Method for detecting quantity and positions of cracks on surface of material

A method for detecting quantity and positions of cracks on surface of a material relates to material nondestructive inspection. The method comprises the steps of pasting a film for detecting the quantity and the positions of the cracks on the surface of the material on the surface of a tested material; continuously shooting the film for detecting the quantity and the positions of the cracks on the surface of the material of surface of the tested material by using a video camera and obtaining a surface color changing image of the film for detecting the quantity and the positions of the cracks on the surface of the material; transferring photos shot by the video camera to a computer, and recognizing the surface dark color and light color region distribution of the film for detecting the quantity and the positions of the cracks on the surface of the material by the computer; obtaining surface image light color point coordinates of the film for detecting the quantity and the positions of the cracks on the surface of the material by utilizing the computer, and finally corresponding to the quantity and the positions of the cracks on the surface of the material. The film for detecting the quantity and the positions of the cracks on the surface of the material is provided with rectangular air bags which are in arrayed distribution, are made of colorless and transparent materials and are filled with non-toxic colored gas.