monotone colored matrix with gridlines

I want to create a monotone image of a matrix with gridlines the image must be a gray color what am I doing wrong?

monotone = zeros (10,10) - 1;

monotone_gray = 0.8 * [1 1 1];

monotone_matrix (montone, 1:3) = [ montone_gray ];

axis off;

grid on;

image(unclicked)

Thank you

Answer 1

[Thorsten]

Th showing a gray matrix is easy:

I = 0.8*ones(10,10);
imshow(I)

But removing the axis but keeping the grid is not, because ticks and gridlines are linked.

But you can use line to draw your own lines.