ImageJ to calculate packing factors:QAS

This page was developed by the Queen's University Applied Sustainability Research Group.

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.

• 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