Assessing Changes in Texture Periodicity Due to Appearance Loss in Carpets: Gray Level Co-occurrence Analysis

Texture may be defined with respect to the global properties of an image or to the repeating units that compose it. We have attempted to isolate the periodic components of texture in wool carpets for the purpose of assessing the effects of wear on carpet textures. Texture is defined as any recurring spatial pattern of sampled gray level intensities. We restrict attention to textural features that reflect the physical charac teristics of the carpet tuft assemblies. Our test materials consist of four kinds of double ply wool carpets of differing textures divided into control, light, and heavy wear samples. Video images were recorded under several magnifications using a Truevision Vista board. Image files with 256 gray levels were converted to 32 levels using histogram equalization. Textural features were evaluated by computing gray level differences and second-order gray level statistics. We discuss results for spatial gray level depen dence (SGLDM) and gray level difference (GLDM) methods for a range of intersam pling distances. Results for our carpet series show that SGLDM and GLDM yield very similar trends, statistical trends within each method are correlated, overall, these mea sures are generally effective for differentiating the degree of wear as well as providing an indication of textural periodicity, and changes in frequency may be examined by subjecting SGLDM and GLDM statistics to spectral analysis.