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1. Evaluate the function with some image as a variable.

2. Set the image size, the polygon color, and the boundary thickness.

3. Succesively pressing Alt+Click set the locators (having appearance of circles). Adjust the locators, if necessary. Adjust the colors, opacity and the boundary thickness.

4. Press the button "Pick up the stroked Area". Done.

5. Call the variable graphicsPolygon, where necessary

Here is this function:

1. Evaluate the function with some image as a variable.

2. Set the image size, the polygon color, and the boundary thickness.

3. Succesively pressing Alt+Click set the locators (having appearance of circles). Adjust the locators, if necessary. Adjust the colors, opacity and the boundary thickness.

4. Press the button "Pick up the stroked Area". Done.

5. Call the variable graphicsPolygon, where necessary

   Here is this function:

I can offer a very simple way of copying any image element as a polygon, that canafter that be used as an element of any graphics or art work done within Mathematica. It is based on the function entitled "strokeArea".

I can offer a very simple way of copying any image element as a polygon, that can after that be used as an element of any graphics or art work done within Mathematica. It is based on the function entitled "strokeArea".

Clear[strokeArea];
strokeArea[image_] :=
  Manipulate[
   DynamicModule[{pts = {}},
 
Column[{
  
   Dynamic@LocatorPane[Dynamic[pts],
    Dynamic@
     Show[{image, 
       Graphics[{color, EdgeForm[{color, Thickness[thickness]}], 
         Opacity[opacity], Polygon[pts]}]
                             }, ImageSize -> imageSize], 
    LocatorAutoCreate -> True, 
    Appearance -> 
     Graphics[{{color, Thickness[thickness], 
        Circle[{0, 0}, 0.5]}}, ImageSize -> 10]
                                          ],
  Button["Pick up the stroked Area",
   Clear[graphicsPolygon];
   graphicsPolygon = 
    Graphics[{color, EdgeForm[{color, Thickness[thickness]}], 
      Opacity[opacity], Thickness[thickness], Polygon[pts]}];
   ]
  }]
], Row[{Control[{{thickness, 0.005}, 0, 0.015}], Spacer[15], 
 Control[{color, Red}]}], Column[{
 Control[{{imageSize, 450}, 300, 600}],
 Row[{Spacer[12], Control[{{opacity, 0.5}, 0, 1}]}]
          }],
 ControlType -> {Slider, ColorSlider, VerticalSlider}, 
   ControlPlacement -> {Top, Left}, SaveDefinitions -> True];

The cursor are visivle as thin circles here, and the blue boundary is given in order to guide the eye, you may remove it.

Clear[strokeArea];

strokeArea[image_] := 

  Manipulate[
   DynamicModule[{pts = {}},
     Column[{
            Dynamic@LocatorPane[Dynamic[pts],
    Dynamic@
     Show[{image, 
       Graphics[{color, EdgeForm[{color, Thickness[thickness]}], 
         Opacity[opacity], Polygon[pts]}]
                             }, ImageSize -> imageSize], 
    LocatorAutoCreate -> True, 
    Appearance -> 
     Graphics[{{color, Thickness[thickness], 
        Circle[{0, 0}, 0.5]}}, ImageSize -> 10]
                                          ],
  Button["Pick up the stroked Area",
   Clear[graphicsPolygon];
   graphicsPolygon = 
    Graphics[{color, EdgeForm[{color, Thickness[thickness]}], 
      Opacity[opacity], Thickness[thickness], Polygon[pts]}];
   ]
  }]
], Row[{Control[{{thickness, 0.005}, 0, 0.015}], Spacer[15], 
 Control[{color, Red}]}], Column[{
 Control[{{imageSize, 450}, 300, 600}],
 Row[{Spacer[12], Control[{{opacity, 0.5}, 0, 1}]}]
          }],
 ControlType -> {Slider, ColorSlider, VerticalSlider}, 
   ControlPlacement -> {Top, Left}, SaveDefinitions -> True];

The cursors are visible as thin circles here, and the blue boundary is given in order to guide the eye, you may remove it and change parameters. Say, after you have successfully finished to built the polygon, change the color and the opacity to that you want the arrow to have.