Get pixels of shapes in Fabric JS (triangle, circle, path)

Question

Im calculating temperatures from parts of image, with Fabric JS and Ojects. When i get the pixels from object, Fabric give mi pixels of BOUNDED square and not from SHAPES.

How i get only pixels from shapes, or "target.containsPoint(point)" that not see the gosth pixels... Image 1 Image 2

https://jsfiddle.net/kixupere/atn0e4j6/

    xx = ~~event.target.left; // pasar a entero
    yy = ~~event.target.top; // pasar a entero
    height = event.target.height * event.target.zoomY; // altura inicial x escala
    width = event.target.width * event.target.zoomX; // anchura inicial x escala
    zoomY = event.target.zoomY; //  escala
    zoomX = event.target.zoomX; //  escala

    var recuento=0;
    var index=0;
    var puntos = new Array();
    var puntos_x = new Array();
    var puntos_y = new Array();
    var point = new fabric.Point();
    var point_anterior = new fabric.Point();
    var point_actual = new fabric.Point();
    point_anterior.setXY(0, 0);
    point_actual.setXY(0, 0);

        for(j=yy; j <= (yy + height) ;j++){
            for(i=xx; i <= (xx + width) ;i++){
                point.setXY(i, j);  
                if(event.target.containsPoint(point)){
                    if(i < xx+3 || j < yy+3){ //+3 y +3
                        xxxx=parseInt(point.x/3);
                        yyyy=parseInt(point.y/3);
                        point_actual.setXY(xxxx, yyyy);
                        if(point_anterior.eq(point_actual)){
                        }else{
                            puntos_x[index] = xxxx;
                            puntos_y[index] = yyyy;
                            index++;
                            recuento++;
                            point_anterior.setXY(point_actual.x, point_actual.y);
                            
                        }
                    }
                }else{
                }
            }
        }

Thanks