The following matrix was derived from imagesc(rand(10,10)) as a pure example. 
I was wondering if there was a way in MATLAB to give a bold black border to certain elements? I did a poor example in MS paint just to get the point across. 
我认为更好的替代方法是使用patch， 例如：
imagesc(rand(10,10)), hold on
vert = 0.5+[0 0; 1 0; 1 1; 0 1]; % x and y vertex coordinates
fac = [1 2 3 4]; % vertices to connect to make square
patch('Faces',fac,'Vertices',vert,'FaceColor','none','LineWidth',2)
vert2 = 0.5+[5 6; 5 8; 9 8; 9 5; 7 5; 7 6]; % x and y vertex coordinates
fac2 = [1 2 3 4 5 6 ]; % vertices to connect to make the other closed polygon
patch('Faces',fac2,'Vertices',vert2,'FaceColor','none','LineWidth',2)
请注意，我向顶点坐标添加 0.5 的原因是因为imagescbin 以整数值为中心，因此 bin 边缘位于 0.5 值上。