Recommendations to others considering ImageJ:
It's the best software for image analysis I have ever come across. Most of your requirements will get fulfilled with this. You might need to play around a bit. One could also connect it with Matlab and go for other sophisticated functions. Review collected by and hosted on G2.com.
What problems is ImageJ solving and how is that benefiting you?
Being a cell biologist, my work deals with high-end microscopy and subsequently analyzing the images obtained. ImageJ reads most of the commonly used image files. I have been using ImageJ for 6 years to process images, do segmentation of cells, thresholding images and automate analyze particles, track moving objects (moving proteins inside cells), to name a few. One could also automate a lot of functions using the macro, which can also be used to do batch processing of images. Review collected by and hosted on G2.com.