In order to improve the detecting efficiency of the concrete highway pavement disease

image processing technology is applied to automatically recognize cracks

and extract the disease parameters.The crack can be detected by threshold segmentation methods.According to quantity difference of the background connected regions in the linear and reticular crack image

region labeling method is adopted to calculate quantity of background connected regions to classify cracks.According to the geometric shape differences of three kinds of linear crack

the transverse

longitudinal and diagonal crack can be subdivided by projection method.And disease parameters such as length and mean width of linear crack are measured after its skeleton is extracted by thinning.The damaged area in the reticular crack image is calculated by finding its minimum enclosing rectangle.