Rect max;
    for(unsigned l1=0; l1<LINES; ++l1) {
        for(unsigned l2=l1; l2<LINES; ++l2) {
            for(unsigned c1=0; c1<COLS; ++c1) {
                for(unsigned c2=c1; c2<COLS; ++c2) {
                    bool rect_noir = true;
                    for(unsigned l=l1; rect_noir && l<=l2; ++l) {
                        for(unsigned c=c1; rect_noir && c<=c2; ++c) {
                            if(im({c,l}) == od::Color::White) {
                                rect_noir = false;
                            }
                        }
                    }
                    if(rect_noir) {
                        unsigned hei = l2 - l1 + 1;
                        unsigned wid = c2 - c1 + 1;
                        unsigned area = wid * hei;

                        if(max.area < area) {
                            max.pos.x = c1;
                            max.pos.y = l1;
                            max.size.wid = wid;
                            max.size.hei = hei;
                            max.area = area;
                        }
                    }
                }
            }
        }
    }