Particle analysis

A potentially useful task in many imaging fields, especially in microscopy, is the automatic detection and measurement of the particles present in a given image. Consider the following one, taken from the original set of tuberculosis images that we have presented previously (tuberculosis_full.tif):

Note that the zoom level has been reduced to show the whole image on the page. If you open that image on ImageJ, you can see that there are many small green objects: those are the Mycobacterium tuberculosis bacilli, and we want to count them. How many of them are there in the image? One way of accomplishing that task is to count them manually. That can be hard even for a single image, and think about having to count hundreds of them. So, let's see if we can get ImageJ to do the job for us.

In the first place, note that this is an RGB color image. When we run the cursor over the image, a triplet of values is shown on the status bar on the main window (one for each Red, Green, and...