Extended Data Fig. 7. Process for analysing the size distribution of the L1₂ particles by batch image-processing protocol.

First, an edge detection algorithm was applied to the raw images to isolate particles from the matrix. Second, a contour detection algorithm was used to search for closed contours. Third, the particle shape was approximately evaluated and converted into a square shape. Finally, the size distribution of closed contours (particles) was computed. The algorithm was constructed using a Python⁶². For each sample, the particle size distribution was derived from more than 20 ECC images of different sample regions.