Imagesc - insert grid lines

Hello,

m = 21 x 21 matrix

I want to draw grid lines onto the imagesc figure to signify certain groupings. And I don't want to do this manually since I have ~20 of these.

eg. black box around [1:3,1:3] to indicate that 1:3 is one group. red box around [5:10,5:10]

Answer 1

[Wayne King]

imagesc(randn(21,21));
hold on;
h1 = rectangle('position',[1 1 3 3]);
set(h1,'EdgeColor',[0 0 0],'linewidth',3);
h2 = rectangle('position',[5 5 10 10]);
set(h2,'EdgeColor',[1 0 0],'linewidth',3);

[Image Analyst]

Oh, is that what she wanted? Just simply displaying lines going from pixel center to pixel center? That's easy. I thought she wanted to go *around* the pixels, like right along the edges of the pixels, not through the centers, like Steve Eddins did on his recent blog entry.