Alternative methodologies for characterizing aggregates at non-binary fields of view.

Panel A: Sample simulated field of view, corresponding ground truth and parameters used in the 10 sets generated. Panel B: Upper—First-derivative of the granulometric profile of the sample field of view shown in Panel A. It can be seen that there are four major troughs at radii 2, 5, 7 and 9 approximately corresponding to the ground truth radii of the aggregates. Lower—Extracting aggregates with a radius of 8 pixels, by subtracting the opened image at a radius of 9 from that opened at a radius of 8. Further thresholding and processing may be performed (described in Panel C). Panel C: Demonstrating the effect of SBR on the accuracy and specificity of segmentation of aggregates. The blue crosses represent the TET and TEE values of individual simulated fields of view (see text for a description of how TET and TEE are calculated), while the means of Sets 1 through 10 are represented by different shades of red, from darker to lighter respectively. Upper—As SBR increases, TET increases. Notice the low TET values obtained for the Sets 1–3, especially at low SNR. Lower—The result of applying the same segmentation pipeline not to the original image but to aggregates of a single radius (8 pixels) obtained using granulometric analysis (as in Panel B). The TEE values are generally lower than those of the pipeline in the upper panel. However, this method offers better results at low SBR’s (Sets 1–3).