Whoitam Image Measurement is a special tool for measuring area on a map or any image. After automatic selection it shows perimeter, width, height, area of selection. Enabling “Analyze” option is accurate but, it shows sometime slightly different two result when clicking on different position in a same region. Then you have to choose the bigger one as result. Calibration is available. It has other features like clearing noise in selection automatically. You can also measure area by polygon tool.