Open the required image in the program and adjust the contrast – try to maximize the clarity of the edges of the selected object. Zoom the drawing so that was the most clearly visible region of the desired part of the image. This will simplify the work and will not "capture" the unnecessary pieces of the image adjacent to the working object.
Click on the toolbar (where drawn in pencil) on the left side tool called "bézier Curve". Circle the object. Best of all the process will go if you will be at approximately equal intervals to set a corner point. When the desired part is encircled, do not forget to close the resulting curve. To do this, click "Close" in the panel work with the bézier curve.
Convert all the sharp corners in a smooth line (solid curve) by using the Shape tool. Edit each straight line to the required radius, straight, arc, etc. an Alternative tool call "Form" – pressing F10.
Insert the selected object in the resulting curve to highlight it. For this, the menu "Effects" select "PowerClip", from there select "Place inside container". After that, an arrow will appear, which indicate on your curve click.
If the selected object is centered in relation to the curve, open the menu "Tools" section of the "Options" and then "Tab". Here, select the "workspace" and uncheck the option "Autocentricity PowerClip". Now the selected object is cut from the overall image.