//davor
      for ( i = _base.Count - 1; i >= 0; i-- ) {
        //...
        for ( y = Math.Max( 0, Area.y ); y < Area.y + Area.height; y++ ) {
          off_y = y - Area.y;
          ptr = baseptr + y * _line + area_x * 4;
          for ( x = area_x; x < Area.x + Area.width; x++ ) {
            off_x = x - Area.x;
            if ( ptr[3] != 0xFF ) {
              if ( _base[i].pixels[off_x, off_y].a == 1.0f ) {
                ptr[0] = ( byte )( _base[i].pixels[off_x, off_y].b * 255 );
                ptr[1] = ( byte )( _base[i].pixels[off_x, off_y].g * 255 );
                ptr[2] = ( byte )( _base[i].pixels[off_x, off_y].r * 255 );
                ptr[3] = ( byte )( _base[i].pixels[off_x, off_y].a * 255 );
              } else if ( _base[i].pixels[off_x, off_y].a != 0.0f ) {
                alphaf = _base[i].pixels[off_x, off_y].a;
                alpha = ( byte )( alphaf * 255 );
                ptr[3] = alpha > ptr[3] ? alpha : ptr[3];
                ptr[2] = ( byte )( ptr[2] + alphaf * ( ( byte )( _base[i].pixels[off_x, off_y].r * 255 ) - ptr[2] ) );
                ptr[1] = ( byte )( ptr[1] + alphaf * ( ( byte )( _base[i].pixels[off_x, off_y].g * 255 ) - ptr[1] ) );
                ptr[0] = ( byte )( ptr[0] + alphaf * ( ( byte )( _base[i].pixels[off_x, off_y].b * 255 ) - ptr[0] ) );
              }
            }
            ptr += 4;
          }
        }
      }

//danach
      for ( i = _base.Count - 1; i >= 0; i-- ) {
        //...
        for ( y = Math.Max( 0, Area.y ); y < Area.y + Area.height; y++ ) {
          off_y = y - Area.y;
          ptr = baseptr + y * _line + area_x * 4;
          for ( x = area_x; x < Area.x + Area.width; x++ ) {
            off_x = x - Area.x;
            if ( ptr[3] != 0xFF ) {
              alphaf = _base[i].pixels[off_x, off_y].a;
              if ( alphaf == 1.0f ) {
                ptr[0] = ( byte )( _base[i].pixels[off_x, off_y].b * 255 );
                ptr[1] = ( byte )( _base[i].pixels[off_x, off_y].g * 255 );
                ptr[2] = ( byte )( _base[i].pixels[off_x, off_y].r * 255 );
                ptr[3] = ( byte )( alphaf * 255 );
              } else if ( alphaf != 0.0f ) {
                alpha = ( byte )( alphaf * 255 );
                ptr[3] = alpha > ptr[3] ? alpha : ptr[3];
                ptr[2] = ( byte )( ptr[2] + alphaf * ( ( byte )( _base[i].pixels[off_x, off_y].r * 255 ) - ptr[2] ) );
                ptr[1] = ( byte )( ptr[1] + alphaf * ( ( byte )( _base[i].pixels[off_x, off_y].g * 255 ) - ptr[1] ) );
                ptr[0] = ( byte )( ptr[0] + alphaf * ( ( byte )( _base[i].pixels[off_x, off_y].b * 255 ) - ptr[0] ) );
              }
            }
            ptr += 4;
          }
        }
      }