A method includes, using at least one processing device, obtaining an image of a web of creped tissue paper and identifying a caliper measurement of the web using the image. The caliper measurement is based on a dominant frequency of the web and a standard deviation of diffusely-reflected light from the web. The dominant frequency of the web can be based on a number of crepe folds having a dominant crepe fold size that fit within a specified unit distance of the web in the image. The dominant crepe fold size can be determined using a discrete auto-covariance function of the image or a second image of the web. The standard deviation can be based on a variation of reflected light from larger crepe structures in the web.