The invention discloses a method for detecting cracks in a bridge image. Due to the fact that manual marking has certain subjectivity, detection precision depends on experience knowledge of experts, and experience lacks objectivity in quantitative analysis. The method comprises the following steps: 1, detecting the position of a crack in a bridge floor image, and completely extracting the morphological characteristics of the crack; 2, extracting real parameters of cracks in the image. According to the invention, an
image processing technology is used to replace human eyes to complete automaticnondestructive detection of bridge cracks. Aiming at the unique spatial
ductility and gray distinguishability of bridge cracks, the improved median filtering
algorithm is provided, according to the characteristics of crack edge similar gray
linear distribution, on the basis of original median filtering, the thought of the similar gray scale extension direction is introduced, interference of bridge floor image composite
noise can be restrained more effectively, the
signal-to-
noise ratio of the image is increased, the continuity of detail information of the crack edge is kept, and the reliability of fidelity filtering of a target crack is improved.