Fig. 2

Linear isotropic diffusion process. a shows a black ball test image with white background. The features present in the image are isotropic in shape with a constant radius of two pixels. b shows the smooth spatial entropy graph resulting from diffusion process on natural scale parameter. The entropy change with natural scale change is displayed in (c), where the peak corresponds to the size of the black balls. The diffused image resulting from stopping the diffusion process at the location of the peak in entropy change is shown in (d). The diffused image is converted to binary image using Otsu optimal threshold of 0.63. The final binary image is displayed as (e)