Applying image analysis to fabric quality evaluation is suggested as a substitute for human inspection of fabric surfaces. A fabric image is captured on an image scanner, and from it, the coefficient of variation and power spectra of yarn interval are calculated as indices of irregularity in the yarn arrangement. However, neither shows a significant relationship with the results of human evaluations. As another approach to the irregularity of fabric surfaces, the power spectral peak width of the intensity data is computed. The peak width, containing surface irregularity information, shows it is related to fabric quality. The study also shows that the peak width changes with the back beam height.