A driving design criteria of both NIH Image and ImageJ was to keep the program simple with no complex user interfaces. Upon opening ImageJ, just a single toolbar appears, and it is from this straightforward interface that all of the capabilities of ImageJ can be found and used. The ImageJ toolbar has stayed basically the same for 15 years similar to how NIH Image largely remained the same (Figure 1). Rasband wanted a stable program interface that wouldn’t change on users, but he also needed a way to add new functionality based on the needs of his user community. This philosophy of limiting complexity also drove how he decided what functionality to integrate into the program directly or distribute as plugins.
