Introduction[edit | edit source]

ImageJ is a Java-based program used for image processing and analysis. It can be used to determine packing factors (or void fraction) of nanocolumnar structures if top-down SEM images are available.

Protocol[edit | edit source]

  • Open the top-down SEM image of the layer in ImageJ.
  • Select Image - Type - 8-bit
  • Thresholding: Select on Image - Adjust - Threshold
  • Set dark background and ajust colours/threshold as appropriate - Click Apply once set (try to colour the tops of the columns, do not overestimate at this stage and compare with original picture)
  • Select Process - Binary - Make Binary
  • Closing: Select Process - Binary - Close
  • Filling: Select Process - Binary - Fill Holes
  • Watershed Maxima: Select Process - Binary - Watershed
  • Particle Analysis: Select Analysis - Analyze Particles
  • Recommended Settings: Size (10-infinity), Circularity 0.5-1 (only near circular shapes included), Display results, Summarize, Exclude on Edges