java 2d - How to copy a region of an image enclosed by cubic curves -

i have java program works similar bezier tool in inkscape. purpose of program allow user use curves draw path around object (like head of person) , extract (copy) pixels inside enclosed curves. in attached picture, can see there 3 blue curves form enclosed area. i'd know how copy area enclosed these 3 curves?

the code use draw curves (i omit red tangent lines , red control points simplicity):

        cubiccurve1 = new cubiccurve2d.double(             p1.x, p1.y,              p1control1.x, p1control1.y,             p2control1.x, p2control1.y,             p2.x, p2.y);          cubiccurve2 = new cubiccurve2d.double(             p2.x, p2.y,              p2control2.x, p2control2.y,             p3control1.x, p3control1.y,             p3.x, p3.y);          cubiccurve3 = new cubiccurve2d.double(                 p3.x, p3.y,                  p3control2.x, p3control2.y,                 p1control1.x, p1control1.y,                 p1.x, p1.y);          g2d.setpaint(color.blue);     g2d.draw(cubiccurve1);         g2d.draw(cubiccurve2);     g2d.draw(cubiccurve3); 

here's how solved problem:

        generalpath shape = new generalpath();         shape.moveto(cubiccurve1.x1, cubiccurve1.y1);         shape.curveto(cubiccurve1.ctrlx1, cubiccurve1.ctrly1, cubiccurve1.ctrlx2, cubiccurve1.ctrly2, cubiccurve1.x2, cubiccurve1.y2);         shape.curveto(cubiccurve2.ctrlx1, cubiccurve2.ctrly1, cubiccurve2.ctrlx2, cubiccurve2.ctrly2, cubiccurve2.x2, cubiccurve2.y2);         shape.curveto(cubiccurve3.ctrlx1, cubiccurve3.ctrly1, cubiccurve3.ctrlx2, cubiccurve3.ctrly2, cubiccurve1.x1, cubiccurve1.y1);         g2d.draw(shape);         g2d.setclip(shape);          // draw image          g2d.drawimage(image, 0, 0, this);