Open your picture, transform it to 32-bits format and draw the area you want to analyze. Go to "Analize" and measue it. Then a window with the area and the average of intensity will appear. You can measure the number of pancreatic islet fibrosis you consider, everytime you click "Analyze" after drawing the area it will be recorded as a new measurement. so you can count the number of samples you have measured for the stats
Thanks for your answer but I am not sure that this will work. I have fibrosis all over the islet, which is very difficult to delimitate the affected area.