Detect contours, modify ROI

Optionally, to calculate histogram click and 'Histogram icon' at 'List of images' widget.

To extract / detect contours - adjust level and window.

Open 'List of ROIs' widget - click at 'circle' icon in lower right corner.

Select ROI or create new one. To create new ROI right-click inside widget to open menu.

To draw click 'Plus on circle' icon at 2D view toolbar.

Another panel will appear.