverse tangent function and certain adjustments. Finally, an experimental scheme is designed to verify the feasibility and accuracy of the algorithm proposed in this paper. Experimental results show that the detection algorithm can realize 0 to 360 degree bolt loosening angle detection, with a maximum relative error of 1.43%. The accuracy of the method is satisfactory for engineering practice, demonstrating promising application prospects.