Click on the Region of Interest (ROI) button. Click and drag the mouse whilst holding down the left mouse button. This will create a region of interest. The size of the ROI will be displayed in the status bar as it is drawn. To see the size again, click on the ROI button. To move the ROI click on the ROI and drag while holding down the left mouse button. To calculate the number of capillaries and length of capillaries within the ROI press the button. This will open the Image Results window. Add more counts or lines to the image, or move or create a new ROI. Press the calculate button again. The new results will be added to the Image Results window. Click on the Show grid button to display the grid. Press it again to remove the grid. The grid size can be adjusted using the Settings | Grid menu option. Click the origin button. Now click the left mouse button on the image. The grid will now be aligned with the new origin, and the start positions in the dimension list will now be relative to the new origin. Double click the right mouse button on the image. This now will reset the position of the target crosshair.