Figure 4. Gumbel plots of estimated cumulative probability function versus largest difference between adjacent CT values for data on images of polymer tubes I and IV inFigure 1a, as reconstructed by reconstruction kernels FC01, FC50 and FC52. White circles represent data on polymer tube I, reconstructed by the FC52 reconstruction kernel; black circles on polymer tube IV reconstructed by FC52; white squares on polymer tube I reconstructed by FC50; black squares on polymer tube IV reconstructed by FC50; white triangles on polymer tube I reconstructed by FC01; and black triangles on polymer tube IV reconstructed by FC01.